mTOR-mediated transcriptional activity of TFEB/ZKSCAN3 involved in the autophagy suppression in mice liver at late stage of sepsis

• Main Authors: Ming-Hui Lin, 林明輝
• Other Authors: Chi-Huei Wang
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/62120950841250876369

碩士 === 高雄醫學大學 === 生物科技學系碩士班 === 104 === Sepsis-induced multiple organ failure (liver, lung, brain, heart and kidney) causes the high mortality in intensive care units. However, there is no effective therapy. Recently, autophagy induction has been reported to be a strategy for improving organ failure caused by sepsis. A transient increase of autophagy at early sepsis followed by autophagy suppression associated with functional failure at late sepsis was observed in rat liver. It remains unknown about what factors suppress autophagy in liver at late stage of sepsis. Previous reports indicated that hyperinsulinemia was observed in early stage of septic patients as well as in mouse model of sepsis by cecal ligation and puncture (CLP). Since, insulin inhibits hepatic autophagy, we hypothesize that early hyperinsulinemia suppresses autophagy at late sepsis via mTOR-dependent transcriptional regulation via TFEB/ZKSCAN3. C57BL/6J Narl mouse with CLP was used as septic model. Rapamycin (an mTOR inhibitor) was used to study the mediation of insulin/IRS1-PI3K-Akt-mTOR pathway in autophagy suppression at late sepsis. The results showed that, after CLP, the increase of mTOR phosphorylation at CLP9h was associated with the decline of autophagy from 12h to 15h after CLP. The nuclear translocation of TFEB was not significantly changed until CLP18h and the levels of target gene products (LC3 and p62) were not changed. While the level of ZKSCAN3 nuclear translocation was sequentially increased from CLP6h to CLP18h associated with a slightly repression of target gene product (WIPI2b) at CLP12h. Rapamycin pretreatment diminished the level of autophagy suppression at CLP15h, and slightly decreased the nuclear translocation of ZKSCAN3 associated with the relief of WIPI2b repression at CLP12h. These results suggest that mTOR-mediated TFEB/ZKSCAN3 transcriptional regulation participates in the autophagy suppression in liver at late stage of sepsis. Whether hyperinsulinemia plays a major role in activating IRS-1/PI3K-Akt-mTOR pathway and subsequent autophagy suppression at late sepsis is under investigation.