Transcriptional regulation of the human RLIP76 gene




Sehrawat, Archana


Journal Title

Journal ISSN

Volume Title



A 76-kDa Ral-interacting protein (RLIP76) has been implicated in the pathogenesis of cancer and diabetes. It is often overexpressed in human malignant cell lines and human tumor samples and has been associated with metastasis and chemoresistance. RLIP76 homozygous knockout mice exhibit increased insulin sensitivity, hypoglycemia, and hypolipidemia, and resist cancer development. Little is known about the mechanism by which the expression of RLIP76 is regulated. In the present study, we functionally characterized the RLIP76 promoter using deletion mapping and mutational analysis to investigate the regulation of RLIP76 transcription. We have identified the promoter regions important for RLIP76 transcription, including a strong positive cis-acting element (-167 to -152) in the proximal promoter containing overlapping consensus cMYB and cETS binding sites. Transcription factor cMYB and the coactivator p300 associate with the RLIP76 gene promoter as shown by CHIP assay. Knockdown of p300 in cells reduces the activity of the promoter fragment containing wild type cMYB/cETS binding site in comparison to that with deleted or mutated cMYB/cETS binding site. Knockdown of p300 also decreases the RLIP76 expression as indicated by immunoblotting, immunocytochemistry and flow cytometry analysis. Thus, we report for the first time that p300 associates with the RLIP76 promoter via overlapping cMYB and cETS binding sites and regulates RLIP76 promoter activity and expression in HEK293 and MCF7 cells.