Cloning And Transcriptional Regulation Analysis Of The Tmepai Promoter

Transmembrane prostate androgen-induced protein(TMEPAI)is highly expressed in many tumor cells,however,little is known about the mechanisms regulating TMEPAI gene expression.It has been reported that TMEPAI is a target gene of the TGF-? signaling,expression of TMEPAI is induced by TGF-?.However,overexpression of TMEPAI negatively regulates the TGF-? signaling.It has been reported that TMEPAI is present on the lysosome and late endosome,and it inhibits TGF-? signaling by promoting lysosome degradation of the TpRI.To better understand the mechanisms regulating TMEPAI expression,in this study,we cloned and characterized the TMEPAI promoter.With luciferase assays and truncated assays,the sequence between-298 to +24 bp consists of the basal promoter activity for TMEPAI.Point mutation assays indicates that two Sp1 binding sites and a CREB binding site are crucial for maintaining the basal transcriptional activity of the TMEPAI promoter.Furthermore,to detect DNA methylation regulatory activity of the TMEPAI gene promoter,the luciferase plasmid of the TMEPAI promter was constructed.With luciferase report assay showed that DNA methylation of the TMEPAI promoter inhibited the TMEPAI promoter activity.Chromatin immunoprecipitation(ChIP)assays confirm the direct binding of Sp1 and CREB to the TMEPAI promoter.Sp1 or CREB overexpression and RNA interference experiments showed that Sp1 enhanced the transcription activity of the TMEPAI promoter and increased TMEPAI protein expression.In addition,Sp1 and CREB promote TMEPAI expression and TMEPAI-induced cell proliferation.Furthermore,Sp1 and CREB inhibit TGF-? signaling by regulating TMEPAI expression and contribute to tumorigenesis.Taken together,these results will help to understand the expression regulation of TMEPAI and its role in tumorigesis.Thus,TMEPAI might be used as a potential target for development to treat cancers.