Expression, localisation and role of nonmuscle myosin II isoforms in mouse hepatic stellate cells

Zhenan Liu, H. Reynaert, Elke Van Rossen, Ben Schroyen, Leo A Van Grunsven, Albert Geerts, M. Colombo (Redacteur)

Onderzoeksoutput: Conference paper


Background: Activated hepatic stellate cells have contractile properties which are mediated by myosin TI.
Aims: To investigate the expression, localization and role of nonmuscle myosin TI isoforms in mouse hepatic stellate cells (mHSCs) during activation.
Methods: Nonmuscle myosin heavy chain (NMHC) isoform expression and localization were examined by QRT-PCR, Western blot, immunofluorescence, immunohistochemistry and confocal microscopy in cultured mHSCs and in normal and cirrhotic mouse liver. Blebbistatin, a specific nonmuscle myosin TI inhibitor, was used to investigate the role of NMHC in mHSCs contraction, adhesion and wound healing. The differential localization and the role of NMHC TTA and TTB during 'wound healing' were further confirmed by isoform specific siRNA gene silencing.
Results: NMHC isoform mRNA (MYHO, MYHlO, MYH14) and protein (NMHC IIA, NMHC 11s) were expressed in cultured mHSCs. NMHC I1 mRNA (MYHP, 10, 14) were expressed in decreasing amount, at the protein level, NMHC 11A and 11B were demonstrable by western blotting. During activation of mHSCs, NMHC 11A mRNA and protein levels were constant, whereas NMHC TTB was upregulated. NMHC TTA was located in subcortical area of quiescent mHSCs and colocalized with a-SMA to form stress tibers in activated mHSCs. Knockdown of NMHC TTA by siRNA decreased stress tibers but not lamellipodia. NMHC TTB was located in cytoplasmatic processes of quiescent mHSCs and in lamellipodia and cytoplasm of activated mHSCs. Knockdown NMHC TTB by siRNA inhibited the formation of lamillipodia but not stress tibers. Inhibition of nonmuscle myosin 11 by blebbistatin decreased the myosin-actin containing stress fibers in mHSCs, blocked the ET-1-induced contraction of activated mHSCs, decreased cells adhesion to collagen, but increased migration during wound healing. Knocking down NMHC TTB impaired 'wound' induced migration, knocking down NMHC TTA had the opposite effect, i.e. migration in the wound healing assay increased.
Conclusions: NMHC 11A and 11B are differentially expressed and localized in mHSC, they play distinct and complementary roles: NMHC TTA is critical in contraction and the formation of focal adhesions, whereas NMHC TTB contributes to cell spreading and migration.
Originele taal-2English
Pagina's (van-tot)130-130
Aantal pagina's1
TijdschriftJournal of Hepatology
StatusPublished - 2007
EvenementUnknown - Stockholm, Sweden
Duur: 21 sep 200925 sep 2009

Bibliografische nota

M. Colombo


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