microRNA-199a-5p protects hepatocytes from bile acid-induced sustained endoplasmic reticulum stress

Abstract

Sustained endoplasmic reticulum (ER) stress has been linked to cell death and the pathogenesis of many liver diseases, including toxic liver, cholestasis, and infectious liver disease. The cellular pathways that attenuate hepatic ER stress have been the focus of many recent studies, but the role of microRNAs (miRNA) in this process remains unknown. Here, we report that one of the most abundant miRNAs in hepatocytes, miR-199a-5p, was elevated in both bile acid- and thapsigargin (TG)-stimulated cultured hepatocytes, as well as in the liver of bile duct-ligated mice. We identify the misfolded protein chaperone GRP78, as well as the unfolded protein response transducers endoplasmic reticulum to nucleus signaling 1 and activating transcription factor 6 as direct targets of miR-199a-5p, and show that endogenous miR-199a-5p represses the 3′ untranslated regions (UTRs) of their mRNAs. Through gain-of-function and loss of function approaches, we demonstrate that the elevated miR-199-5p disrupts sustained ER stress and prevents hepatocytes from undergoing bile acid- or TG-induced cell death. Furthermore, we reveal that the transcription factor AP-1 is a strong positive regulator of miR-199a-5p. In brief, our study demonstrates that AP-1/miR-199a-5p and ER stress mediators form a feedback loop, which shields hepatocytes from sustained ER stress and protects the liver from injury. On the basis of these findings, we also suggest that the miRNA miR-199a-5p is a potential target for clinical approaches aiming to protect hepatocytes in liver disease.

Downregulation of miR-384-5p attenuates rotenone-induced neurotoxicity in dopaminergic SH-SY5Y cells through inhibiting endoplasmic reticulum stress

“…In several cancer cell lines, GRP78 was reported to be regulated by miR-199a-5p as well as miR-30d and miR-181a and cooperatively suppressed GRP78-mediated chemoresistance (45). Similarly, Dai et al (5) reported that miR-199a-5p was evaluated during hepatic ER stress and directly regulated the expression of GRP78 in hepatocytes. Downregulation of miR-181b produced neuroprotection against ischemic injury via upregulating GRP78 (34).…”

“…Cells were exposed to rotenone (Sigma, St. Louis, MO) at various concentrations (1,5,10,20, and 50 M) (28) for the indicated times before being harvested for analysis. For miRNA transfection, cells were transfected with miR-384-5p mimics or inhibitors using Lipofectamine 2000 (Invitrogen) at a final concentration of 50 nM for 24 h prior to rotenone (20 M) exposure.…”

Inhibition of microRNA-199a-5p reduces the replication of HCV via regulating the pro-survival pathway

“…Recently, accumulating studies have highlighted the importance of cellular miRNAs in regulating HCV pathogenesis due to their versatility (Waldron and Holodniy, 2014). miR-199a-5p, a mature form of miR-199a, has been found to be effective in the inhibition of human hepatocellular carcinoma (Shen et al, 2010), in promoting liver repopulation (Mobus et al, 2014) and in hepatocyte protection (Dai et al, 2013), but little is known regarding its efficacy in HCV treatment. In the present study, we identified miR-199a-5p overexpression in HCV-infected cells and liver biopsy specimens, suggesting the potential function in the development of HCV infection.…”

Hepatoprotective effect of vitamin C on lithocholic acid-induced cholestatic liver injury in Gulo(−/−) mice

“…However, when vitamin C was supplied to Huh-BAT cells, this bile acid-induced reactive oxygen species production and apoptotic cell death were significantly attenuated. We then explored the possible mechanism of apoptosis attenuation by vitamin C and found that the activations of caspase 12, 3, 9 and 7 by bile acid were significantly attenuated by vitamin C, which suggested that activation of apoptotic signaling is ameliorated by vitamin C. Several studies have demonstrated that sustained ER stress has been linked to cell death and the pathogenesis of cholestatic liver diseases (Dai et al, 2013). In addition, our previous report (Jang et al, 2014) and others (Pastorekova et al, 2008;Szegezdi et al, 2006) showed that bile acid induced apoptosis through ER stress-related JNK activation.…”