In rodents,well characterized neurogenic niches of the adult brain,such as the subventricular zone of the lateral ventricles and the subgranular zone of the hippocampus,support the maintenance of neural/stem progenito...In rodents,well characterized neurogenic niches of the adult brain,such as the subventricular zone of the lateral ventricles and the subgranular zone of the hippocampus,support the maintenance of neural/stem progenitor cells(NSPCs)and the production of new neurons throughout the lifespan.The adult neurogenic process is dependent on the intrinsic gene expression signatures of NSPCs that make them competent for self-renewal and neuronal differentiation.At the same time,it is receptive to regulation by various extracellular signals that allow the modulation of neuronal production and integration into brain circuitries by various physiological stimuli.A drawback of this plasticity is the sensitivity of adult neurogenesis to alterations of the niche environment that can occur due to aging,injury or disease.At the core of the molecular mechanisms regulating neurogenesis,several transcription factors have been identified that maintain NSPC identity and mediate NSPC response to extrinsic cues.Here,we focus on REST,Egr1 and Dbx2 and their roles in adult neurogenesis,especially in the subventricular zone.We review recent work from our and other laboratories implicating these transcription factors in the control of NSPC proliferation and differentiation and in the response of NSPCs to extrinsic influences from the niche.We also discuss how their altered regulation may affect the neurogenic process in the aged and in the diseased brain.Finally,we highlight key open questions that need to be addressed to foster our understanding of the transcriptional mechanisms controlling adult neurogenesis.展开更多
Temperature influences the distribution, range, and phenology of plants. The key transcriptional activators of heat shock response in eukaryotes, the heat shock factors (HSFs), have undergone large-scale gene amplif...Temperature influences the distribution, range, and phenology of plants. The key transcriptional activators of heat shock response in eukaryotes, the heat shock factors (HSFs), have undergone large-scale gene amplification in plants. While HSFs are central in heat stress responses, their role in the response to ambient temperature changes is less well understood. We show here that the warm ambient temperature transcriptome is dependent upon the HSFA1 clade ofArabidopsis HSFs, which cause a rapid and dynamic eviction of H2A.Z nucleosomes at target genes. A transcriptional cascade results in the activation of multiple downstream stress-responsive transcription factors, triggering large-scale changes to the transcriptome in response to elevated temperature. H2A.Z nucleosomes are enriched at temperature-responsive genes at non-inducible temperature, and thus likely confer inducibility of gene expression and higher responsive dynamics. We propose that the antagonistic effects of H2A.Z and HSF1 provide a mechanism to activate gene expression rapidly and precisely in response to temperature, while preventing leaky transcription in the absence of an activation signal.展开更多
Transcription factor (TF) binding to its DNA target site plays an essential role in gene regulation. The location, orientation and spacing of transcription factor binding sites (TFBSs) also affect regulatory funct...Transcription factor (TF) binding to its DNA target site plays an essential role in gene regulation. The location, orientation and spacing of transcription factor binding sites (TFBSs) also affect regulatory function of the TF. However, how nucleosomal context of TFBSs influences TF binding and subsequent gene regulation remains to be elucidated. Using genome-wide nucleosome positioning and TF binding data in budding yeast, we found that binding affinities of TFs to DNA tend to decrease with increasing nucleosome occupancy of the associated binding sites. We further demonstrated that nucleosomal context of binding sites is correlated with gene regulation of the corresponding TF. Nucleosome-depleted TFBSs are linked to high gene activity and low expression noise, whereas nucleosome-covered TFBSs are associated with low gene activity and high expression noise. Moreover, nucleosome-covered TFBSs tend to disrupt coexpression of the corresponding TF target genes. We conclude that nucleosomal context of binding sites influences TF binding affinity, subsequently affecting the regulation of TFs on their target genes. This emphasizes the need to include nucleosomal context of TFBSs in modeling gene regulation.展开更多
The role of Ese-2,an Ets family transcription factor,in gene regulation is not known.In this study,the interactionbetween Ese-2 and cytokeratin 18(K18)intron 1 was characterized in lung epithelial cells.Reporter gene ...The role of Ese-2,an Ets family transcription factor,in gene regulation is not known.In this study,the interactionbetween Ese-2 and cytokeratin 18(K18)intron 1 was characterized in lung epithelial cells.Reporter gene assays showedEse-2 was able to upregulate K18 intron 1 enhanced reporter gene expression by approximately 2-fold.We found thatfull length Ese-2 did not bind DNA strongly,therefore truncated versions of the protein,containing the ETS domain orPointed domain,were created and tested in electrophoresis mobility shift assays.Multiple interactions between the ETSdomain and putative DNA binding sites within K18 intron 1 were observed,which led to the determination of a possibleEse-2 DNA binding consensus sequence.These experiments suggest that Ese-2 could play a role in the regulation ofK18 expression in lung epithelial cells.展开更多
Transcription factors (TFs) are key cellular components that control gene expression. They recognize specific DNA sequences, the TF binding sites (TFBSs), and thus are targeted to specific regions of the genome where ...Transcription factors (TFs) are key cellular components that control gene expression. They recognize specific DNA sequences, the TF binding sites (TFBSs), and thus are targeted to specific regions of the genome where they can recruit transcriptional co-factors and/or chromatin regulators to fine-tune spatiotemporal gene regulation. Therefore, the identification of TFBSs in genomic sequences and their subsequent quantitative modeling is of crucial importance for understanding and predicting gene expression. Here, we review how TFBSs can be determined experimentally, how the TFBS models can be constructed in silico, and how they can be optimized by taking into account features such as position interdependence within TFBSs, DNA shape, and/or by introducing state-of-the-art computational algorithms such as deep learning methods. In addition, we discuss the integration of context variables into the TFBS modeling, including nucleosome positioning, chromatin states, methylation patterns, 3D genome architectures, and TF cooperative binding, in order to better predict TF binding under cellular contexts. Finally, we explore the possibilities of combining the optimized TFBS model with technological advances, such as targeted TFBS perturbation by CRISPR, to better understand gene regulation, evolution, and plant diversity.展开更多
Cucurbitaceae is one of the most important plant families distributed worldwide.Transcription factors(TFs)regulate plant growth at the transcription level.Here,we performed a systematic analysis of 42641 TFs from 63 f...Cucurbitaceae is one of the most important plant families distributed worldwide.Transcription factors(TFs)regulate plant growth at the transcription level.Here,we performed a systematic analysis of 42641 TFs from 63 families in 14 Cucurbitaceae and 10 non-cucurbit species.Whole-genome duplication(WGD)was the dominant event type in almost all Cucurbitaceae plants.The TF families were divided into 1210 orthogroups(OGs),of which,112 were unique to Cucurbitaceae.Although the loss of several gene families was detected in Cucurbitaceae,the gene families expanded in five species that experienced a WGD event comparing with grape.Our findings revealed that the recent WGD events that had occurred in Cucurbitaceae played important roles in the expansion of most TF families.The functional enrichment analysis of the genes that significantly expanded or contracted uncovered five gene families,AUX/IAA,NAC,NBS,HB,and NF-YB.Finally,we conducted a comprehensive analysis of the TCP gene family and identified 16 tendril-related(TEN)genes in 11 Cucurbitaceae species.Interestingly,the characteristic sequence changed from CNNFYFP to CNNFYLP in the TEN gene(Bhi06M000087)of Benincasa hispida.Furthermore,we identified a new characteristic sequence,YNN,which could be used for TEN gene exploitation in Cucurbitaceae.In conclusion,this study will serve as a reference for studying the relationship between gene family evolution and genome duplication.Moreover,it will provide rich genetic resources for functional Cucurbitaceae studies in the future.展开更多
AIM: To observe the growth suppression effect of exogenous introduction of early growth response gene-1 (Egr-1 gene) on esophageal carcinoma tissue as well as on esophageal carcinoma cell line Eca109 and to explore th...AIM: To observe the growth suppression effect of exogenous introduction of early growth response gene-1 (Egr-1 gene) on esophageal carcinoma tissue as well as on esophageal carcinoma cell line Eca109 and to explore the potential application of Egr-1 gene in gene therapy of tumor. METHODS: Eukaryotic expression vector of PCMV-Egr-1 plasmid was introduced into Eca109 cell line which expressed no Egr-1 protein originally with lipofectamine transfection method. The introduction and expression of PCMV-Egr-1 plasmid into Eca109 cell line was confirmed by G418 selection culture, PCR amplification of neogene contained in the vector, Western blot analysis and immunocytochemical analysis. The cell growth curve, soft agar colony formation rate and tumorigenicity in SCID mice were examined to demonstrate the growth suppression effect of exogenous Egr-1 gene on Eca109 cell line. The Egr-1 mRNA and Egr-1 protein were also detected in 50 surgical specimens of esophageal carcinoma by in situ hybridization and immunohistochemistry. RESULTS: Exogenous Egr-1 gene was introduced successfully into Eca109 cell line and expressed Egr-1 protein stably. The transfected Eca109 cell line grew more slowly than control Eca109 as shown by cell growth curves, the soft agar colony formation rate (4.0% vs 6.9%, P 【 0.01) and the average growth rate of tumor in SCID mice (35.5 +/- 7.6 vs 65.8 +/- 7.6, P 【 0.05). The expression level of Egr-1 mRNA and protein significantly increased in dysplastic epithelia adjacent to cancer rather than in cancer tissues (65.8% vs 20.0% by ISH and 57.9% vs 0.01). CONCLUSION: Exogenous Egr-1 gene shows the strong effect of growth inhibition in Eca109 cell line. Egr-1 in the cancer tissue shows down-regulated expression that supports the inhibited function of Egr-1 in cancer growth and suggests Egr-1 may have an important role in gene therapy of esophageal carcinoma.展开更多
Identification of genetic signatures is the main objective for many computational oncology studies. The signature usually consists of numerous genes that are differentially expressed between two clinically distinct gr...Identification of genetic signatures is the main objective for many computational oncology studies. The signature usually consists of numerous genes that are differentially expressed between two clinically distinct groups of samples, such as tumor subtypes. Prospectively, many signatures have been found to generalize poorly to other datasets and, thus, have rarely been accepted into clinical use. Recognizing the limited success of traditionally generated signatures, we developed a systems biology-based framework for robust identification of key transcription factors and their genomic regulatory neighborhoods. Application of the framework to study the differences between gastrointestinal stromal tumor (GIST) and leiomyosarcoma (LMS) resulted in the identification of nine transcription factors (SRF, NKX2-5, CCDC6, LEF1, VDR, ZNF250, TRIM63, MAF, and MYC). Functional annotations of the obtained neighborhoods identified the biological processes which the key transcription factors regulate differently between the tumor types. Analyzing the differences in the expression patterns using our approach resulted in a more robust genetic signature and more biological insight into the diseases compared to a traditional genetic signature.展开更多
The HIV-1 LTR controls the expression of HIV-1 viral genes and thus is critical for viral propagation and pathology. Numerous host factors have been shown to participate in the regulation of the LTR promoter. Among th...The HIV-1 LTR controls the expression of HIV-1 viral genes and thus is critical for viral propagation and pathology. Numerous host factors have been shown to participate in the regulation of the LTR promoter. Among them is the thyroid hormone (T3) receptor (TR). TR has been shown to bind to the critical region of the promoter that contain the NFbB and Sp1 binding sites. Interestingly, earlier transient transfection studies in tissue culture cells have yielded contradicting conclusions on the role of TR in LTR regulation, likely due to the use of different cell types and/or lack of proper chromatin organization. Here, using the frog oocyte as a model system that allows replication-coupled chromatin assembly, mimicking that in somatic cells, we demonstrate that unliganded heterodimers of TR and RXR (9-cis retinoic acid receptor) repress LTR while the addition of T3 relieves the repression and further activates the promoter. More importantly, we show that chromatin and unliganded TR/RXR synergize to repress the promoter in a histone deacetylase-dependent manner.展开更多
Many marine invertebrate phyla are characterized by indirect development.These animals transit from planktonic larvae to benthic spats via settlement and metamorphosis,which contributes to their adaption to the marine...Many marine invertebrate phyla are characterized by indirect development.These animals transit from planktonic larvae to benthic spats via settlement and metamorphosis,which contributes to their adaption to the marine environment.Studying the biological process of metamorphosis is,thus,key to understanding the origin and evolution of indirect development.Although numerous studies have been conducted on the relationship between metamorphosis and the marine environment,microorganisms,and neurohormones,little is known about gene regulation network(GRN)dynamics during metamorphosis.Metamorphosis-competent pediveligers of the Pacific oyster Crassostrea gigas were assayed in this study.By assaying gene expression patterns and open chromatin region changes of different samples of larvae and spats,the dynamics of molecular regulation during metamorphosis were examined.The results indicated significantly different gene regulation networks before,during and post-metamorphosis.Genes encoding membrane-integrated receptors and those related to the remodeling of the nervous system were upregulated before the initiation of metamorphosis.Massive biogenesis,e.g.,of various enzymes and structural proteins,occurred during metamorphosis as inferred from the comprehensive upregulation of the protein synthesis system post epinephrine stimulation.Hierarchical downstream gene networks were then stimulated.Some transcription factors,including homeobox,basic helix–loop–helix and nuclear receptors,showed different temporal response patterns,suggesting a complex GRN during the transition stage.Nuclear receptors,as well as their retinoid X receptor partner,may participate in the GRN controlling oyster metamorphosis,indicating an ancient role of the nuclear receptor regulation system in animal metamorphosis.展开更多
Pioneer transcription factors(TFs)are a special category of TFs with the capacity to bind to closed chromatin regions in which DNA is wrapped around histones and may be highly methylated.Subsequently,pioneer TFs are a...Pioneer transcription factors(TFs)are a special category of TFs with the capacity to bind to closed chromatin regions in which DNA is wrapped around histones and may be highly methylated.Subsequently,pioneer TFs are able to modify the chromatin state to initiate gene expression.In plants,LEAFY(LFY)is a master floral regulator and has been suggested to act as a pioneer TF in Arabidopsis.Here,we demonstrate that LFY is able to bind both methylated and non-methylated DNA using a combination of in vitro genomewide binding experiments and structural modeling.Comparisons between regions bound by LFY in vivo and chromatin accessibility data suggest that a subset of LFY bound regions is occupied by nucleosomes.We confirm that LFY is able to bind nucleosomal DNA in vitro using reconstituted nucleosomes.Finally,we show that constitutive LFY expression in seedling tissues is sufficient to induce chromatin accessibility in the LFY direct target genes APETALA1 and AGAMOUS.Taken together,our study suggests that LFY possesses key pioneer TF features that contribute to launching the floral gene expression program.展开更多
Sesame(Sesamum indicum L.)is an ancient oilseed crop of the Pedaliaceae family with high oil content and potential health benefits.SHI RELATED SEQUENCE(SRS)proteins are the transcription factors(TFs)specific to plants...Sesame(Sesamum indicum L.)is an ancient oilseed crop of the Pedaliaceae family with high oil content and potential health benefits.SHI RELATED SEQUENCE(SRS)proteins are the transcription factors(TFs)specific to plants that contain RING-like zinc finger domain and are associated with the regulation of several physiological and biochemical processes.They also play vital roles in plant growth and development such as root formation,leaf development,floral development,hormone biosynthesis,signal transduction,and biotic and abiotic stress responses.Nevertheless,the SRS gene family was not reported in sesame yet.In this study,identification,molecular characterization,phylogenetic relationship,cis-acting regulatory elements,protein-protein interaction,syntenic relationship,duplication events and expression pattern of SRS genes were analyzed in S.indicum.We identified total six SiSRS genes on seven different linkage groups in the S.indicum genome by comparing with the other species,including the model plant Arabidopsis thaliana.The SiSRS genes showed variation in their structure like2–5 exons and 1–4 introns.Like other species,SiSRS proteins also contained‘RING-like zinc finger'and‘LRP1'domains.Then,the SiSRS genes were clustered into subclasses via phylogenetic analysis with proteins of S.indicum,A.thaliana,and some other plant species.The cis-acting regulatory elements analysis revealed that the promoter region of SiSRS4(SIN_1011561)showed the highest 13 and 16 elements for light-and phytohormone-responses whereas,SiSRS1(SIN_1015187)showed the highest 15 elements for stress-response.The ABREs,or ABA-responsive elements,were found in a maximum of 8 copies in the SiSRS3(SIN 1009100).Moreover,the available RNA-seq based expression of SiSRS genes revealed variation in expression patterns between stress-treated and non-treated samples,especially in drought and salinity conditions in.S.indicum.Two SiSRS genes like SiSRS1(SIN_1015187)and SiSRS5(SIN_1021065),also exhibited variable expression patterns between control vs PEG-treated sesame root samples and three SiSRS genes,including SiSRS1(SIN_1015187),SiSRS2(SIN_1003328)and SiSRS5(SIN_1021065)were responsive to salinity treatments.The present outcomes will encourage more research into the gene expression and functionality analysis of SiSRS genes in S.indicum and other related species.展开更多
Maintenance of homeostasis is pivotal to all forms of life. In the case of plants, homeostasis is constantly threatened by the inability to escape environmental fluctuations, and therefore sensitive mechanisms must ha...Maintenance of homeostasis is pivotal to all forms of life. In the case of plants, homeostasis is constantly threatened by the inability to escape environmental fluctuations, and therefore sensitive mechanisms must have evolved to allow rapid perception of environmental cues and concomitant modification of growth and developmental patterns for adaptation and survival. Re-establishment of homeostasis in response to environmental perturbations requires reprog- ramming of metabolism and gene expression to shunt energy sources from growth-related biosynthetic processes to defense, acclimation, and, ultimately, adaptation. Failure to mount an initial 'emergency' response may result in nutrient deprivation and irreversible senescence and cell death. Early signaling events largely determine the capacity of plants to orchestrate a successful adaptive response. Early events, on the other hand, are likely to be shared by different conditions through the generation of similar signals and before more specific responses are elaborated. Recent studies lend credence to this hypothesis, underpinning the importance of a shared energy signal in the transcriptional response to various types of stress. Energy deficiency is associated with most environmental perturbations due to their direct or indirect deleterious impact on photosynthesis and/or respiration. Several systems are known to have evolved for monitoring the available resources and triggering metabolic, growth, and developmental decisions accordingly. In doing so, energy-sensing systems regulate gene expression at multiple levels to allow flexibility in the diversity and the kinetics of the stress response.展开更多
Airway inflammation is the hallmark of many respiratory disorders, such as asthma and cystic fibrosis. Changes in airway gene expression triggered by inflammation play a key role in the pathogenesis of these diseases....Airway inflammation is the hallmark of many respiratory disorders, such as asthma and cystic fibrosis. Changes in airway gene expression triggered by inflammation play a key role in the pathogenesis of these diseases. Genetic linkage studies suggest that ESE-2 and ESE-3, which encode epithelium-specific Ets-domain-containing transcription factors, are candidate asthma susceptibility genes. We report here that the expression of another member of the Ets family transcription factors ESE-1, as well as ESE-3, is upregulated by the inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in bronchial epithelial cell lines. Treatment of these cells with IL-1β and TNF-α resulted in a dramatic increase in mRNA expression for both ESE-1 and ESE-3. We demonstrate that the induced expression is mediated by activation of the transcription factor NF-κB. We have characterized the ESE-1 and ESE-3 promoters and have identified the NF-κB binding sequences that are required for the cytokine-induced expression. In addition, we also demonstrate that ESE-1 upregulates ESE-3 expression and downregulates its own induction by cytokines. Finally, we have shown that in E/f3 (homologous to human ESE-1) knockout mice, the expression of the inflammatory cytokine interleukin-6 (IL-6) is downregulated. Our findings suggest that ESE-1 and ESE-3 play an important role in airway inflammation.展开更多
To explore the nature of eukaryotic transcription factor (TF) binding sites and determine how they differ from surrounding DNA sequences, we examined four features associated with DNA binding sites: G+C content, p...To explore the nature of eukaryotic transcription factor (TF) binding sites and determine how they differ from surrounding DNA sequences, we examined four features associated with DNA binding sites: G+C content, pattern complexity, palindromic structure, and Markov sequence ordering. Our analysis of the regulatory motifs obtained from the TRANSFAC databases using yeast intergenic sequences as background, revealed that these four features show variable enrichment in motif sequences. For example, motif sequences were more likely to have palindromic structure than were background sequences. In addition, these features were tightly localized to the regulatory motifs, indicating that they are a property of the motif sequences themselves and are not shared by the general promoter "environment" in which the regulatory motifs reside. By breaking down the motif sequences according to the TF classes to which they bind, more specific associations were identified. Finally, we found that some correlations, such as G+C content enrichment, were species-specific, while others, such as complexity enrichment, were universal across the species examined. The quantitative analysis provided here should increase our understanding of protein-DNA interactions and also help facilitate the discovery of regulatory motifs through bioinformatics.展开更多
Osteoarthritis (OA), the most common form of joint disease, is characterized clinically by joint pain, stiffness,and deformity. OA is now considered a whole joint disease;however, the breakdown of the articular cartil...Osteoarthritis (OA), the most common form of joint disease, is characterized clinically by joint pain, stiffness,and deformity. OA is now considered a whole joint disease;however, the breakdown of the articular cartilage remains themajor hallmark of the disease. Current treatments targeting OA symptoms have a limited impact on impeding orreversing the OA progression. Understanding the molecular and cellular mechanisms underlying OA development isa critical barrier to progress in OA therapy. Recent studies by the current authors’ group and others have revealedthat the nuclear factor of activated T cell 1 (NFAT1), a member of the NFAT family of transcription factors, regulatesthe expression of many anabolic and catabolic genes in articular chondrocytes of adult mice. Mice lacking NFAT1exhibit normal skeletal development but display OA in both appendicular and spinal facet joints as adults. Thisreview mainly focuses on the recent advances in the regulatory role of NFAT1 transcription factor in the activities ofarticular chondrocytes and its implication in the pathogenesis of OA.展开更多
Objective: To explore the mechanism of acupuncture for delaying aging. Methods: Using the senescence accelerated mouse pattern SAMP10 and the normal aging mice SAMR1 as models and applying RT-PCR and digoxin (DIG)-lab...Objective: To explore the mechanism of acupuncture for delaying aging. Methods: Using the senescence accelerated mouse pattern SAMP10 and the normal aging mice SAMR1 as models and applying RT-PCR and digoxin (DIG)-labeled Northern blot technique to observe expressions of NF-E2, YB-1, LRG47 genes in the forebrain, cortex and hippocampus in a 8-month old SAMR1 control group, a 8-month old SAMP10 control group, a 8-month old SAMP10 acupuncture group and a 8-month old SAMP10 non-point stimulation group. Results: In the SAMP10 control group, the expressions of NF-E2, YB-1 and LRG47 were down-regulated in the forebrain, cortex and hippocampus, and after acupuncture they were up-regulated and tended to normal. Conclusion: The brain aging of the SAMP10 mice is related with abnormal expressions of NF-E2, YB-1 and LRG47 genes; and acupuncture can regulate the expressions of NF-E2, YB-1 and LRG47 genes, strengthening the functions of erythrocyte series, increasing the proliferation of cells and enhancing the cellular immune function in anti-bacteria, hence delaying aging.展开更多
Iron is an essential element for life on Earth and its shortage, or excess, in the living organism may lead to severe health disorders. Plants serve as the primary source of dietary iron and improving crop iron conten...Iron is an essential element for life on Earth and its shortage, or excess, in the living organism may lead to severe health disorders. Plants serve as the primary source of dietary iron and improving crop iron content is an important step towards a better public health. Our review focuses on the control of iron acquisition in dicotyledonous plants and monocots that apply a reduction-based strategy in order to mobilize and import iron from the rhizosphere. Achieving a balance between shortage and excess of iron requires a tight regulation of the activity of the iron uptake system. A number of studies, ranging from single gene characterization to systems biology analyses, have led to the rapid expansion of our knowledge on iron uptake in recent years. Here, we summarize the novel insights into the regulation of iron ac- quisition and internal mobilization from intracellular stores. We present a detailed view of the main known regulatory networks defined by the Arabidopsis regulators FIT and POPEYE (PYE). Additionally, we analyze the root and leaf iron- responsive regulatory networks, revealing novel potential gene interactions and reliable iron-deficiency marker genes. We discuss perspectives and open questions with regard to iron sensing and post-translational regulation.展开更多
Xylanase 1 (Xyn1) is one of the two major representatives of the xylanase system of T. reesei; the mechanisms governing its expression were analysed throughout this study. All factors and regulatory motifs responsible...Xylanase 1 (Xyn1) is one of the two major representatives of the xylanase system of T. reesei; the mechanisms governing its expression were analysed throughout this study. All factors and regulatory motifs responsible for transcriptional regulation and the model of their interplay in induction and repression will be presented. Using in vivo foot printing analysis of xylan-induced and glucose repressed mycelia, we detected three adjacent nucleotide sequences contacted by DNA-binding proteins. Protection within the inverted repeat of the Cre1 (SYGGRG) consensus sequence on the non coding strand under repressing conditions is in perfect agreement with the previously reported Cre1 dependent glucose repression of xyn1. Constitutive protein binding could be observed to a CCAAT-box and an inverted repeat of a 5′ GGCTAA 3′ sequence. EMSA with crude extracts from induced and repressed mycelia revealed that the latter motifs are sufficient for formation of the basal transcriptional complex under all conditions. The inverted repeat of GGCTAA closely resembles the consensus sequences of the cellulase and xylanase regulators Ace1, Ace2 and, Xyr1 (encoded by xyr1, cloned and characterised in this study) EMSA with heterologously expressed components of each factor and of the T. reesei Hap2/3/5 protein complex revealed that the basal transcriptional complex is formed by Xyr1 and the Hap2/3/5. Additionally to the Cre1 mediated carbon catabolite repression a yet unknown mechanism antagonizing induction of xyn1 expression could be elucidated. Latter occurs through competition of the repressor Ace1 and Xyr1 for the GGCTAA motif. In vivo proof for the relevance of identified motifs could be given through analysis of T. reesei transformants containing correspondingly mutated versions of the xyn1 promoter fused to the A. niger goxA gene. The results indicated that the basal as well as the induction level of xyn1 gene transcription is dependent on an interaction of Xyr1 with the GGCTAA motif while formation of the CCAAT-Hap2/3/5 complex slightly reduces induction. It can be concluded that mutations impairing protein binding in vitro lead to a loss of distinct regulatory functions in xyn1 gene expression in vivo. A respective model of gene regulation will be presented.展开更多
To explore the biological characteristics of Vascular plant One-Zinc finger(VOZ)gene family in Populus trichocarpa,this paper used bioinformatics to analyze the nucleotide sequences and protein sequences of four membe...To explore the biological characteristics of Vascular plant One-Zinc finger(VOZ)gene family in Populus trichocarpa,this paper used bioinformatics to analyze the nucleotide sequences and protein sequences of four members of VOZ gene family of P.trichocarpa.The results showed that the four PtVOZ genes of P.trichocarpa were evenly distributed on four chromosomes.The length and molecular weight of the encoded protein were almost the same,and the subcellular localization was located in the nucleus,belonging to the unstable acidic hydrophilic non-aliphatic soluble protein.The gene structures were all in the patterns of 4 exons and 3 introns.The proportion order of PtVOZ transcription factor secondary structure components was random coil>αhelix>extended strand>βsheets,and the tertiary structure was very similar in spatial conformation.The phylogenetic tree analysis showed that P.trichocarpa was more closely related to VOZ transcription factors of dicotyledons.The four PtVOZ genes of P.trichocarpa were expressed in seedlings and different tissues,but there were differences in the expression intensity.This study provided a necessary theoretical basis for further exploring the molecular biological function of PtVOZ genes.展开更多
文摘In rodents,well characterized neurogenic niches of the adult brain,such as the subventricular zone of the lateral ventricles and the subgranular zone of the hippocampus,support the maintenance of neural/stem progenitor cells(NSPCs)and the production of new neurons throughout the lifespan.The adult neurogenic process is dependent on the intrinsic gene expression signatures of NSPCs that make them competent for self-renewal and neuronal differentiation.At the same time,it is receptive to regulation by various extracellular signals that allow the modulation of neuronal production and integration into brain circuitries by various physiological stimuli.A drawback of this plasticity is the sensitivity of adult neurogenesis to alterations of the niche environment that can occur due to aging,injury or disease.At the core of the molecular mechanisms regulating neurogenesis,several transcription factors have been identified that maintain NSPC identity and mediate NSPC response to extrinsic cues.Here,we focus on REST,Egr1 and Dbx2 and their roles in adult neurogenesis,especially in the subventricular zone.We review recent work from our and other laboratories implicating these transcription factors in the control of NSPC proliferation and differentiation and in the response of NSPCs to extrinsic influences from the niche.We also discuss how their altered regulation may affect the neurogenic process in the aged and in the diseased brain.Finally,we highlight key open questions that need to be addressed to foster our understanding of the transcriptional mechanisms controlling adult neurogenesis.
文摘Temperature influences the distribution, range, and phenology of plants. The key transcriptional activators of heat shock response in eukaryotes, the heat shock factors (HSFs), have undergone large-scale gene amplification in plants. While HSFs are central in heat stress responses, their role in the response to ambient temperature changes is less well understood. We show here that the warm ambient temperature transcriptome is dependent upon the HSFA1 clade ofArabidopsis HSFs, which cause a rapid and dynamic eviction of H2A.Z nucleosomes at target genes. A transcriptional cascade results in the activation of multiple downstream stress-responsive transcription factors, triggering large-scale changes to the transcriptome in response to elevated temperature. H2A.Z nucleosomes are enriched at temperature-responsive genes at non-inducible temperature, and thus likely confer inducibility of gene expression and higher responsive dynamics. We propose that the antagonistic effects of H2A.Z and HSF1 provide a mechanism to activate gene expression rapidly and precisely in response to temperature, while preventing leaky transcription in the absence of an activation signal.
基金supported by the Yat-Sen Innovative Talents Cultivation Program for Excellent Tutors
文摘Transcription factor (TF) binding to its DNA target site plays an essential role in gene regulation. The location, orientation and spacing of transcription factor binding sites (TFBSs) also affect regulatory function of the TF. However, how nucleosomal context of TFBSs influences TF binding and subsequent gene regulation remains to be elucidated. Using genome-wide nucleosome positioning and TF binding data in budding yeast, we found that binding affinities of TFs to DNA tend to decrease with increasing nucleosome occupancy of the associated binding sites. We further demonstrated that nucleosomal context of binding sites is correlated with gene regulation of the corresponding TF. Nucleosome-depleted TFBSs are linked to high gene activity and low expression noise, whereas nucleosome-covered TFBSs are associated with low gene activity and high expression noise. Moreover, nucleosome-covered TFBSs tend to disrupt coexpression of the corresponding TF target genes. We conclude that nucleosomal context of binding sites influences TF binding affinity, subsequently affecting the regulation of TFs on their target genes. This emphasizes the need to include nucleosomal context of TFBSs in modeling gene regulation.
基金This work was supported by operating grants from the Canadian Institutes of Health Researchthe Canadian Cystic Fibrosis Foundation(to J.H.)the Foundation Fighting Blindness—Canada(to J.H.).
文摘The role of Ese-2,an Ets family transcription factor,in gene regulation is not known.In this study,the interactionbetween Ese-2 and cytokeratin 18(K18)intron 1 was characterized in lung epithelial cells.Reporter gene assays showedEse-2 was able to upregulate K18 intron 1 enhanced reporter gene expression by approximately 2-fold.We found thatfull length Ese-2 did not bind DNA strongly,therefore truncated versions of the protein,containing the ETS domain orPointed domain,were created and tested in electrophoresis mobility shift assays.Multiple interactions between the ETSdomain and putative DNA binding sites within K18 intron 1 were observed,which led to the determination of a possibleEse-2 DNA binding consensus sequence.These experiments suggest that Ese-2 could play a role in the regulation ofK18 expression in lung epithelial cells.
文摘Transcription factors (TFs) are key cellular components that control gene expression. They recognize specific DNA sequences, the TF binding sites (TFBSs), and thus are targeted to specific regions of the genome where they can recruit transcriptional co-factors and/or chromatin regulators to fine-tune spatiotemporal gene regulation. Therefore, the identification of TFBSs in genomic sequences and their subsequent quantitative modeling is of crucial importance for understanding and predicting gene expression. Here, we review how TFBSs can be determined experimentally, how the TFBS models can be constructed in silico, and how they can be optimized by taking into account features such as position interdependence within TFBSs, DNA shape, and/or by introducing state-of-the-art computational algorithms such as deep learning methods. In addition, we discuss the integration of context variables into the TFBS modeling, including nucleosome positioning, chromatin states, methylation patterns, 3D genome architectures, and TF cooperative binding, in order to better predict TF binding under cellular contexts. Finally, we explore the possibilities of combining the optimized TFBS model with technological advances, such as targeted TFBS perturbation by CRISPR, to better understand gene regulation, evolution, and plant diversity.
基金supported by the Natural Science Foundation of Hebei(Grant No.C2021209005)National Natural Science Foundation of China(Grant No.32172583)+1 种基金the Natural Science Foundation for Distinguished Young Scholar of Hebei Province(Grant No.C2022209010)the China Postdoctoral Science Foundation(Grant Nos.2020M673188,2021T140097).
文摘Cucurbitaceae is one of the most important plant families distributed worldwide.Transcription factors(TFs)regulate plant growth at the transcription level.Here,we performed a systematic analysis of 42641 TFs from 63 families in 14 Cucurbitaceae and 10 non-cucurbit species.Whole-genome duplication(WGD)was the dominant event type in almost all Cucurbitaceae plants.The TF families were divided into 1210 orthogroups(OGs),of which,112 were unique to Cucurbitaceae.Although the loss of several gene families was detected in Cucurbitaceae,the gene families expanded in five species that experienced a WGD event comparing with grape.Our findings revealed that the recent WGD events that had occurred in Cucurbitaceae played important roles in the expansion of most TF families.The functional enrichment analysis of the genes that significantly expanded or contracted uncovered five gene families,AUX/IAA,NAC,NBS,HB,and NF-YB.Finally,we conducted a comprehensive analysis of the TCP gene family and identified 16 tendril-related(TEN)genes in 11 Cucurbitaceae species.Interestingly,the characteristic sequence changed from CNNFYFP to CNNFYLP in the TEN gene(Bhi06M000087)of Benincasa hispida.Furthermore,we identified a new characteristic sequence,YNN,which could be used for TEN gene exploitation in Cucurbitaceae.In conclusion,this study will serve as a reference for studying the relationship between gene family evolution and genome duplication.Moreover,it will provide rich genetic resources for functional Cucurbitaceae studies in the future.
基金Supported by the National Natural Science Foundation of China,No.39670298.
文摘AIM: To observe the growth suppression effect of exogenous introduction of early growth response gene-1 (Egr-1 gene) on esophageal carcinoma tissue as well as on esophageal carcinoma cell line Eca109 and to explore the potential application of Egr-1 gene in gene therapy of tumor. METHODS: Eukaryotic expression vector of PCMV-Egr-1 plasmid was introduced into Eca109 cell line which expressed no Egr-1 protein originally with lipofectamine transfection method. The introduction and expression of PCMV-Egr-1 plasmid into Eca109 cell line was confirmed by G418 selection culture, PCR amplification of neogene contained in the vector, Western blot analysis and immunocytochemical analysis. The cell growth curve, soft agar colony formation rate and tumorigenicity in SCID mice were examined to demonstrate the growth suppression effect of exogenous Egr-1 gene on Eca109 cell line. The Egr-1 mRNA and Egr-1 protein were also detected in 50 surgical specimens of esophageal carcinoma by in situ hybridization and immunohistochemistry. RESULTS: Exogenous Egr-1 gene was introduced successfully into Eca109 cell line and expressed Egr-1 protein stably. The transfected Eca109 cell line grew more slowly than control Eca109 as shown by cell growth curves, the soft agar colony formation rate (4.0% vs 6.9%, P 【 0.01) and the average growth rate of tumor in SCID mice (35.5 +/- 7.6 vs 65.8 +/- 7.6, P 【 0.05). The expression level of Egr-1 mRNA and protein significantly increased in dysplastic epithelia adjacent to cancer rather than in cancer tissues (65.8% vs 20.0% by ISH and 57.9% vs 0.01). CONCLUSION: Exogenous Egr-1 gene shows the strong effect of growth inhibition in Eca109 cell line. Egr-1 in the cancer tissue shows down-regulated expression that supports the inhibited function of Egr-1 in cancer growth and suggests Egr-1 may have an important role in gene therapy of esophageal carcinoma.
基金supported by Project for the Biological Information and Information Processing Properties of Biological Systems from the Academy of Finland(No.122973)Project for the Structure-dynamics Relationships in Biological Network from the Academy of Finland(No.132877)Finnish Funding Agency for Technology and Innovation Finland Distinguished Professor program(No.1480/31/09)
文摘Identification of genetic signatures is the main objective for many computational oncology studies. The signature usually consists of numerous genes that are differentially expressed between two clinically distinct groups of samples, such as tumor subtypes. Prospectively, many signatures have been found to generalize poorly to other datasets and, thus, have rarely been accepted into clinical use. Recognizing the limited success of traditionally generated signatures, we developed a systems biology-based framework for robust identification of key transcription factors and their genomic regulatory neighborhoods. Application of the framework to study the differences between gastrointestinal stromal tumor (GIST) and leiomyosarcoma (LMS) resulted in the identification of nine transcription factors (SRF, NKX2-5, CCDC6, LEF1, VDR, ZNF250, TRIM63, MAF, and MYC). Functional annotations of the obtained neighborhoods identified the biological processes which the key transcription factors regulate differently between the tumor types. Analyzing the differences in the expression patterns using our approach resulted in a more robust genetic signature and more biological insight into the diseases compared to a traditional genetic signature.
文摘The HIV-1 LTR controls the expression of HIV-1 viral genes and thus is critical for viral propagation and pathology. Numerous host factors have been shown to participate in the regulation of the LTR promoter. Among them is the thyroid hormone (T3) receptor (TR). TR has been shown to bind to the critical region of the promoter that contain the NFbB and Sp1 binding sites. Interestingly, earlier transient transfection studies in tissue culture cells have yielded contradicting conclusions on the role of TR in LTR regulation, likely due to the use of different cell types and/or lack of proper chromatin organization. Here, using the frog oocyte as a model system that allows replication-coupled chromatin assembly, mimicking that in somatic cells, we demonstrate that unliganded heterodimers of TR and RXR (9-cis retinoic acid receptor) repress LTR while the addition of T3 relieves the repression and further activates the promoter. More importantly, we show that chromatin and unliganded TR/RXR synergize to repress the promoter in a histone deacetylase-dependent manner.
基金supported by the Oceanographic Data Center,IOCAS.We acknowledge financial support from the Science&Technology Innovation Project of Laoshan Laboratory(LSKJ202203001)the Key Research and Development Program of Shandong(2022LZGC015),and the Taishan Scholars Program.
文摘Many marine invertebrate phyla are characterized by indirect development.These animals transit from planktonic larvae to benthic spats via settlement and metamorphosis,which contributes to their adaption to the marine environment.Studying the biological process of metamorphosis is,thus,key to understanding the origin and evolution of indirect development.Although numerous studies have been conducted on the relationship between metamorphosis and the marine environment,microorganisms,and neurohormones,little is known about gene regulation network(GRN)dynamics during metamorphosis.Metamorphosis-competent pediveligers of the Pacific oyster Crassostrea gigas were assayed in this study.By assaying gene expression patterns and open chromatin region changes of different samples of larvae and spats,the dynamics of molecular regulation during metamorphosis were examined.The results indicated significantly different gene regulation networks before,during and post-metamorphosis.Genes encoding membrane-integrated receptors and those related to the remodeling of the nervous system were upregulated before the initiation of metamorphosis.Massive biogenesis,e.g.,of various enzymes and structural proteins,occurred during metamorphosis as inferred from the comprehensive upregulation of the protein synthesis system post epinephrine stimulation.Hierarchical downstream gene networks were then stimulated.Some transcription factors,including homeobox,basic helix–loop–helix and nuclear receptors,showed different temporal response patterns,suggesting a complex GRN during the transition stage.Nuclear receptors,as well as their retinoid X receptor partner,may participate in the GRN controlling oyster metamorphosis,indicating an ancient role of the nuclear receptor regulation system in animal metamorphosis.
基金supported by the ANR-DFG project Flopinet(ANR-16-CE92-0023-01)to C.Z.and F.P.,and GRALa program from the Chemistry Biology Health(CBH)Graduate School of University Grenoble Alpes(ANR-17-EURE-0003)to C.Z.,F.P.,and A.S.
文摘Pioneer transcription factors(TFs)are a special category of TFs with the capacity to bind to closed chromatin regions in which DNA is wrapped around histones and may be highly methylated.Subsequently,pioneer TFs are able to modify the chromatin state to initiate gene expression.In plants,LEAFY(LFY)is a master floral regulator and has been suggested to act as a pioneer TF in Arabidopsis.Here,we demonstrate that LFY is able to bind both methylated and non-methylated DNA using a combination of in vitro genomewide binding experiments and structural modeling.Comparisons between regions bound by LFY in vivo and chromatin accessibility data suggest that a subset of LFY bound regions is occupied by nucleosomes.We confirm that LFY is able to bind nucleosomal DNA in vitro using reconstituted nucleosomes.Finally,we show that constitutive LFY expression in seedling tissues is sufficient to induce chromatin accessibility in the LFY direct target genes APETALA1 and AGAMOUS.Taken together,our study suggests that LFY possesses key pioneer TF features that contribute to launching the floral gene expression program.
文摘Sesame(Sesamum indicum L.)is an ancient oilseed crop of the Pedaliaceae family with high oil content and potential health benefits.SHI RELATED SEQUENCE(SRS)proteins are the transcription factors(TFs)specific to plants that contain RING-like zinc finger domain and are associated with the regulation of several physiological and biochemical processes.They also play vital roles in plant growth and development such as root formation,leaf development,floral development,hormone biosynthesis,signal transduction,and biotic and abiotic stress responses.Nevertheless,the SRS gene family was not reported in sesame yet.In this study,identification,molecular characterization,phylogenetic relationship,cis-acting regulatory elements,protein-protein interaction,syntenic relationship,duplication events and expression pattern of SRS genes were analyzed in S.indicum.We identified total six SiSRS genes on seven different linkage groups in the S.indicum genome by comparing with the other species,including the model plant Arabidopsis thaliana.The SiSRS genes showed variation in their structure like2–5 exons and 1–4 introns.Like other species,SiSRS proteins also contained‘RING-like zinc finger'and‘LRP1'domains.Then,the SiSRS genes were clustered into subclasses via phylogenetic analysis with proteins of S.indicum,A.thaliana,and some other plant species.The cis-acting regulatory elements analysis revealed that the promoter region of SiSRS4(SIN_1011561)showed the highest 13 and 16 elements for light-and phytohormone-responses whereas,SiSRS1(SIN_1015187)showed the highest 15 elements for stress-response.The ABREs,or ABA-responsive elements,were found in a maximum of 8 copies in the SiSRS3(SIN 1009100).Moreover,the available RNA-seq based expression of SiSRS genes revealed variation in expression patterns between stress-treated and non-treated samples,especially in drought and salinity conditions in.S.indicum.Two SiSRS genes like SiSRS1(SIN_1015187)and SiSRS5(SIN_1021065),also exhibited variable expression patterns between control vs PEG-treated sesame root samples and three SiSRS genes,including SiSRS1(SIN_1015187),SiSRS2(SIN_1003328)and SiSRS5(SIN_1021065)were responsive to salinity treatments.The present outcomes will encourage more research into the gene expression and functionality analysis of SiSRS genes in S.indicum and other related species.
文摘Maintenance of homeostasis is pivotal to all forms of life. In the case of plants, homeostasis is constantly threatened by the inability to escape environmental fluctuations, and therefore sensitive mechanisms must have evolved to allow rapid perception of environmental cues and concomitant modification of growth and developmental patterns for adaptation and survival. Re-establishment of homeostasis in response to environmental perturbations requires reprog- ramming of metabolism and gene expression to shunt energy sources from growth-related biosynthetic processes to defense, acclimation, and, ultimately, adaptation. Failure to mount an initial 'emergency' response may result in nutrient deprivation and irreversible senescence and cell death. Early signaling events largely determine the capacity of plants to orchestrate a successful adaptive response. Early events, on the other hand, are likely to be shared by different conditions through the generation of similar signals and before more specific responses are elaborated. Recent studies lend credence to this hypothesis, underpinning the importance of a shared energy signal in the transcriptional response to various types of stress. Energy deficiency is associated with most environmental perturbations due to their direct or indirect deleterious impact on photosynthesis and/or respiration. Several systems are known to have evolved for monitoring the available resources and triggering metabolic, growth, and developmental decisions accordingly. In doing so, energy-sensing systems regulate gene expression at multiple levels to allow flexibility in the diversity and the kinetics of the stress response.
文摘Airway inflammation is the hallmark of many respiratory disorders, such as asthma and cystic fibrosis. Changes in airway gene expression triggered by inflammation play a key role in the pathogenesis of these diseases. Genetic linkage studies suggest that ESE-2 and ESE-3, which encode epithelium-specific Ets-domain-containing transcription factors, are candidate asthma susceptibility genes. We report here that the expression of another member of the Ets family transcription factors ESE-1, as well as ESE-3, is upregulated by the inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in bronchial epithelial cell lines. Treatment of these cells with IL-1β and TNF-α resulted in a dramatic increase in mRNA expression for both ESE-1 and ESE-3. We demonstrate that the induced expression is mediated by activation of the transcription factor NF-κB. We have characterized the ESE-1 and ESE-3 promoters and have identified the NF-κB binding sequences that are required for the cytokine-induced expression. In addition, we also demonstrate that ESE-1 upregulates ESE-3 expression and downregulates its own induction by cytokines. Finally, we have shown that in E/f3 (homologous to human ESE-1) knockout mice, the expression of the inflammatory cytokine interleukin-6 (IL-6) is downregulated. Our findings suggest that ESE-1 and ESE-3 play an important role in airway inflammation.
文摘To explore the nature of eukaryotic transcription factor (TF) binding sites and determine how they differ from surrounding DNA sequences, we examined four features associated with DNA binding sites: G+C content, pattern complexity, palindromic structure, and Markov sequence ordering. Our analysis of the regulatory motifs obtained from the TRANSFAC databases using yeast intergenic sequences as background, revealed that these four features show variable enrichment in motif sequences. For example, motif sequences were more likely to have palindromic structure than were background sequences. In addition, these features were tightly localized to the regulatory motifs, indicating that they are a property of the motif sequences themselves and are not shared by the general promoter "environment" in which the regulatory motifs reside. By breaking down the motif sequences according to the TF classes to which they bind, more specific associations were identified. Finally, we found that some correlations, such as G+C content enrichment, were species-specific, while others, such as complexity enrichment, were universal across the species examined. The quantitative analysis provided here should increase our understanding of protein-DNA interactions and also help facilitate the discovery of regulatory motifs through bioinformatics.
基金supported by the United States National Institutes of Health(NIH)under Award Number R01 AR059088(to J.W.)the Mary A.and Paul R.Harrington Distinguished Professorship Endowment.
文摘Osteoarthritis (OA), the most common form of joint disease, is characterized clinically by joint pain, stiffness,and deformity. OA is now considered a whole joint disease;however, the breakdown of the articular cartilage remains themajor hallmark of the disease. Current treatments targeting OA symptoms have a limited impact on impeding orreversing the OA progression. Understanding the molecular and cellular mechanisms underlying OA development isa critical barrier to progress in OA therapy. Recent studies by the current authors’ group and others have revealedthat the nuclear factor of activated T cell 1 (NFAT1), a member of the NFAT family of transcription factors, regulatesthe expression of many anabolic and catabolic genes in articular chondrocytes of adult mice. Mice lacking NFAT1exhibit normal skeletal development but display OA in both appendicular and spinal facet joints as adults. Thisreview mainly focuses on the recent advances in the regulatory role of NFAT1 transcription factor in the activities ofarticular chondrocytes and its implication in the pathogenesis of OA.
文摘Objective: To explore the mechanism of acupuncture for delaying aging. Methods: Using the senescence accelerated mouse pattern SAMP10 and the normal aging mice SAMR1 as models and applying RT-PCR and digoxin (DIG)-labeled Northern blot technique to observe expressions of NF-E2, YB-1, LRG47 genes in the forebrain, cortex and hippocampus in a 8-month old SAMR1 control group, a 8-month old SAMP10 control group, a 8-month old SAMP10 acupuncture group and a 8-month old SAMP10 non-point stimulation group. Results: In the SAMP10 control group, the expressions of NF-E2, YB-1 and LRG47 were down-regulated in the forebrain, cortex and hippocampus, and after acupuncture they were up-regulated and tended to normal. Conclusion: The brain aging of the SAMP10 mice is related with abnormal expressions of NF-E2, YB-1 and LRG47 genes; and acupuncture can regulate the expressions of NF-E2, YB-1 and LRG47 genes, strengthening the functions of erythrocyte series, increasing the proliferation of cells and enhancing the cellular immune function in anti-bacteria, hence delaying aging.
文摘Iron is an essential element for life on Earth and its shortage, or excess, in the living organism may lead to severe health disorders. Plants serve as the primary source of dietary iron and improving crop iron content is an important step towards a better public health. Our review focuses on the control of iron acquisition in dicotyledonous plants and monocots that apply a reduction-based strategy in order to mobilize and import iron from the rhizosphere. Achieving a balance between shortage and excess of iron requires a tight regulation of the activity of the iron uptake system. A number of studies, ranging from single gene characterization to systems biology analyses, have led to the rapid expansion of our knowledge on iron uptake in recent years. Here, we summarize the novel insights into the regulation of iron ac- quisition and internal mobilization from intracellular stores. We present a detailed view of the main known regulatory networks defined by the Arabidopsis regulators FIT and POPEYE (PYE). Additionally, we analyze the root and leaf iron- responsive regulatory networks, revealing novel potential gene interactions and reliable iron-deficiency marker genes. We discuss perspectives and open questions with regard to iron sensing and post-translational regulation.
文摘Xylanase 1 (Xyn1) is one of the two major representatives of the xylanase system of T. reesei; the mechanisms governing its expression were analysed throughout this study. All factors and regulatory motifs responsible for transcriptional regulation and the model of their interplay in induction and repression will be presented. Using in vivo foot printing analysis of xylan-induced and glucose repressed mycelia, we detected three adjacent nucleotide sequences contacted by DNA-binding proteins. Protection within the inverted repeat of the Cre1 (SYGGRG) consensus sequence on the non coding strand under repressing conditions is in perfect agreement with the previously reported Cre1 dependent glucose repression of xyn1. Constitutive protein binding could be observed to a CCAAT-box and an inverted repeat of a 5′ GGCTAA 3′ sequence. EMSA with crude extracts from induced and repressed mycelia revealed that the latter motifs are sufficient for formation of the basal transcriptional complex under all conditions. The inverted repeat of GGCTAA closely resembles the consensus sequences of the cellulase and xylanase regulators Ace1, Ace2 and, Xyr1 (encoded by xyr1, cloned and characterised in this study) EMSA with heterologously expressed components of each factor and of the T. reesei Hap2/3/5 protein complex revealed that the basal transcriptional complex is formed by Xyr1 and the Hap2/3/5. Additionally to the Cre1 mediated carbon catabolite repression a yet unknown mechanism antagonizing induction of xyn1 expression could be elucidated. Latter occurs through competition of the repressor Ace1 and Xyr1 for the GGCTAA motif. In vivo proof for the relevance of identified motifs could be given through analysis of T. reesei transformants containing correspondingly mutated versions of the xyn1 promoter fused to the A. niger goxA gene. The results indicated that the basal as well as the induction level of xyn1 gene transcription is dependent on an interaction of Xyr1 with the GGCTAA motif while formation of the CCAAT-Hap2/3/5 complex slightly reduces induction. It can be concluded that mutations impairing protein binding in vitro lead to a loss of distinct regulatory functions in xyn1 gene expression in vivo. A respective model of gene regulation will be presented.
文摘To explore the biological characteristics of Vascular plant One-Zinc finger(VOZ)gene family in Populus trichocarpa,this paper used bioinformatics to analyze the nucleotide sequences and protein sequences of four members of VOZ gene family of P.trichocarpa.The results showed that the four PtVOZ genes of P.trichocarpa were evenly distributed on four chromosomes.The length and molecular weight of the encoded protein were almost the same,and the subcellular localization was located in the nucleus,belonging to the unstable acidic hydrophilic non-aliphatic soluble protein.The gene structures were all in the patterns of 4 exons and 3 introns.The proportion order of PtVOZ transcription factor secondary structure components was random coil>αhelix>extended strand>βsheets,and the tertiary structure was very similar in spatial conformation.The phylogenetic tree analysis showed that P.trichocarpa was more closely related to VOZ transcription factors of dicotyledons.The four PtVOZ genes of P.trichocarpa were expressed in seedlings and different tissues,but there were differences in the expression intensity.This study provided a necessary theoretical basis for further exploring the molecular biological function of PtVOZ genes.