Research Of Transcription Factor CREB In Regulation Of TNFAIP1 Gene

Tumor necrosis factor, alpha-induced protein 1(TNFAIP1) was originally identified as a tumor necrosis factor alpha(TNF-α)-induced protein which involves in DNA replication or damage repair, cell apoptosis, control cytoskeleton structure and some Neurodegener-ative disease progress such as Alzheimer’s disease. CREB(c AMP response element-binding protein)is an important nuclear transcription factor that mediates multiple signal transduction pathways in the nervous system, and has an important regulation function in the growth, development, apoptosis, synapse plasticity, learning and memory of neurons.In the present study, we detected the effect of chemical compounds such as Forskolin, Genistein, Valproic acid and Polydatin on human TNFAIP1 gene expression in SKNSH cells. Forskolin was found to significantly reduce human TNFAIP1 mRNA levels, and human TNFAIP1 gene promoter activity. As forskolin is a stimulus of cAMP(Cyclic adenosine monophosphate), could potently stimulate the cAMP-CREB signaling pathway, so the regulation relationship between transcription factor CREB and TNFAIP1 gene was further investigated. Our result showed that KG-501, a specific CREB inhibitor, was able to increase TNFAIP1 protein. Overexpression of wildtype CREB, but not mutated CREBs133 a or KCREB significantly decreased human TNFAIP1 protein levels and TNFAIP1 gene promoter activity. In conclusion, our results suggested that CREB is a negative regulator of the TNFAIP1 gene expression, and the phosphorylation on Ser133 or the DNA binding of CREB would play an important role in the regulation of the TNFAIP1 gene expression by transcription factor CREB.Moreover, bioinformatics software was used to predicted the corresponding CREB binding sites in the proximal promoter region of TNFAIP1. Two cAMP response element(CRE)sites which are located at-50 and-196 of human TNFAIP1 gene promoter were identified. The deletion mutation of both CRE sites were markedly attenuated CREB-inhibited TNFAIP1 promoter activity. Furthermore, CREB could bind to the TNFAIP1 proximal promoter region spanning from – 290 to –5 that harbors both CRE sites were confirmed by Chromatin immunoprecipitation(CHIP). Our results suggested that CREB had a negative effect on the expression of the TNFAIP1 gene by binding to the CRE sites of the TNFAIP1 gene proximal promoter region, and CREB phosphorylation on Ser133 is responsible for forskolin-decreased TNFAIP1 expression.