The forkhead transcription factor FOXO1 stimulates activity of mouse resistin gene promoter

• Main Authors: Shu-ya yang, 楊淑雅
• Other Authors: Yung-hsi Kao
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/05730363165916415735

碩士 === 國立中央大學 === 生命科學研究所 === 98 === Resistin is known as an adipocyte-specific secretory hormone that can cause insulin resistance and decrease adipocyte differentiation. It can be regulated by transcriptional factors, but the possible role of the forkhead transcription factor FOXO1 in regulating resistin gene expression is still unknown. Using NIH3T3 fibroblast, HEK293T, and C3H10T1/2 preadipocytes, we found that transient overexpression of a non-phosphorylatable, constitutively active FOXO1AAA activated resistin promoter-directed luciferase expression in a dose-dependent manner. Whereas, transient overexpression of either the wild type of FOXO1 or a DNA binding-deficient FOXO1H215R mutant was much less to increase luciferase expression. However, transient overexpression of a dominant-negative FOXO1△256 tended to inactivate resistin promoter activity. The FOXO1 protein target sites on resistin promoter were localized to the proximal -3546 to -788 bp of 5’-flanking region of the resistin promoter.In addition, FOXO1AAA and FOXO4AAA were more effective than FOXO3AAA and FOXO6T26A or FOXO6S184A in stimulating the resistin promoter-directed luciferase expression. Electrophoretic mobility shift assay indicated that glutathione-S-transferase-FOXO1 protein directly bound the nucleotide regions of resistin promoter at -1436 to -1387 and at -936 to -697. In vivo, levels of resistin mRNA and FOXO1 mRNA increased during differentiation of 3T3-L1 preadipocytes to adipocytes. These data suggest that FOXO1 transcription factor likely upregulates expression of preadipocyte resistin gene via activation of the upstream resistin promoter.