| Summary: | 碩士 === 國立成功大學 === 生理學研究所 === 96 === Our previous studies have demonstrated that low-stiffness of collagen gel-induced epithelial cells apoptosis is mediated by deregulation of AP-1 proteins and endoplasmic reticulum stress-mediated disturbance of Ca2+ homeostasis. In order to elucidate to what extent and by what mechanism low rigidity induces apoptosis, we employed polyacrylamide (PA) gel to control substratum flexibility. We confirmed that low rigidity-induced apoptosis was only observed in epithelial cells. PA gel-induced apoptosis ratio was inversely correlated with substratum rigidity, and the threshold of substratum rigidity in triggering epithelial cell apoptosis was one thousand Pascal. In addition, low-rigidity of PA gel also induced c-Jun down-regulation, which is associated with c-Jun ubiquitination similar to the results observed by collagen gel. Interestingly, when cells were cultured on polyacrylamide gel, an increase in substratum rigidity augmented levels of c-Fos, JNK, and phosphorylation of JNK, unlike what was observed in cells cultured on collagen gel. Enhancement of substratum rigidity also up-regulated levels of c-Jun as well as phosphorylated c-Jun, which was dependent on JNK activation. In addition, augmentation of c-Jun phosphorylation by phosphatase inhibitor could prevent the degradation of c-Jun at various substratum rigidity. Taken together, these results indicate that low substratum rigidity triggers epithelial cell apoptosis through downregulation of JNK-c-Jun axis. As well as c-Jun ubiquitination and degradation, polyacrylamide gel elicits distinctive signal transduction mechanism from collagen gel.
|
|---|
