Anti-mTOR (S2442) Antibody (A25837)

Hepatic stellate cells (HSCs) are liver-specific pericytes that are recruited to vessels and secret pro-angiogenic cytokines, and thus actively involved in pathological vascularization during liver fibrosis. Peroxisome proliferator-activated receptor-γ (PPARγ) is a switch molecule controlling HSC activation. We investigated PPARγ regulation of angiogenic signal transduction and the molecular mechanisms involved in HSCs. Primary rat HSCs and liver sinusoidal endothelial cells (LSECs) were isolated and used in this study. Boyden chamber and tubulogenesis assays, identified that focal adhesion kinase (FAK)-RhoA signaling activated by platelet-derived growth factor (PDGF) was required for HSC motility and the associated vascularization. PDGF also stimulated vascular endothelial growth factor (VEGF) expression and HSC-driven vascularization through signals mediated by extracellular signal-regulated kinase (ERK) and mammalian target of rapamycin (mTOR). Gain- and loss-of-function analyses demonstrated that activation of PPARγ interrupted FAK-RhoA, ERK and mTOR cascades and inhibited HSC-based vascularization. Molecular evidence further revealed that PPARγ attenuation of HSC angiogenic properties was dependent on inhibition of PDGF-β receptor expression. We concluded that PPARγ inhibited angiogenic signal transduction through transrepression of PDGF-β receptor leading to reduced HSC motility, reduced VEGF expression, and thereby attenuated HSC-driven angiogenesis. PPARγ could be a molecular target for preventing vascular remolding in hepatic fibrosis.

Excessive βAR stimulation is an independent factor in inducing pathological cardiac hypertrophy. Here, we report miR-145 regulates both expression and localization of GATA6, thereby protecting the heart against cardiomyocyte hypertrophy induced by isoproterenol (ISO). The protective activity of miR-145 was associated with down-regulation of ANF, BNP and β-MHC expression, a decreased rate of protein synthesis, inhibited cardiomyocyte growth and the modulation of several signaling pathways including ERK1/2, JNK and Akt-GSK3β. The anti-hypertrophic effect was abrogated by exogenous over-expression of transcription factor GATA6 which was further identified as a direct target of miR-145. In addition, GSK3β antagonists, LiCl and TDZD8, restored the nuclear accumulation of GATA6, which was attenuated by miR-145 Finally, we observed a dynamic pattern of miR-145 expression in ISO-treated NRCMs and in the hearts of TAC mice. Together, our results identify miR-145 as an important regulator in cardiac hypertrophy.

Previous studies have demonstrated that wogonoside, a bioactive flavonoid extracted from the root of Scutellaria baicalensis Gerogi, has anti-inflammatory and anti-angiogenic activities. In this study, we evaluated wogonoside-induced autophagy on human breast MDA-MB-231 cells. We report that wogonoside triggered the formation of microtubule-associated protein-light chain 3 (MAP-LC3) positive autophagosomes and the accumulation of acidic vesicular and autolysosomes in MDA-MB-231 cells. In addition, cells treated by wogonoside developed autophagosome-like characteristics, including single and double membrane vacuoles containing intact and degraded cellular debris. The results showed that wogonoside promotes the expression of LC3-II and Beclin-1. Furthermore, wogonoside inhibited cell growth of MDA-MB-231 cells in a concentration- and time-dependent manner, which was associated with wogonoside-induced autophagy. Wogonoside also suppressed the activation of mammalian target of rapamycin (mTOR) and p70-S6 kinase (p70S6K) by regulating the expression of the extracellular signal-regulated kinase (ERK1/2) and p38 involved mitogen-activated protein kinase (MAPK) signaling pathway. Taken together, these results suggest that wogonoside partially inhibits MDA-MB-231 cell growth by inducing autophagy through the MAPK-mTOR pathway and may be a promising anti-tumor agent.