Translational regulation of DNA repair systems by eIF3a in cancer chemotherapeutic response

OBJECTIVE To investigate the role of e IF3a in the regulation of DNA repair pathways in cancer chemotherapeutic response.METHODS Immunohistochemistry was used to determine the expression of e IF3a in lung and breast cancer tissues followed by association analysis of e IF3a expression with patient′s response to chemotherapy.Ectopic overexpression and RNA interference knockdown of e IF3a were carried out in NIH3T3and H1299 cell lines,respectively,to determine the effect of altered e IF3a expression on cellular response to chemotherapeutic drugs by using MTT assay.The DNA repair capacity of these cells was evaluated by using host-cell reactivation,NHEJ and HR assay.Real-time reverse transcriptase PCR and Western Blot analyses were carried out to determine the effect of e IF3a on the DNA repair genes by using cells with altered e IF3a expression.RESULTS e IF3a expression associates with response of lung and breast cancer patients to platinum and anthracycline.e IF3a knockdown or overexpression,respectively,increased and decreased the cellular resistance to cisplatin and anthracycline anticancer drugs,DNA repair activity,and expression of NER and NHEJ DNA repair proteins.CONCLUSION e IF3a plays an important role in regulating the expression of NER and NHEJ DNA repair proteins which,in turn,contributes to cellular response to DNA-damaging anticancer drugs and patients′response to platinum and anthracycline chemotherapy.

mRNA-specific translational regulation in yeast

The expression of a gene is governed at various levels,from transcriptional to translational level.The translational control is widely used to regulate gene expression,especially when a rapid,local,and selective control over protein synthesis is required.The present review describes instructive examples of translational regulation in yeast,together with regulatory elements within mRNAs.The review also outlines the important contributions of mRNA-binding proteins that act in harmony with several translational elements to generate appropriate translational signals and responses.

Polyglutamylase activity of tubulin tyrosine ligase-like 4 is negatively regulated by the never in mitosis gene A family kinase never in mitosis gene A-related kinase 5

BACKGROUND Tubulins,building blocks of microtubules,are modified substrates of diverse post-translational modifications including phosphorylation,polyglycylation and polyglutamylation.Polyglutamylation of microtubules,catalyzed by enzymes from the tubulin tyrosine ligase-like(TTLL)family,can regulate interactions with molecular motors and other proteins.Due to the diversity and functional importance of microtubule modifications,strict control of the TTLL enzymes has been suggested.AIM To characterize the interaction between never in mitosis gene A-related kinase 5(NEK5)and TTLL4 proteins and the effects of TTLL4 phosphorylation.METHODS The interaction between NEK5 and TTLL4 was identified by yeast two-hybrid screening using the C-terminus of NEK5(a.a.260–708)as bait and confirmed by immunoprecipitation.The phosphorylation sites of TTLL4 were identified by mass spectrometry and point mutations were introduced.RESULTS Here,we show that NEK5 interacts with TTLL4 and regulates its polyglutamylation activity.We further show that NEK5 can also interact with TTLL5 and TTLL7.The silencing of NEK5 increases the levels of polyglutamylation of proteins by increasing the activity of TTLL4.The same effects were observed after the expression of the catalytically inactive form of NEK5.This regulation of TTLL4 activity involves its phosphorylation at Y815 and S1136 amino acid residues.CONCLUSION Our results demonstrate,for the first time,the regulation of TTLL activity through phosphorylation,pointing to NEK5 as a potential effector kinase.We also suggest a general control of tubulin polyglutamylation through NEK family members in human cells.

From Farming to Engineering： The Microbiota and Allergic Diseases

The steady increase of lgE-dependent allergic diseases after the Second World War is a unique phenomenon in the history of humankind. Numerous cross-sectional studies, comprehensive longitudinal cohort studies of children living in various types of environment, and mechanistic experimental studies have pointed to the disappearance of ＂protective factors＂ related to major changes in lifestyle and environment. A common unifying concept is that of the immunoregulatory role of the gut microbiota. This review focuses on the protection against allergic disorders that is provided by the farming environment and by exposure to microbial diversity. It also questions whether and how microbial bioengineering will be able in the future to restore an interplay that was beneficial to the proper immunological development of children in the past and that was irreversibly disrupted by changes in lifestyle. The protective ＂farming environment＂ includes independent and additional influences： contact with animals, stay in barns/stables, and consumption of unprocessed milk and milk products, by mothers during pregnancy and by children in early life. More than the overall quanti- ty of microbes, the biodiversity of the farm microbial environment appears to be crucial for this protection, as does the biodiversity of the gut microbiota that it may provide. Use of conventional probiotics, especially various species or strains of Lactobacillus and Bifidobacterium, has not fulfilled the expectations of allergists and pediatricians to prevent allergy. Among the specific organisms present in cowsheds that could be used for prevention, Acinetobacter （A.） lwoffii F78, Lactococcus （ L.） lactis G121, and Staphylococcus （S.） sciuri W620 seem to be the most promising, based on experimental studies in mouse models of allergic respiratory diseases. However, the development of a new generation of probiotics based on very productive research on the farming environment faces several obstacles that cannot be overcome without a close collaboration between microbiologists, immunologists, and bioengineers, as well as pediatricians, allergists, specialists of clinical trials, and ethical committees.

Plant target of rapamycin signaling network:Complexes,conservations,and specificities

Target of rapamycin(TOR)is an evolutionarily conserved protein kinase that functions as a central signaling hub to integrate diverse internal and external cues to precisely orchestrate cellular and organismal physiology.During evolution,TOR both maintains the highly conserved TOR complex compositions,and cellular and molecular functions,but also evolves distinctive roles and strategies to modulate cell growth,proliferation,metabolism,survival,and stress responses in eukaryotes.Here,we review recent discoveries on the plant TOR signaling network.We present an overview of plant TOR complexes,analyze the signaling landscape of the plant TOR signaling network from the upstream signals that regulate plant TOR activation to the downstream effectors involved in various biological processes,and compare their conservation and specificities within different biological contexts.Finally,we summarize the impact of dysregulation of TOR signaling on every stage of plant growth and development,from embryogenesis and seedling growth,to flowering and senescence.

Ribosome Profiling Reveals Genome-wide Cellular Translational Regulation upon Heat Stress in Escherichia coli

Heat shock response is a classical stress-induced regulatory system in bacteria, character- ized by extensive transcriptional reprogramming. To compare the impact of heat stress on the tran- scriptome and translatome in Escherich＆ coli, we conducted ribosome profiling in parallel with RNA-Seq to investigate the alterations in transcription and translation efficiency when E. coli cells were exposed to a mild heat stress （from 30 ~C to 45 ~C）. While general changes in ribosome foot- prints correlate with the changes of mRNA transcripts upon heat stress, a number of genes show differential changes at the transcription and translation levels. Translation efficiency of a few genes that are related to environment stimulus response is up-regulated, and in contrast, some genes func- tioning in mRNA translation and amino acid biosynthesis are down-regulated at the translation level in response to heat stress. Moreover, our ribosome occupancy data suggest that in generalribosomes accumulate remarkably in the starting regions of ORFs upon heat stress. This study pro- vides additional insights into bacterial gene expression in response to heat stress, and suggests the presence of stress-induced but yet-to-be characterized cellular regulatory mechanisms of gene expression at translation level.

SUMO E3 Ligases GmSIZ1a and GmSIZ1b regulate vegetative growth in soybean

SIZ1 is a small ubiquitin-related modifier（SUMO） E3 ligase that mediates post-translational SUMO modification of target proteins and thereby regulates developmental processes and hormonal and environmental stress responses in Arabidopsis. However,the role of SUMO E3 ligases in crop plants is largely unknown. Here, we identified and characterized two Glycine max（soybean） SUMO E3 ligases, GmSIZ1a and GmSIZ1b. Expression of GmSIZ1a and GmSIZ1b was induced in response to salicylic acid（SA）, heat, and dehydration treatment, but not in response to cold, abscisic acid（ABA）, and Na Cl treatment. Although GmSIZ1a was expressed at higher levels than GmSIZ1b, both genes encoded proteins with SUMO E3 ligase activity in vivo.Heterologous expression of GmSIZ1a or GmSIZ1b rescued the mutant phenotype of Arabidopsis siz1-2, including dwarfism, constitutively activated expression of pathogen-related genes, and ABA-sensitive seed germination.Simultaneous downregulation of GmSIZ1a and GmSIZ1b（GmSIZ1a/b） using RNA interference（RNAi）-mediated gene silencing decreased heat shock-induced SUMO conjugation in soybean. Moreover, GmSIZ1 RNAi plants exhibited reduced plant height and leaf size. However,unlike Arabidopsis siz1-2 mutant plants, flowering time and SA levels were not significantly altered in GmSIZ1 RNAi plants. Taken together, our results indicate that GmSIZ1a and GmSIZ1b mediate SUMO modification and positively regulate vegetative growth in soybean.

Combined analyses of translatome and transcriptome in Arabidopsis reveal new players responding to magnesium deficiency

Translational control of gene expression,including recruitment of ribosomes to messenger RNA(mRNA),is particularly important during the response to stress.Purification of ribosomeassociated mRNAs using translating ribosome affinity purification(TRAP)followed by RNAsequencing facilitates the study of mRNAs undergoing active transcription and better proxies the translatome,or protein response,to stimuli.To identify plant responses to Magnesium(Mg)deficiency at the translational level,we combined transcriptome and translatome analyses.Excitingly,we found 26 previously unreported Mg-responsive genes that were only regulated at the translational level and not the transcriptional level,during the early response to Mg deficiency.In addition,mutants of the transcription factor ELONGATED HYPOCOTYL 5(HY5),the H^(+)/CATION EXCHANGER 1 and 3(CAX1 and CAX3),and UBIQUITIN 11(UBQ11)exhibited early chlorosis phenotype under Mg deficiency,supporting their functional involvement in ion homeostasis.Overall,our study strongly supports that TRAP-seq combined with RNA-seq followed by phenotype screening could facilitate the identification of novel players during stress responses.

Autophagy-related protein ATG5 regulates histone H2B mono-ubiquitylation by translational control of RNF20

Autophagy is an evolutionarily conserved lysosome-mediated catabolic process（Klionsky,2007）.Autophagy is believed to be essential for cell survival,especially when cells were exposed to stresses,such as nutrient starvation.

RNA-binding proteins in mouse male germline stem cells:a mammalian perspective

Adult stem cells that reside in particular types of tissues are responsible for tissue homeostasis and regeneration.Cellular functions of adult stem cells are intricately related to the gene expression programs in those cells.Past research has demonstrated that regulation of gene expression at the transcriptional level can decisively alter cell fate of stem cells.However,cellular contents of mRNAs are sometimes not equivalent to proteins,the functional units of cells.It is increasingly realized that post-transcriptional and translational regulation of gene expression are also fundamental for stem cell functions.Compared to differentiated somatic cells,effects on cellular status manifested by varied expression of RNA-binding proteins and global protein synthesis have been demonstrated in several stem cell systems.Through the cooperation of both cis-elements of mRNAs and trans-acting RNA-binding proteins that are intimately associated with them,regulation of localization,stability,and translational status of mRNAs directly influences the self-renewal and differentiation of stem cells.Previous studies have uncovered some of the molecular mechanisms that underlie the functions of RNA-binding proteins in stem cells in invertebrate species.However,their roles in adult stem cells in mammals are just beginning to be unveiled.This review highlights some of the RNA-binding proteins that play important functions during the maintenance and differentiation of mouse male germline stem cells,the adult stem cells in the male reproductive organ.

Identification of LepA as PPIase reveals a common molecular mechanism of translational GTPases regulating L11 switch on the ribosome

LepA, the highly conserved translational GTPase (trGTPase), triggers one-codon back-movement of the elongating ribosome. Here we identify a new enzymatic activity