The Transcription Regulation Of Sep15 Gene By HSF1

Selenium is an essential trace element for human health and it has been recognized as a component of several selenoproteins with crucial biological functions.15 kDa Selenoprotein(Sep15)is one of 25 human selenoproteins.To date,no available data about the transcriptional regulation and biological function of 15 kDa Selenoprotein(Sep15)have been found.In the present study,we will explore the transcriptional regulation of Sep15 and the role of Sep15 in the endoplasmic reticulum stress.Using bioinformatics,four HSF1-binding elements within the-2055/-248 oligonucleotide of the 5’-flanking region of the Sep15 gene were predicted,and were determined by chromatin immunoprecipitation assay(CHIP).It indicated that the transcription of human Sep15 may be regulated by HSF1.The activity of Sep15 promoter,the Sep15 mRNA levels and the expression of Sep15 were respectively detected by Dual-Luciferase Reporter Assay(DLR),real time PCR(Q-PCR)and western blot(WB)after overexpression of HSF1 in HEK293 T cells.The results showed that overexpression of HSF1 increased the activity of Sep15 promoter,enhanced the transcription of Sep15 and improved the expression of Sep15.Heat shock(HS)induces HSF1 from cytoplasm to nucleus.HEK293 T cells were exposured to heat shock(HS,43℃)for 1 hr,then using DLR,Q-PCR and WB to detecte the activity of Sep15 promoter,the Sep15 mRNA levels and the expression of Sep15,respectively.The results indicated HS increased the activity of Sep15 promoter,enhanced the transcription of Sep15 and improved the expression of Sep15.Tunicamycin(Tm)improved the expression of Sep15 and induced HSF1 to regulate relative gene expression.The activity of Sep15 promoter,the Sep15 mRNA levels and the expression of Sep15 in HEK293 T cells and N2 a cells in the response to ER stress induced by Tm were examined.Remarkably,while treatment with Tm upregulated Sep15 and triggered autophagy in both cells.This was associated with elevation in its m RNA expression that was caused by a transcriptional increase instead of changes in the stability of the mRNA,as indicated by its turnover rates,which remained similar in cells before and after treatment with Tm as show in actinomycin D-chasing assays.CHIP assay indicated there are five binding sites of HSF1 on Sep15 promoter,and one on the core region of Sep15 promoter.Collectively,these results identify overexpression of HSF1 or Tm-induced ER stress upregulated Sep15,which was caused by a transcriptional increase directly mediated by HSF1.The biological functions of Sep15 may be as an important prosurvival mechanism in both HEK293 T cells and N2 a cells induced by Tm through activation of autophagy.