Upregulation of histone H3 caused by CRYAA may contribute to the development of age-related cataract

Objective:Age-relate cataract(ARC)is a disease of the eyes with no effective drugs to prevent or treat patients.The aim of the present study is to determine whether histone H3,αA-crystallin(CRYAA),β-galactosidase(GLB1),and p53 are involved in the pathogenesis of ARC.Methods:A total of 99 anterior lens capsules(ALCs)of patients with ARC of various nuclear grades,ultraviolet models of ALCs,and two human lens epithelial cell lines(FHL-124 and SRA01/04)were used,and the expression of histone H3,CRYAA,GLB1,and p53 were detected by immunoblotting and reverse transcription and real time-quantitative polymerase chain reaction.The association between CRYAA with histone H3,GLB1,and p53 was assessed in FHL-124 and SRA01/04 cells following CRYAA overexpression.Results:Histone H3 and p53 in ALCs of patients with ARC were up-regulated in a grade-dependent manner,and the expression of CRYAA showed a positive association with histone H3,p53,and GLB1.In UV models of ALCs and human lens epithelial cell lines,the expression levels of histone H3,cell apoptosis factors(Bax/Bcl-2,cleaved caspase-3),and inflammation factors(interleukin-6,tumor necrosis factor-α)were all up-regulated.Furthermore,transfection of CRYAA in FHL-124 cells induced overexpression of histone H3.Conclusion:CRYAA-mediated upregulation of histone H3 may be involved in the pathogenesis of ARC.p53 may also have a role in ARC development,but not via the CRYAA-histone H3 axis.The results of the present study may assist in improving our understanding of the pathogenesis of ARC and in identifying potential targets for treatment.

Localization of Phosphorylated Histone H3 at Mitosis and Meiosis in Wheat

One of the prominent cell cycle related modifications of histone proteins, whose function is correlated with chromosome condensation, is the phosphorylation of histone H3. Wheat (Triticum aestivum L.) mitotic and meiotic cells were analyzed with indirect immunoflurorescence labeling with an antibody recognizing histone H3 phosphorylated at Serine 10 to study the localization of phosphorylated histone H3 at mitosis and meiosis. Our results showed that, during mitotic division, the phosphoryiation of H3 started from early prophase and vanished at telophase, remaining mainly in the pericentromeric regions at metaphase and anaphase. During meiotic division, phosphorylation of H3 initiated at the transition from leptotene to zygotene and remained uniform, along the chromosomes from prophase I until telophase whereas it showed slightly stronger in the pericentromeric regions than along the chromosome arms from metaphase II until Lelophase II The different patterns of H3 phophorylation at mitosis and meiosis in wheat suggested that this evolutionarily conserved post-translational chromatin modification might be involved in more roles besides chromosome condensation.

AOF1 is a histone H3K4 demethylase possessing demethylase activity-independent repression function

LSD1 （KDM1 under the new nomenclature） was the first identified lysine-specific histone demethylase belonging to the flavin-dependent amine oxidase family. Here, we report that AOF1 （KDM1B under the new nomenclature）, a mammalian protein related to LSD1, also possesses histone demethylase activity with specificity for H3K4mel and H3K4me2. Like LSD1, the highly conserved SWIRM domain is required for its enzymatic activity. However, AOF1 differs from LSD1 in several aspects. First, AOF1 does not appear to form stable protein complexes containing histone deacetylases. Second, AOF1 is found to localize to chromosomes during the mitotic phase of the cell cycle, whereas LSD1 does not. Third, AOF1 represses transcription when tethered to DNA and this repression activity is independent of its demethylase activity. Structural and functional analyses identified its unique N-terminal Zf-CW domain as essential for the demethylase activity-independent repression function. Collectively, our study identifies AOF1 as the second histone demethylase in the family of flavin-dependent amine oxidases and reveals a demethylase-independent repression function of AOF1.

EFFECTS OF CURCUMIN ON PROLIFERATION OF NB4 CELLS AND ACETYLATION OF HISTONE H3 AND P53

Objective: To investigate the effects of curcumin on the proliferation of NB4 cells and the acetylation of histone H3 and no-histone p53. Methods: NB4 cells were cultured and treated with or without curcumin at different concentration (50 μ mol/L, 25μ mol/L, 12.5μ mol/L, 6.25μ mol/L, 3.125μ mol/L) at various time points (oh, 4h, 8h, 12h, 24h). Western blot analysis was performed to determine the level of acetylated histone H3, p53 and acetylated p53, MTT assay was performed to examine the proliferation of NB4 cells. Results: the proliferation of NB4 cells was inhibited by curcumin in a time- and dose-dependent manner, the IC50 at 24h and 36h were 40μ mol/L and 25μ mol/L respectively. The levels of acetylated histone H3 and acetylated p53 were increased obviously. Conclusion: curcumin possessed the founction of deacetylases inhibitor, increased the level of acetylated histone H3 and the expression of tumor suppressor p53, enhanced later’s activity, and inhibited the proliferation of NB4 cell.

Di-and tri-methylation of histone H3K36 play distinct roles in DNA double-strand break repair

Histone H3 Lys36(H3K36)methylation and its associated modifiers are crucial for DNA double-strand break(DSB)repair,but the mechanism governing whether and how different H3K36 methylation forms impact repair pathways is unclear.Here,we unveil the distinct roles of H3K36 dimethylation(H3K36me2)and H3K36 trimethylation(H3K36me3)in DSB repair via non-homologous end joining(NHEJ)or homologous recombination(HR).Yeast cells lacking H3K36me2 or H3K36me3 exhibit reduced NHEJ or HR efficiency.y Ku70 and Rfa1 bind H3K36me2-or H3K36me3-modified peptides and chromatin,respectively.Disrupting these interactions impairs y Ku70 and Rfa1 recruitment to damaged H3K36me2-or H3K36me3-rich loci,increasing DNA damage sensitivity and decreasing repair efficiency.Conversely,H3K36me2-enriched intergenic regions and H3K36me3-enriched gene bodies independently recruit y Ku70 or Rfa1 under DSB stress.Importantly,human KU70 and RPA1,the homologs of y Ku70 and Rfa1,exclusively associate with H3K36me2 and H3K36me3 in a conserved manner.These findings provide valuable insights into how H3K36me2 and H3K36me3 regulate distinct DSB repair pathways,highlighting H3K36 methylation as a critical element in the choice of DSB repair pathway.

RNF187 governs the maintenance of mouse GC-2 cell development by facilitating histone H3 ubiquitination at K57/80

RING finger 187(RNF187),a ubiquitin-ligating(E3)enzyme,plays a crucial role in the proliferation of cancer cells.However,it remains unclear whether RNF187 exhibits comparable functionality in the development of germline cells.To investigate thepotential involvement of RNF187 in germ cell development,we conducted interference and overexpression assays using GC-2 cells,a mouse spermatocyte-derived cell line.Our findings reveal that the interaction between RNF187 and histone H3 increases theviability,proliferation,and migratory capacity of GC-2 cells.Moreover,we provide evidence demonstrating that RNF187 interactswith H3 and mediates the ubiquitination of H3 at lysine 57(K57)or lysine 80(K80),directly or indirectly resulting in increasedcellular transcription.This is a study to report the role of RNF187 in maintaining the development of GC-2 cells by mediatinghistone H3 ubiquitination,thus highlighting the involvement of the K57 and K80 residues of H3 in the epistatic regulation of genetranscription.These discoveries provide a new theoretical foundation for further comprehensive investigations into the functionof RNF187 in the reproductive system.

The histone H3 lysine-27 demethylase Jmjd3 plays a critical role in specific regulation of Th17 cell differentiation

Interleukin(IL)17-producing T helper(Th17)cells play critical roles in the clearance of extracellular bacteria and fungi as well as the pathogenesis of various autoimmune diseases,such as multiple sclerosis,psoriasis,and ulcerative colitis.Although a global transcriptional regulatory network of Th17 cell differentiation has been mapped recently,the participation of epigenetic modifications in the differentiation process has yet to be elucidated.We demonstrated here that histone H3 lysine-27(H3K27)demethylation,predominantly mediated by the H3K27 demethylase Jmjd3,crucially regulated Th17 cell differentiation.Activation of naı¨ve CD41 T cells immediately induced high expression of Jmjd3.Genetic depletion of Jmjd3 in CD41 T cells specifically impaired Th17 cell differentiation both in vitro and in vivo.Ectopic expression of Jmjd3 largely rescued the impaired differentiation of Th17 cells in vitro in Jmjd3-deficientCD41 T cells.Importantly,Jmjd3-deficient mice were resistant to the induction of experimental autoimmune encephalomyelitis(EAE).Furthermore,inhibition of the H3K27 demethylase activity with the specific inhibitor GSK-J4 dramatically suppressed Th17 cell differentiation in vitro.At the molecular level,Jmjd3 directly bound to and reduced the level of H3K27 trimethylation(me3)at the genomic sites ofRorc,which encodes the masterTh17 transcription factorRorgt,and Th17 cytokine genes such as Il17,Il17f,and Il22.Therefore,our studies established acritical role of Jmjd3-mediatedH3K27demethylation inTh17 cell differentiation andsuggest that Jmjd3 can be a novel therapeutic target for suppressing autoimmune responses.

AIMP1 promotes multiple myeloma malignancy through interacting with ANP32A to mediate histone H3 acetylation

Background:Multiple myeloma(MM)is the second most common hematological malignancy.An overwhelming majority of patients with MM progress to serious osteolytic bone disease.Aminoacyl-tRNA synthetase-interacting multifunctional protein 1(AIMP1)participates in several steps during cancer development and osteoclast differentiation.This study aimed to explore its role in MM.Methods:The gene expression profiling cohorts of MM were applied to determine the expression of AIMP1 and its association with MM patient prognosis.Enzyme-linked immunosorbent assay,immunohistochemistry,and Western blotting were used to detect AIMP1 expression.Protein chip analysis,RNA-sequencing,and chromatin immunoprecipitation and next-generation sequencing were employed to screen the interacting proteins and key downstream targets of AIMP1.The impact of AIMP1 on cellular proliferation was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay in vitro and a xenograft model in vivo.Bone lesions were evaluated using tartrate-resistant acid phosphatase staining in vitro.A NOD/SCID-TIBIA mouse model was used to evaluate the effect of siAIMP1-loaded exosomes on bone lesion formation in vivo.Results:AIMP1 expression was increased in MM patients and strongly associated with unfavorable outcomes.Increased AIMP1 expression promoted MM cell proliferation in vitro and in vivo via activation of the mitogen-activated protein kinase(MAPK)signaling pathway.Protein chip assays and subsequent experiments revealed that AIMP1 interacted with acidic leucine-rich nuclear phosphoprotein 32 family member A(ANP32A)to regulate histone H3 acetylation.In addition,AIMP1 increased histone H3 acetylation enrichment function of GRB2-associated and regulator of MAPK protein 2(GAREM2)to increase the phosphorylation of extracellular-regulated kinase 1/2(p-ERK1/2).Furthermore,AIMP1 promoted osteoclast differentiation by activating nuclear factor of activated T cells c1(NFATc1)in vitro.In contrast,exosome-coated small interfering RNA of AIMP1 effectively suppressed MM progression and osteoclast differentiation in vitro and in vivo.Conclusions:Our data demonstrate that AIMP1 is a novel regulator of histone H3 acetylation interacting with ANP32A in MM,which accelerates MM malignancy via activation of the MAPK signaling pathway.

The micronuclear histone H3 clipping in the unicellular eukaryote Tetrahymena thermophila

Clipping of the histone H3 N-terminal tail has been implicated in multiple fundamental biological processes for a growing list of eukaryotes.H3 clipping,serving as an irreversible process to permanently remove some post-translational modifications(PTMs),may lead to noticeable changes in chromatin dynamics or gene expression.The eukaryotic model organism Tetrahymena thermophila is among the first few eukaryotes that exhibits H3 clipping activity,wherein the first six amino acids of H3 are cleaved off during vegetative growth.Clipping only occurs in the transcriptionally silent micronucleus of the binucleated T.thermophila,thus offering a unique opportunity to reveal the role of H3 clipping in epigenetic regulation.However,the physiological functions of the truncated H3 and its protease(s)for clipping remain elusive.Here,we review the major findings of H3 clipping in T.thermophila and highlight its association with histone modifications and cell cycle regulation.We also summarize the functions and mechanisms of H3 clipping in other eukaryotes,focusing on the high diversity in terms of protease families and cleavage sites.Finally,we predict several protease candidates in T.thermophila and provide insights for future studies.

Structural basis for histone H3 recognition by NASP in Arabidopsis

The structural basis for histone recognition by the histone chaperone nuclear autoantigenic sperm protein(NASP)remains largely unclear.Here,we showed that Arabidopsis thaliana AtNASP is a monomer and displays robust nucleosome assembly activity in vitro.Examining the structure of AtNASP complexed with a histone H3α3 peptide revealed a binding mode that is conserved in human NASP.AtNASP recognizes the H3 N-terminal region distinct from human NASP.Moreover,AtNASP forms a co-chaperone complex with ANTI-SILENCING FUNCTION 1 ASF1 by binding to the H3 Nterminal region.Therefore,we deciphered the structure of AtNASP and the basis of the AtNASP-H3 interaction.

Npac Is A Co-factor of Histone H3K36me3 and Regulates Transcriptional Elongation in Mouse Embryonic Stem Cells

Chromatin modification contributes to pluripotency maintenance in embryonic stem cells(ESCs).However,the related mechanisms remain obscure.Here,we show that Npac,a"reader"of histone H3 lysine 36 trimethylation(H3K36me3),is required to maintain mouse ESC(mESC)pluripotency since knockdown of Npac causes mESC differentiation.Depletion of Npac in mouse embryonic fibroblasts(MEFs)inhibits reprogramming efficiency.Furthermore,our chromatin immunoprecipitation followed by sequencing(ChIP-seq)results of Npac reveal that Npac co-localizes with histone H3K36me3 in gene bodies of actively transcribed genes in mESCs.Interestingly,we find that Npac interacts with positive transcription elongation factor b(p-TEFb),Ser2-phosphorylated RNA PolⅡ(RNA PolⅡSer2P),and Ser5-phosphorylated RNA PolⅡ(RNA PolⅡSer5 P).Furthermore,depletion of Npac disrupts transcriptional elongation of the pluripotency genes Nanog and Rif1.Taken together,we propose that Npac is essential for the transcriptional elongation of pluripotency genes by recruiting p-TEFb and interacting with RNA PolⅡSer2P and Ser5P.

Cellular functions of MLL/SET-family histone H3 lysine 4 methyltransferase components

The MLL/SET family of histone H3 lysine 4 methyltransferases form enzyme complexes with core subunits ASH2L, WDR5, RbBP5, and DPY-30 （often abbreviated WRAD）, and are responsible for global histone H3 iysine 4 methylation, a hallmark of actively transcribed chromatin in mammalian cells. Accordingly, the function of these proteins is required for a wide variety of processes including stem cell differentiation, cell growth and division, body segmentation, and hematopoiesis. While most work on MLL-WRAD has focused on the function this core complex in histone methylation, recent studies indicate that MLL-WRAD proteins interact with a variety of other proteins and IncRNAs and can localize to cellular organelles beyond the nucleus. In this review, we focus on the recently described activities and interacting partners of MLL-WRAD both inside and outside the nucleus.

Effects of B[a]P-UVA Co-Exposure on Epigenetic Marks of Isolated Skin Cells and Impact of an Arundo donax L. Extract of These Changes

Background: Extrinsic aging results from environmental stressors such as UVR or pollutants. While the effects of single pollutants are better understood, those of their combination remain poorly scrutinized. Objective: Building on a study showing downregulation of several processes upon co-exposure to B[a]P and UVA, we investigated changes induced by epigenetic marks. Materials and Methods: Human primary fibroblasts and HaCaT cells were exposed to B[a]P and UVA. After 24 hours, exposed and unexposed cells were compared to assess DNA methylation. Focusing on HaCaT, multiplex assays enabled quantifying histone H3 modifications and evaluating four splicing factors (SRSF1, SRSF3, SFPQ, and SF3B1) by immunohistochemical labeling. The expression of keratinocyte-/fibroblast-relevant genes was assessed by RT-qPCR. Finally, the impact of an Arundo donax L. extract added 24 hours before B[a]P-UVA co-exposure was analyzed. Results: Exposure to B[a]P-UVA raised DNA methylation (HaCaT: ×3.6, fibroblasts: ×1.9), an increase prevented by the extract. In HaCaT cells, B[a]P-UVA increases the frequency of S10P (+38%). When exposure was preceded by extract treatment, the frequency of several methylations was impacted. B[a]P-UVA only induced the expression of SRSF1 and SFPQ in HaCaT (+46% and +34%). Treatment with the extract abolished this effect. Co-exposure increases the expression of inflammation-related genes (IL-1α, IL-1β) in HaCaT cells and decreases those of AQP3, KRT15, and SOD2. The extract has little effect on these changes. In primary fibroblasts, exposure to B[a]P-UVA lowered the expression of LOXL2, LUM, and TGFBR2 (−38%, −59%, and −51%, respectively), and the extract did not affect these modifications. Conclusion: Within 24 hours, a single B[a]P-UVA co-exposure changes epigenetic marks of skin cells but has only mild effects on gene expression. An Arundo donax L. extract can prevent part of the epigenetic marks’ changes and could stimulate the expression of some genes in primary fibroblasts.

Gastric cancer cell lines induced by trichostatin A

AIM： To explore the effect of trichostatin A （TSA） on apoptosis and acetylated histone H3 levels in gastric cancer cell lines BGC-823 and SGC-7901. METHODS： The effect of TSA on growth inhibition and apoptosis was examined by MTT, fluorescence microscopy and PI single-labeled flow cytometry. The acetylated histone H3 level was detected by Western blot. RESULTS： TSA induced apoptosis in gastric cancer cell lines BGC-823 and SGC-7901 was in a dose and time-dependent manner. Apoptotic cells varied significantly between TSA treated groups （37.5 ng/mL 72 h for BGC-823 cell line and 75 ng/mL 72 h for SGC-7901 cell line） and control group （0.85 ± 0.14 vs 1.14 ± 0.07, P = 0.02; 0.94 ± 0.07 vs 1.15 ± 0.06, P = 0.02）. Morphologic changes of apoptosis, including nuclear chromatin condensation and fluorescence strength, were observed under fluorescence microscopy. TSA treatment in BGC-823 and SGC-7901 cell lines obviously induced cell apoptosis, which was demonstrated by the increased percentage of sub-G1 phase cells, the reduction of Gl-phase cells and the increase of apoptosis rates in flow cytometric analysis. The result of Western blot showed that the expression of acetylated histone H3 increased in BGC-823 and SGC-7901 TSA treatment groups as compared with the control group.CONCLUSION： TSA can induce cell apoptosis in BGC-823 and SGC-7901 cell lines. The expression of acetylated histone H3 might be correlated with apoptosis.

Histone 3 lysine 36 to methionine mutations stably interact with and sequester SDG8 in Arabidopsis thaliana

Post-transcriptional modifications of histones play important roles in various biological processes. Here, we report that Arabidopsis plants overexpressing histone H3 lysine to methionine mutations at histone H3.1K36(H3.1K36M) and H3.3K36(H3.3K36M) have serious developmental defects with early-flowering and change in the modifications of endogenous histone H3, including acetylation at lysine 9(H3K9ac), trimethylation at lysine 27(H3K27me3), di-and tri-methylation at lysine 36(H3K36me2 and H3K36me3). In addition, H3K36M mutation alters its subcellular localization and interacts with H3K36 methyltransferase SDG8. Our results support a model in which H3K36M stably interacts with SDG8, and inhibits the activity of SDG8 by sequestering SDG8, resulting in a dominant negative effect to affect the proper expression levels of a variety of genes and plant development.

Total chemical synthesis of bivalently modified H3 by improved three-segment native chemical ligation

The H3 bivalent modifications of trimethylationat Lys9 and acetylation at Lys18(H3-K9 Me3-K18 Ac) were identified to collectively recruit TRIM33 in the nodal signaling pathway.To understand the underlying mechanism of TRIM33 recruitment,the nucleosome core particles(NCPs) containing full-length H3-K9 Me3-K18 Ac were indispensable samples.Herein we developed a pseudo dipeptide strategy to efficiently prepare peptide segments,facilitating the chemical synthesis of H3-K9 Me3-K18 Ac at a tens of milligram scale.The synthetic H3-K9 Me3-K18 Ac was then examined by CD spectroscopy,which demonstrated a prominent shift compared to recombinant H3.Finally,bivalently modified NCPs were assembled and verified by gel mobility shift assay with good homogeneity.

ERα promotes transcription of tumor suppressor gene ApoA-I by establishing H3K27ac-enriched chromatin microenvironment in breast cancer cells

Apolipoprotein A-I(Apo A-I),the main protein component of high-density lipoprotein(HDL),plays a pivotal role in reverse cholesterol transport(RCT).Previous studies indicated a reduction of serum Apo A-I levels in various types of cancer,suggesting Apo A-I as a potential cancer biomarker.Herein,ectopically overexpressed Apo A-I in MDA-MB-231 breast cancer cells was observed to have antitumor effects,inhibiting cell proliferation and migration.Subsequent studies on the mechanism of expression regulation revealed that estradiol(E2)/estrogen receptorα(ERα)signaling activates Apo A-I gene transcription in breast cancer cells.Mechanistically,our Ch IP-seq data showed that ERαdirectly binds to the estrogen response element(ERE)site within the Apo A-I gene and establishes an acetylation of histone 3 lysine 27(H3 K27 ac)-enriched chromatin microenvironment.Conversely,Fulvestrant(ICI 182780)treatment blocked ERαbinding to ERE within the Apo A-I gene and downregulated the H3 K27 ac level on the Apo A-I gene.Treatment with p300 inhibitor also significantly decreased the Apo A-I messenger RNA(m RNA)level in MCF7 cells.Furthermore,the analysis of data from The Cancer Genome Atlas(TCGA)revealed a positive correlation between ERαand Apo A-I expression in breast cancer tissues.Taken together,our study not only revealed the antitumor potential of Apo A-I at the cellular level,but also found that ERαpromotes the transcription of Apo A-I gene through direct genomic effects,and p300 may act as a co-activator of ERαin this process.

Exogenous artificial DNA forms chromatin structure with active transcription in yeast

Yeast artificial chromosomes(YACs) are important tools for sequencing,gene cloning,and transferring large quantities of genetic information.However,the structure and activity of YAC chromatin,as well as the unintended impacts of introducing foreign DNA sequences on DNA-associated biochemical events,have not been widely explored.Here,we showed that abundant genetic elements like TATA box and transcription factor-binding motifs occurred unintentionally in a previously reported datacarrying chromosome(d Chr).In addition,we used state-of-the-art sequencing technologies to comprehensively profile the genetic,epigenetic,transcriptional,and proteomic characteristics of the exogenous d Chr.We found that the data-carrying DNA formed active chromatin with high chromatin accessibility and H3K4 tri-methylation levels.The d Chr also displayed highly pervasive transcriptional ability and transcribed hundreds of noncoding RNAs.The results demonstrated that exogenous artificial chromosomes formed chromatin structures and did not remain as naked or loose plasmids.A better understanding of the YAC chromatin nature will improve our ability to design better data-storage chromosomes.

Regulation of Torpor in the Gray Mouse Lemur:Transcriptional and Translational Controls and Role of AMPK Signaling

The gray mouse lemur（Microcebus murinus） is one of few primate species that is able to enter daily torpor or prolonged hibernation in response to environmental stresses. With an emerging significance to human health research, lemurs present an optimal model for exploring molecular adaptations that regulate primate hypometabolism. A fundamental challenge is how to effectively regulate energy expensive cellular processes（e.g., transcription and translation） during transitionsto/from torpor without disrupting cellular homeostasis. One such regulatory mechanism is reversible posttranslational modification of selected protein targets that offers fine cellular control without the energetic burden. This study investigates the role of phosphorylation and/or acetylation in regulating key factors involved in energy homeostasis（AMP-activated protein kinase, or AMPK, signaling pathway）, m RNA translation（eukaryotic initiation factor 2a or e IF2 a, eukaryotic initiation factor 4E or e IF4 E, and initiation factor 4E binding protein or 4EBP）, and gene transcription（histone H3） in six tissues of torpid and aroused gray mouse lemurs. Our results indicated selective tissue-specific changes of these regulatory proteins. The relative level of Thr172-phosphorylated AMPKa was significantly elevated in the heart but reduced in brown adipose tissue during daily torpor, as compared to the aroused lemurs, implicating the regulation of AMPK activity during daily torpor in these tissues. Interestingly, the levels of the phosphorylated e IFs were largely unaltered between aroused and torpid animals. Phosphorylation and acetylation of histone H3 were examined as a marker for transcriptional regulation. Compared to the aroused lemurs, level of Ser10-phosphorylated histone H3 decreased significantly in white adipose tissue during torpor, suggesting global suppression of gene transcription. However, a significant increase in acetyl-histone H3 in the heart of torpid lemurs indicated a possible stimulation of transcriptional activity of this tissue. Overall, our study demonstrates that AMPK signaling and posttranslational regulation of selected proteins may play crucial roles in the control of transcription/translation during daily torpor in mouse lemurs.

Abnormal expression of TFIIIB subunits and RNA PolⅢgenes is associated with hepatocellular carcinoma

The levels of the products of RNA polymeraseⅢ-dependent genes(PolⅢgenes),including tRNAs and 5S rRNA,are elevated in transformed and tumor cells,which potentiate tumorigenesis.TFIIB-related factor 1(Brf1)is a key transcription factor and specifically regulates the transcription of PolⅢgenes.In vivo and in vitro studies have demonstrated that a decrease in Brf1 reduces PolⅢgene transcription and is sufficient for inhibiting cell transformation and tumor formation.Emerging evidence indicates that dysregulation of Brf1 and PolⅢgenes is linked to the development of hepatocellular carcinoma(HCC)in humans and animals.We have reported that Brf1 is overexpressed in human liver cancer patients and that those with high Brf1 levels have shorter survivals.This review summarizes the effects of dysregulation of these genes on HCC and their regulation by signaling pathways and epigenetics.These novel data should help us determine the molecular mechanisms of HCC from a different perspective and guide the development of therapeutic approaches for HCC patients.