Depletion of β‐arrestin2 in hepatic stellate cells reduces cell proliferation via ERK pathway

Abstract

β-Arrestins are multifunctional adaptor proteins. Recently, some new roles of β-arrestins in regulating intracellular signaling networks have been discovered, which regulate cell growth, proliferation, and apoptosis. Though, the role of β-arrestins expression in the pathology of hepatic fibrosis remains unclear. In this study, the possible relationship between the expression of β-arrestins with the experimental hepatic fibrosis and the proliferation of hepatic stellate cells (HSCs) were investigated. Porcine serum induced liver fibrosis was established in this study. At five time points, the dynamic expression of β-arrestin1, β-arrestin2, and α-smooth muscle actin (α-SMA) in rat liver tissues, was measured by immunohistochemical staining, double immunofluorescent staining, and Western blotting. This study showed that aggravation of hepatic fibrosis with gradually increasing expression of β-arrestin2 in the hepatic tissues, but not β-arrestin1. Further, as hepatic fibrosis worsens, β-arrestin2-expressing activated HSCs accounts for an increasingly larger percentage of all activated HSCs. And the expression of β-arrestin2 had a significant positive correlation with the expression of α-SMA, an activated HSCs marker. In vitro studies, the dynamic expression of β-arrestin1 and β-arrestin2 in platelet derived growth factor-BB (PDGF-BB) stimulated HSCs was assessed by Western blotting. The expression of β-arrestin2 was remarkably increased in PDGF-BB stimulated HSCs. Furthermore, the small interfering RNA (siRNA) technique was used to explore the effect of β-arrestins on the proliferation of HSCs and the activation of ERK1/2. Transfection of siRNA targeting β-arrestin2 mRNA (siβ-arrestin2) into HSCs led to a 68% and 70% reduction of β-arrestin2 mRNA and protein expression, respectively. siβ-arrestin2 abolished the effect of PDGF-BB on the proliferation of HSCs. In addition, siβ-arrestin2 exerted the inhibition of the activation of ERK1/2 in HSCs. The present study provided strong evidence for the participation of the β-arrestin2 in the pathogenesis of hepatic fibrosis. The β-arrestin2 depletion diminishes HSCs ERK1/2 signaling and proliferation stimulated by PDGF-BB. Selective targeting of β-arrestin2 inhibitors to HSCs might present as a novel strategy for the treatment of hepatic fibrosis.

MiR-29a and miR-652 Attenuate Liver Fibrosis by Inhibiting the Differentiation of CD4+ T Cells

“…β-arrestins belongs to the family of arrestin, the classical functions of β-arrestins are involved in the desensitization and recycling of G protein-coupled receptors (Smith and Rajagopal, 2016), while increasingly researchers suggested that β-arrestins also can to modulate intracellular functions, for example, Sun et al found that β-arrestin2 was involved in the proliferation of hepatic stellate cells via ERK pathway (Sun et al, 2013), while Li et al suggested that β-arrestin1 attenuate arthritis through impairing the differentiation of TH17 cell . β-arrestin1 was one member of β-arrestins, and functioned as multiprotein scaffolds in diverse cellular processes to modulate complex regulating pathways, such as cell proliferation and migration, as well as inflammatory reaction (Talbot et al, 2012;Li et al, 2013).…”

Deletion of β-Arrestin2 in Mice Limited Pancreatic β-Cell Expansion under Metabolic Stress through Activation of the JNK Pathway

“…βarr2 promotes proliferation in smooth muscle cells and hepatic stellate cells (12,13). Thus, we examined the effect of βarr2 on β-cell proliferation.…”

“…To analyze cell replication, barr2 The roles of βarr2 in the modulation of cell mass have been reported in smooth muscle and hepatic stellate cells (12,13). βarr2 aggravated atherosclerosis after carotid injury through mechanisms involving smooth muscle cell proliferation (12) and exacerbated hepatic fibrosis induced by porcine serum through its effect on hepatic stellate cell proliferation (13), suggesting a role of βarr2 regulation of cell mass expansion under environmental stress.…”

“…βarr2 aggravated atherosclerosis after carotid injury through mechanisms involving smooth muscle cell proliferation (12) and exacerbated hepatic fibrosis induced by porcine serum through its effect on hepatic stellate cell proliferation (13), suggesting a role of βarr2 regulation of cell mass expansion under environmental stress. Interestingly, Ravier et al reported recently that knocking out βarr2 in female mice decreased the β-cell mass (14).…”

“…For immunofluorescence analysis, pancreatic sections were incubated overnight at 4°C with guinea pig anti-insulin antibody (Abcam), followed by staining with secondary goat anti-guinea pig antibody conjugated with Alexa Fluor 488 (Invitrogen). Sections were imaged using a Zeiss AxioImager Standard Microscope (Carl Zeiss).To analyze cell replication, barr2 The roles of βarr2 in the modulation of cell mass have been reported in smooth muscle and hepatic stellate cells (12,13). βarr2 aggravated atherosclerosis after carotid injury through mechanisms involving smooth muscle cell proliferation (12) and exacerbated hepatic fibrosis induced by porcine serum through its effect on hepatic stellate cell proliferation (13), suggesting a role of βarr2 regulation of cell mass expansion under environmental stress.…”