Steviol stabilizes polycystin 1 expression and promotes lysosomal degradation of CFTR and beta-catenin proteins in renal epithelial cells
BIOMEDICINE & PHARMACOTHERAPY
Authors: Yuajit, Chaowalit; Muanprasat, Chatchai; Homvisasevongsa, Sureeporn; Chatsudthipong, Varanuj
Abstract
Malfunction of polycystin 1 (PC1) is linked to abnormally high epithelial cell proliferation and fluid secretion, eventually leading to renal cyst development and declined renal function as found in autosomal dominant polycystic kidney disease (ADPKD). Currently, there is no effective therapy for ADPKD. Recent studies report PC1 regulates CFTR chloride channels and beta-catenin levels in normal renal epithelial cells. Concurrently, our previous study found steviol retarded renal cyst enlargement in an in vitro and in an in vivo models by reducing CFTR expression and activity. Therefore, a potential relationship between steviol and PC1 is worthy of exploration. The present study was aimed to determine the effect of steviol on PC1, CFTR, and beta-catenin levels in renal epithelial cells with defective PC1 biogenesis and expression (Prkcsh(-/-) cell) and postnatal Pkd1 homozygous cell (Pkd1(-/-) cells). Using western blot analysis, it was found that steviol treatment at 100 mu M for 24-48 h substantially enhanced and stabilized PC1 C-terminal expression, while decreasing CFTR and beta-catenin protein expression in both Prkcsh(-/-) and Pkd1(-/-) cells. In addition, steviol promoted LAMP2 expression, a lysosomal enzyme marker. Interestingly, hydroxychloroquine (a lysosome inhibitor) treatment abolished steviol's effect in reducing CFTR and beta-catenin protein expression. Taken together, these findings suggest steviol slows cyst progression in cells and animal models of PKD, in part, by enhancing and stabilizing PC1 protein expression as well as by promoting lysosomal degradation of CFTR and beta-catenin. Therefore, steviol may represent a promising compound for treatment of polycystic kidney disease. (C) 2017 Elsevier Masson SAS. All rights reserved.
Ginsenoside Rh2 induces DNA damage and autophagy in vestibular schwannoma is dependent of LAMP2 transcriptional suppression
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Authors: Yang, Dong; Li, Xin; Zhang, Xiaoyan
Abstract
Ginsenoside Rh2 (G-Rh2), a component of ginseng extraction, exerted anti-tumor property in the occurrence and progress of human tumors. Vestibular schwannoma (VS) is a kind of benign tumor. Extraction of traditional Chinese herb has been applied to treat VS as adjuvant therapy. Nevertheless, G-Rh2-related molecular mechanisms in VS progress are not yet clear. The purpose of current study is to unveil the function and potential molecular mechanism of Rh2 in VS cellular functions. At first, the viability and apoptosis of VS cells treated with different concentrations of Rh2 were assessed. Autophagy and DNA damage response can be induced by multiple drugs. Here, we observed the changes of autophagy and DNA damage in Rh2-induced VS cells. Based on the experimental data, treatment with Rh2 contributed to cell apoptosis by inducing DNA damage and suppressing DNA damage. LAMP2 (lysosomal associated membrane protein 2), an autophagy inducer, was downregulated in Rh2-treated VS cells. Through mechanism study, we determined that Rh2 led to the transcriptional inactivation of LAMP2 by downregulating its transcription activator NR2F2 (nuclear receptor subfamily 2 group F member 2). In addition, NR2F2 overexpression recovered the role of Rh2 in cell functions, which was further rescued by the silence of LAMP2. Collectively, our study unveiled a novel NR2F2/LAMP2 axis in Rh2-mediated VS cells, which potentially contributes to the therapy for VS. (C) 2019 Elsevier Inc. All rights reserved.