Exogenous expression of caveolin‐1 is sufficient for hepatic stellate cell activation

Abstract

Caveolin‐1 (Cav‐1) expression is increased in hepatic stellate cells (HSC) upon liver cirrhosis and it functions as an integral membrane protein of lipid rafts and caveolae that regulates and integrates multiple signals as a platform. This study aimed to evaluate the role of Cav‐1 in HSC. Thus, the effects of exogenous expression of Cav‐1 in GRX cells, a model of activated HSC, were determined. Here, we demonstrated through evaluating well‐known HSC activation markers – such as α‐smooth muscle actin, collagen I, and glial fibrillary acidic protein – that up regulation of Cav‐1 induced GRX to a more activated phenotype. GRXEGFP‐Cav1 presented an increased migration, an altered adhesion pattern, a reorganization f‐actin cytoskeleton, an arrested cell cycle, a modified cellular ultrastructure, and a raised endocytic flux. Based on this, GRX EGFP‐Cav1 represents a new cellular model that can be an important tool for understanding of events related to HSC activation. Furthermore, our results reinforce the role of Cav‐1 as a molecular marker of HSC activation.

Endoglin Trafficking/Exosomal Targeting in Liver Cells Depends on N-Glycosylation

“…However, there is a higher abundance of Eng in raft fractions compared to non-raft fractions (Figure 1). The importance of Caveolin-1 (and therefore lipid rafts) for HSC activation and biology has been emphasized in recent study by others, showing that overexpression of Caveolin-1 in a HSC cell line (GRX) affected divers functions of HSC including activation, cell cycle, profibrogenic behavior and migration [54]. Therefore, we are currently investigating whether Eng overexpression or depletion in HSC as well as depletion of cholesterol changes the localization and distribution of the signaling receptor TβRI and TβRII and finally TGF-β-signaling in those subdomains.…”

Caveolin‐1 influences mitochondrial plasticity and function in hepatic stellate cell activation

“…This GRX cell line (Borojevic et al, 1985 ) is a relevant model to study the cellular mechanism of liver fibrosis once it can display an HSC quiescent‐like phenotype (Bitencourt et al, 2012 ; de Mesquita et al, 2013 ; Elias et al, 2019 ; Margis et al, 1992 ) or HSC activated‐like phenotype which is dependent on the environmental challenges (Guimaraes et al, 2006 ). We showed that exogenous expression of Cav‐1 was sufficient to induce classical parameters of activation, which highlights the potential role of Cav‐1 as a molecular effector of HSC transdifferentiation (Ilha et al, 2019 ). However, there are still gaps to fill regarding whether the expression of Cav‐1 interplay with parameters associated with the mitochondrial bioenergetic and dynamics and interorganelle communication, here namely as mitochondrial plasticity.…”

“…The GRX EGFP‐Cav1 cell line which constitutively overexpresses 83% more Cav‐1 protein and GRX EGFPpCineo , which contain the enhanced green fluorescence protein (EGFP) control used in this study were previously established by our group (Ilha et al, 2019 ).…”

“…Ultrafine cuts were obtained and counterstained with 1% uranyl acetate (Merck) and with 1% lead citrate (Merck). Ultrastructural imaging was obtained by transmission electron microscopy (TEM; JEM 1200 EXII; Jeol) at an 80‐kV acceleration voltage (Ilha et al, 2019 ).…”

“…For each sample, images of six fields were acquired and processed with Olympus FluoView FV1000 software. For LYSR, cell fluorescence intensity was analyzed using ImageJ (NIH; Ilha et al, 2019 ).…”