MARCKS actin-binding capacity mediates actin filament assembly during mitosis in human hepatic stellate cells

2012 ◽  
Vol 303 (4) ◽  
pp. C357-C367 ◽  
Author(s):  
Krista Rombouts ◽  
Tommaso Mello ◽  
Francesco Liotta ◽  
Andrea Galli ◽  
Alessandra Caligiuri ◽  
...  

Cross-linking between the actin cytoskeleton and plasma membrane actin-binding proteins is a key interaction responsible for the mechanical properties of the mitotic cell. Little is known about the identity, the localization, and the function of actin filament-binding proteins during mitosis in human hepatic stellate cells (hHSC). The aim of the present study was to identify and analyze the cross talk between actin and myristoylated alanine-rich kinase C substrate (MARCKS), an important PKC substrate and actin filament-binding protein, during mitosis in primary hHSC. Confocal analysis and chromosomal fraction analysis of mitotic hHSC demonstrated that phosphorylated (P)-MARCKS displays distinct phase-dependent localizations, accumulates at the perichromosomal layer, and is a centrosomal protein belonging to the chromosomal cytosolic fraction. Aurora B kinase (AUBK), an important mitotic regulator, β-actin, and P-MARCKS concentrate at the cytokinetic midbody during cleavage furrow formation. This localization is critical since MARCKS-depletion in hHSC is characterized by a significant loss in cytosolic actin filaments and cortical β-actin that induces cell cycle inhibition and dislocation of AUBK. A depletion of AUBK in hHSC affects cell cycle, resulting in multinucleation. Quantitative live cell imaging demonstrates that the actin filament-binding capacity of MARCKS is key to regulate mitosis since the cell cycle inhibitory effect in MARCKS-depleted cells caused abnormal cell morphology and an aberrant cytokinesis, resulting in a significant increase in cell cycle time. These findings implicate that MARCKS, an important PKC substrate, is essential for proper cytokinesis and that MARCKS and its partner actin are key mitotic regulators during cell cycle in hHSC.

2016 ◽  
Vol 423 (1-2) ◽  
pp. 9-20 ◽  
Author(s):  
Yu Huang ◽  
Di Huang ◽  
Jiefeng Weng ◽  
Shuai Zhang ◽  
Qiang Zhang ◽  
...  

2018 ◽  
Vol 48 (3) ◽  
pp. 1215-1229 ◽  
Author(s):  
Sihyung Wang ◽  
Youngmi Jung ◽  
Jeongeun Hyun ◽  
Matthew Friedersdorf ◽  
Seh-Hoon Oh ◽  
...  

Background/Aims: Myofibroblasts (MF) derived from quiescent nonfibrogenic hepatic stellate cells (HSC) are the major sources of fibrous matrix in cirrhosis. Because many factors interact to regulate expansion and regression of MF-HSC populations, efforts to prevent cirrhosis by targeting any one factor have had limited success, motivating research to identify mechanisms that integrate these diverse inputs. As key components of RNA regulons, RNA binding proteins (RBPs) may fulfill this function by orchestrating changes in the expression of multiple genes that must be coordinately regulated to affect the complex phenotypic modifications required for HSC transdifferentiation. Methods: We profiled the transcriptomes of quiescent and MF-HSC to identify RBPs that were differentially-expressed during HSC transdifferentiation, manipulated the expression of the most significantly induced RBP, insulin like growth factor 2 binding protein 3 (Igf2bp3), and evaluated transcriptomic and phenotypic effects. Results: Depleting Igf2bp3 changed the expression of thousands of HSC genes, including multiple targets of TGF-β signaling, and caused HSCs to reacquire a less proliferative, less myofibroblastic phenotype. RNA immunoprecipitation assays demonstrated that some of these effects were mediated by direct physical interactions between Igf2bp3 and mRNAs that control proliferative activity and mesenchymal traits. Inhibiting TGF-β receptor-1 signaling revealed a microRNA-dependent mechanism that induces Igf2bp3. Conclusions: The aggregate results indicate that HSC transdifferentiation is ultimately dictated by Igf2bp3-dependent RNA regulons and thus, can be controlled simply by manipulating Igf2bp3.


2020 ◽  
Vol 21 (9) ◽  
pp. 3267
Author(s):  
Anna Hübbers ◽  
Julia Hennings ◽  
Daniela Lambertz ◽  
Ute Haas ◽  
Christian Trautwein ◽  
...  

Liver fibrosis is a wound healing process in response to chronic liver injury, which is characterized by the accumulation of extracellular collagen produced by Hepatic Stellate Cells (HSCs). This process involves cell cycle re-entry and proliferation of normally quiescent HSCs controlled by cyclins and associated cyclin-dependent kinases (Cdks). Cdk2 mediates the entry and progression through S-phase in complex with E-and A-type cyclins. We have demonstrated that cyclin E1 is essential for liver fibrogenesis in mice, but it is not known if this is dependent on Cdk2 or related Cdks. Here, we aimed to evaluate the benefit of the pan-Cdk inhibitor CR8 for treatment of liver fibrosis in vitro. CR8-treatment reduced proliferation and survival in immortalized HSC lines and in addition attenuated pro-fibrotic properties in primary murine HSCs. Importantly, primary murine hepatocytes were much more tolerant against the cytotoxic and anti-proliferative effects of CR8. We identified CR8 dosages mediating anti-fibrotic effects in primary HSCs without affecting cell cycle activity and survival in primary hepatocytes. In conclusion, the pharmacological pan-Cdk inhibitor CR8 restricts the pro-fibrotic properties of HSCs, while preserving proliferation and viability of hepatocytes at least in vitro. Therefore, CR8 and related drugs might be beneficial for the treatment of liver fibrosis.


2010 ◽  
Vol 52 ◽  
pp. S374-S375 ◽  
Author(s):  
Y.A. Nevzorova ◽  
J.M. Bangen ◽  
N. Gassler ◽  
U. Haas ◽  
R. Weiskirchen ◽  
...  

2017 ◽  
Vol 95 (6) ◽  
pp. 628-633 ◽  
Author(s):  
Liang Wang ◽  
Guang Bai ◽  
Fei Chen

Bone marrow mesenchymal stem cells (BMSCs) have considerable therapeutic potential for the treatment of end-stage liver disease. Previous studies have demonstrated that BMSCs secrete growth factors and cytokines that inactivate hepatic stellate cells (HSCs), which inhibited the progression of hepatic fibrosis. The aim of this study was to determine the mechanism by which BMSCs suppress the function of HSCs in fibrosis. Our results showed that co-culture of BMSCs and HSCs induced cell cycle arrest at the G10/G1 phase and cell apoptosis of HSCs, which finally inhibited the cell proliferation of HSCs. Consistent with the cell cycle arrest, co-culture of BMSCs and HSCs increased the abundance of the cell cycle protein p27. Mechanistically, we further uncovered that following the co-culture with BMSCs, the expression level of the E3 ligase S-phase kinase-associated protein 2 (SKP2) that is responsible for the ubiquitination of p27 was decreased, which attenuated the ubiquitination of p27 and increased the stability of p27 in HSCs. Collectively, our results indicated the potential involvement of the SKP2–p27 axis for the inhibitory effect of BSMCs on the cell proliferation of HSCs.


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