Glc7 Dephosphorylates Histone H3T11 And Regulates Autophagy And Telomere Silencing

Autophagy is an endogenous protective mechanism,which participates in cellular material synthesis,degradation and reuse to maintain normal physiological activities and homeostasis.It has gained widespread attention because it is related to various human diseases such as cancer,heart disease,and neurodegenerative diseases.Various histone modifications such as H4K16 acetylation and H3R17 dimethylation have been reported to regulate autophagy;however,it remains unclear about the effect of histone phosphorylation on autophagy and the underlying mechanism,especially for histone H3T11 phosphorylation which plays an important role in various biological processes such as serine metabolism and DNA damage repair.Here,using Saccharomyces cerevisiae as the model organism,we analyzed the effect of H3T11 phosphorylation on autophagy using a variety of molecular biological methods such as Western blot,immunofluorescence,Ch IP,fluorescence,etc.Our data showed that H3T11 phosphorylation can inhibit autophagy by down-regulating the transcription of autophagy genes.In addition,we found that pyruvate kinase Pyk1 can bind and phosphorylate H3T11 at ATG5,ATG8,ATG23 gene regions.However,the enzymes that dephosphorylate H3T11 have not been identified.Therefore,we carried out three rounds of Western blot screening based on the changes of histone H3T11 phosphorylation in yeast serine/threonine phosphoesterase mutant library and identified Glc7 is the enzyme that catalyzes histone HT11 dephosphorylation.We also confirmed the activity of Glc7 by in vitro enzyme reaction.In order to understand the biological functions of Glc7-mediated H3T11 dephosphorylation,we examined the effect of Glc7 on autophagy.The autophagy flux was reduced and the autophagy gene transcription was down-regulated in glc7-ts mutant,suggesting that Glc7 regulates the transcription of autophagy genes and thus affects autophagy process by dephosphorylating histone H3T11.Furthermore,telomeres in eukaryotes are typically heterochromatin structures that can suppress the expression of nearby genes,which is called telomere heterochromatin silencing.Using chromatin immunoprecipitation and real-time fluorescence quantitative PCR,we found that Glc7 can bind to telomere region and regulate telomere genes expression by dephosphorylating histone H3T11.To summarize,this study determined that SESAME phosphorylated H3T11 can inhibit autophagy by down-regulating autophagy genes transcription.Moreover,we identified the phosphatase Glc7 as an enzyme that dephosphorylates histone H3T11 and regulates cell autophagy and telomere silencing.All these data provide a new insight into studying the dynamic regulation mechanism of cell autophagy and telomere heterochromatin silencing.