Increased contractility of hepatic stellate cells in cirrhosis is mediated by enhanced Ca2+-dependent and Ca2+-sensitization pathways

2011 ◽  
Vol 300 (6) ◽  
pp. G1010-G1021 ◽  
Author(s):  
Masateru Iizuka ◽  
Takahisa Murata ◽  
Masatoshi Hori ◽  
Hiroshi Ozaki
Keyword(s):  
Smooth Muscle ◽  
Hepatic Stellate Cells ◽  
Smooth Muscle Actin ◽  
Stellate Cells ◽  
Regulatory Proteins ◽  
Muscle Actin ◽  
Rock Inhibitor ◽  
Duct Ligation

Activation of hepatic stellate cells (HSCs) results in cirrhosis and portal hypertension due to intrahepatic resistance. Activated HSCs increase their contraction after receptor agonist stimulation; however, the signaling pathways for the regulation of contraction are not fully understood. The aim of this study was to elucidate the change in contractile mechanisms of HSCs after cirrhotic activation. The expression pattern of contractile regulatory proteins was analyzed with quantitative RT-PCR and Western blotting. The phosphorylation levels of myosin light chain (MLC), 17-kDa PKC-potentiated protein phosphatase 1 inhibitor protein (CPI-17), and MLC phosphatase targeting subunit 1 (MYPT1) after endothelin-1 (ET-1) stimulation in culture-activated HSCs were measured using phosphorylation-specific antibodies. In vivo-activated HSCs were isolated from rats subjected to bile duct ligation and repeated dimethylnitrosoamine injections. HSCs showed increased expression of not only α-smooth muscle actin, but also the contractile regulatory proteins MLC kinase (MLCK), Rho kinase 2 (ROCK2), and CPI-17 during HSC activation in vitro. In culture-activated HSCs, ET-1 increased phosphorylation of CPI-17 at Thr18, which was markedly inhibited by the PKC inhibitor Ro-31–8425. ET-1 induced phosphorylation of MYPT1 at Thr853, which was suppressed by the ROCK inhibitor Y-27632. ET-1 induced sustained phosphorylation of MLC at Thr18/Ser19, which was inhibited by both Ro-31–8425 and Y-27632. Consistent with the data obtained from the in vitro study, HSCs isolated from cirrhotic rats showed increased expression of α-smooth muscle actin, MLCK, CPI-17, and ROCK2 compared with HSCs from nontreated rats. Furthermore, MLC phosphorylation in in vivo-activated HSCs was increased, according to enhanced phosphorylation of CPI-17 and MYPT1 in the presence of ET-1. These results suggest that activated HSCs may participate in constriction of hepatic sinusoids in the cirrhotic liver through both Ca2+-dependent (MLCK pathway) and Ca2+-sensitization mechanism (CPI-17 and MYPT1 pathways).

scholarly journals Conophylline Suppresses Pancreatic Stellate Cells and Improves Islet Fibrosis in Goto-Kakizaki Rats

Endocrinology ◽  
2012 ◽  
Vol 153 (2) ◽  
pp. 621-630 ◽  
Author(s):  
Rie Saito ◽  
Satoko Yamada ◽  
Yoritsuna Yamamoto ◽  
Tsutomu Kodera ◽  
Akemi Hara ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Actin ◽  
Stellate Cells ◽  
Activin A ◽  
Pancreatic Stellate Cells ◽  
Muscle Actin ◽  
Β Cell ◽  
Gk Rats

Activin A is a differentiation factor for β-cells and is effective to promote β-cell neogenesis. Activin A is also an autocrine activator of pancreatic stellate cells, which play a critical role in fibrogenesis of the pancreas. Conophylline (CnP) is a natural compound, which reproduces the effect of activin on β-cell differentiation and promotes β-cell neogenesis when administered in vivo. However, its effect on stellate cells is not known. We therefore investigated the effect of CnP on stellate cells both in vitro and in vivo. Unlike activin A, CnP inhibited activation of cultured stellate cells and reduced the production of collagen. We then analyzed the involvement of stellate cells in islet fibrosis in Goto-Kakizaki (GK) rats, a model of type 2 diabetes mellitus. In pancreatic sections obtained from 6-wk-old GK rats, CD68-positive macrophages and glial fibrillary acidic protein- and α-smooth muscle actin-positive stellate cells infiltrated into islets. Later, the number of macrophages was increased, and the α-smooth muscle actin staining of stellate cells became stronger, indicating the involvement of stellate cells in islet fibrosis in GK rats. When CnP was administered orally for 4 wk, starting from 6 wk of age, invasion of stellate cells and macrophages was markedly reduced and islet fibrosis was significantly improved. The insulin content was twice as high in CnP-treated rats. These results indicate that CnP exerts antifibrotic actions both in vitro and in vivo and improves islet fibrosis in Goto-Kakizaki rats.

The hepatitis C virus core protein indirectly induces alpha-smooth muscle actin expression in hepatic stellate cells via interleukin-8

2010 ◽  
Vol 52 (5) ◽  
pp. 635-643 ◽  
Author(s):  
Sophie Clément ◽  
Stéphanie Pascarella ◽  
Stéphanie Conzelmann ◽  
Carmen Gonelle-Gispert ◽  
Kévin Guilloux ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Hepatitis C ◽  
Hepatic Stellate Cells ◽  
Core Protein ◽  
Smooth Muscle Actin ◽  
Stellate Cells ◽  
Muscle Actin ◽  
Alpha Smooth Muscle Actin ◽  
Virus Core ◽  
Actin Expression

scholarly journals Combination of 13-Cis Retinoic Acid and Lovastatin: Marked Antitumor Potential In Vivo in a Pheochromocytoma Allograft Model in Female Athymic Nude Mice

Endocrinology ◽  
2014 ◽  
Vol 155 (7) ◽  
pp. 2377-2390 ◽  
Author(s):  
Svenja Nölting ◽  
Alessio Giubellino ◽  
Yasin Tayem ◽  
Karen Young ◽  
Michael Lauseker ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Retinoic Acid ◽  
Smooth Muscle Actin ◽  
Treated Group ◽  
Muscle Actin ◽  
Tumor Mass ◽  
Viable Tumor ◽  
Over Time

Currently, there are no reliably effective therapeutic options for metastatic pheochromocytoma (PCC) and paraganglioma. Moreover, there are no therapies that may prevent the onset or progression of tumors in patients with succinate dehydrogenase type B mutations, which are associated with very aggressive tumors. Therefore, we tested the approved and well-tolerated drugs lovastatin and 13-cis-retinoic acid (13cRA) in vitro in an aggressive PCC mouse cell line, mouse tumor tissue-derived (MTT) cells, and in vivo in a PCC allograft nude mouse model, in therapeutically relevant doses. Treatment was started 24 hours before sc tumor cell injection and continued for 30 more days. Tumor sizes were measured from outside by caliper and sizes of viable tumor mass by bioluminescence imaging. Lovastatin showed antiproliferative effects in vitro and led to significantly smaller tumor sizes in vivo compared with vehicle treatment. 13cRA promoted tumor cell growth in vitro and led to significantly larger viable tumor mass and significantly faster increase of viable tumor mass in vivo over time compared with vehicle, lovastatin, and combination treatment. However, when combined with lovastatin, 13cRA enhanced the antiproliferative effect of lovastatin in vivo. The combination-treated mice showed slowest tumor growth of all groups with significantly slower tumor growth compared with the vehicle-treated mice and significantly smaller tumor sizes. Moreover, the combination-treated group displayed the smallest size of viable tumor mass and the slowest increase in viable tumor mass over time of all groups, with a significant difference compared with the vehicle- and 13cRA-treated group. The combination-treated tumors showed highest extent of necrosis, lowest median microvessel density and highest expression of α-smooth muscle actin. The combination of high microvessel density and low α-smooth muscle actin is a predictor of poor prognosis in other tumor entities. Therefore, this drug combination may be a well-tolerated novel therapeutic or preventive option for malignant PCC.

scholarly journals Structural Changes and Detection of Liver Fibrosis–Related Protein Levels in Coculture of Alveolar Echinococcosis-Protoscoleces and Human Hepatic Stellate Cells

2021 ◽  
Author(s):  
DEping cao ◽  
Emad Shamsan ◽  
Bofan Jiang ◽  
Zhang Yaogang ◽  
Mustafa Abdo Saif Dehwah
Keyword(s):  
Smooth Muscle ◽  
Liver Fibrosis ◽  
Hepatic Stellate Cells ◽  
Structural Changes ◽  
Alveolar Echinococcosis ◽  
Smooth Muscle Actin ◽  
Stellate Cells ◽  
Enzyme Linked Immunosorbent Assay ◽  
Muscle Actin ◽  
Related Protein

Abstract BackgroundEchinococcus multilocularis is a causative agent of human alveolar echinococcosis (AE). AE leads to cirrhosis in several organs, such as the liver, triggering severe conditions, including hepatic failure and encephalopathy. The main purpose of this study is to explore the interaction between treated hepatic stellate cells and AE-protoscoleces (AE-PSCs). The results of this study will be provided experimental basis for revealing the mechanisms of hepatic fibrosis after AE infection.MethodsWe investigated the role of alveolar echinococcosis-protoscoleces (AE-PSCs) in liver fibrosis and structural changes and liver fibrosis-related protein expression in a coculture of PSCs and human hepatic stellate cells (HSCs). Structural changes were detected by transmission electron microscopy, whereas liver fibrosis-related proteins, collagen I, alpha-smooth muscle actin, and osteopontin levels were measured by western blotting and enzyme-linked immunosorbent assay. ResultsPSCs exhibited morphological changes, specifically changes in shape, and showed slight changes in the cytoplasmic membrane, whereas structural modifications were observed in HSCs. Additionally, western blotting and enzyme-linked immunosorbent assay revealed that PSCs treated in vitro with HSC-LX2 showed significantly increased collagen-Ⅰ, α-smooth muscle actin, and osteopontin expression levels after 3–4 days of incubation in a coculture system. AE-PSCs induced liver fibrosis by inducing extracellular matrix expression and HSC activation.ConclusionsThese results provide insight into the pathogenesis of echinococcosis- induced hepatic fibrosis and introduce therapeutic targets and diagnostic criteria for managing echinococcosis-dependent liver fibrosis.

c-Myb modulates transcription of the α-smooth muscle actin gene in activated hepatic stellate cells

2000 ◽  
Vol 278 (2) ◽  
pp. G321-G328 ◽  
Author(s):  
Martina Buck ◽  
Dong Joon Kim ◽  
Karl Houglum ◽  
Tarek Hassanein ◽  
Mario Chojkier
Keyword(s):  
Smooth Muscle ◽  
Hepatic Stellate Cells ◽  
Cell Activation ◽  
Stellate Cell ◽  
Smooth Muscle Actin ◽  
Stellate Cells ◽  
Dominant Negative ◽  
Muscle Actin ◽  
Muscle Actin Gene ◽  
High Level

Expression of α-smooth muscle actin (α-SMA) defines the phenotype of activated (myofibroblastic) hepatic stellate cells. These cells, but not quiescent stellate cells, have a high level of α-SMA and c-Myb expression, as well as increased c-Myb-binding activities to the proximal α-SMA E box. Therefore, we analyzed the role of c-Myb in α-SMA transcription and stellate cell activation. Activated primary rat stellate cells displayed a high expression of the −724 and −271 α-SMA/luciferase (LUC) chimeric genes, which contain c-Myb binding sites (−223/−216 bp). α-SMA/LUC minigenes with mutation (−219/−217 bp), truncation (−224 bp), or deletion (−191 bp) of the c-Myb binding site were not efficiently transcribed. Transfection of wild-type c-Myb into quiescent stellate cells, which do not express endogenous c-Myb, induced a ∼10-fold stimulation of −724 α-SMA/LUC expression. Conversely, expression of either a dominant-negative c-Myb basic domain mutant (Cys43 → Asp) or a c-Myb antisense RNA blocked transcription from the −724 α-SMA/LUC or −271 α-SMA/LUC in activated cells. Moreover, transfection of c- myb antisense, but not sense, RNA inhibited both expression of the endogenous α-SMA gene and stellate cell activation, whereas transfection of c- myb stimulated α-SMA expression in quiescent stellate cells. These findings suggest that c-Myb modulates the activation of stellate cells and that integrity of the redox sensor Cys43in c-Myb is required for this effect.

? Isoform of smooth muscle actin is expressed in astrocytes in vitro and in vivo

1991 ◽  
Vol 28 (4) ◽  
pp. 601-606 ◽  
Author(s):  
E. Lecain ◽  
F. Alliot ◽  
M. C. Laine ◽  
B. Calas ◽  
B. Pessac
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Actin ◽  
Muscle Actin

scholarly journals The NH2-terminal peptide of α–smooth muscle actin inhibits force generation by the myofibroblast in vitro and in vivo

2002 ◽  
Vol 157 (4) ◽  
pp. 657-663 ◽  
Author(s):  
Boris Hinz ◽  
Giulio Gabbiani ◽  
Christine Chaponnier
Keyword(s):  
Smooth Muscle ◽  
Granulation Tissue ◽  
Contractile Activity ◽  
Smooth Muscle Actin ◽  
Topical Administration ◽  
Force Generation ◽  
Muscle Actin ◽  
Actin Isoforms

Myofibroblasts are specialized fibroblasts responsible for granulation tissue contraction and the soft tissue retractions occurring during fibrocontractive diseases. The marker of fibroblast-myofibroblast modulation is the neo expression of α–smooth muscle actin (α-SMA), the actin isoform typical of vascular smooth muscle cells that has been suggested to play an important role in myofibroblast force generation. Actin isoforms differ slightly in their NH2-terminal sequences; these conserved differences suggest different functions. When the NH2-terminal sequence of α-SMA Ac-EEED is delivered to cultured myofibroblast in the form of a fusion peptide (FP) with a cell penetrating sequence, it inhibits their contractile activity; moreover, upon topical administration in vivo it inhibits the contraction of rat wound granulation tissue. The NH2-terminal peptide of α–skeletal actin has no effect on myofibroblasts, whereas the NH2-terminal peptide of β–cytoplasmic actin abolishes the immunofluorescence staining for this isoform without influencing α-SMA distribution and cell contraction. The FPs represent a new tool to better understand the specific functions of actin isoforms. Our findings support the crucial role of α-SMA in wound contraction. The α-SMA–FP will be useful for the understanding of the mechanisms of connective tissue remodeling; moreover, it furnishes the basis for a cytoskeleton-dependent preventive and/or therapeutic strategy for fibrocontractive pathological situations.

Alpha-smooth muscle actin in pathological human disc nucleus pulposus cells in vivo and in vitro

2004 ◽  
Vol 12 (4) ◽  
pp. 430-438 ◽  
Author(s):  
Dawn Hastreiter ◽  
Jeannie Chao ◽  
QI Wang ◽  
Richard M. Ozuna ◽  
Myron Spector
Keyword(s):  
Smooth Muscle ◽  
Nucleus Pulposus ◽  
Smooth Muscle Actin ◽  
Muscle Actin ◽  
Nucleus Pulposus Cells ◽  
Alpha Smooth Muscle Actin
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