GATA Factor ELT-2 Regulates Ogt-1 Transcription And Affects Lifespan In C.elegans

O-linked-?-N-acetylglucosamine(O-GlcNAc)modification is a dynamic,reversible post-translational modification which is widely found in animals and plant cells.In the metazoans,O-GlcNAc modification is regulated by two enzymes,O-GlcNAc transferase(OGT)and N-acetylcitaminase(O-GlcNAcase,OGA).OGT utilizes UDP-GlcNAc as a donor to catalyze addition of O-GlcNAc on serine and threonine residues of target proteins.OGA is responsible for removing O-GlcNAc modification.It has been found that thousands of nuclear and cytoplasmic proteins are modified by O-GlcNAc,which plays important roles in a variety of cellular pathways,including signal transduction,cell differentiation,stress response and transcriptional regulation.Moreover,the abnormal O-GlcNAc modification level had been found associated with a variety of human diseases,such as Alzheimer's disease,type II diabetes,and cancer.Caenorhabditis elegans(C.elegans)is a good model in scientific research.The homologs of mammalian OGT and OGA in C.elegans are OGT-1 and OGA-1.Evidences has shown that nematode OGT-1 and OGA-1 are involved in controlling lifespan,nutrient storage,dauer formation,innate immune response,autophagy.Our previous studies have also found that OGT-1 promotes lifespan and oxidative stress resistance by O-GlcNAc modification on transcription factor SKN-1.These findings suggest that OGT-1 is a key factor in regulating lifespan.Therefore,we intend to study whether the expression level of OGT-1 is changed in aging process.By monitoring OGT-1:GFP expression on confocal microscopy,we observed the expression level of OGT-1 in intesitine and phaynx was decreased with aging.This Evidence indicates that the expression of OGT-1 is likely to be regulated by some transcription factors.In order to study the molecular mechanism of ogt-1 gene regulation,we first predicted the potential transcription factors binding on ogt-1 promoter by MATCH software(http://www.gene-regulation.com).The results showed that GATA transcription factors are most likely to bind of ogt-1 promoter.C.elegans GATA transcription factor ELT-2 is well-known expressed specifically in the intestinal nuclei and play key roles in regulating intestinal terminal differentiation,functional maintenance and lifespan.Therefore,we next investigated whether transcription factor ELT-2 is involved in ogt-1 gene regulation.By RT-PCR and Western Blot,we first found that elt-2 RNAi significantly reduced ogt-1 mRNA and protein expression level.Then,the luciferase reporter assay and EMSA results showed that ELT-2 activated ogt-1 promoter by their specific binding each other.Finally,we found that elt-2 RNAi significantly reduced the global O-GlcNAc level in wild-type worms and affected the function of ogt-1 on modulating lifespan.Taken together,our results indicate GATA transcription factor ELT-2 regulates ogt-1 gene transcription and influences its function of regulating lifespan in C.elegans.These findings have a key implication in investigating the role of mammalian GATA factors on modulating OGT activity involved in human aging-related diseases.