[331] EXPRESSION, LOCALISATION AND ROLE OF NONMUSCLE MYOSIN II ISOFORMS IN MOUSE HEPATIC STELLATE CELLS

AbstractMigration and contraction of activated hepatic stellate cell (HSC) are essential factors for cirrhosis formation and development. It has been demonstrated that blebbistatin, a nonmuscle myosin II (NMMII) inhibitor, can inhibit the migration and contraction of HSC, whereas the main cell signaling pathway is still unknown. Mammalian target of rapamycin (mTOR) signaling pathway may be involved in many cells migration and contraction, whether NMMII and mTOR have any crosslinks draw our attention. In the currently study, we used LV-RNAi to specifically attenuate mTOR and NMMII in rat HSC. We aimed to examine the effect of mTOR LV-RNAi on the migration and contraction of HSC and explore the crosslink between mTOR cell signal and NMMII. Using real-time PCR and western blot, we found that mTOR and the downstream factors including S6K and 4EBP1 all up-regulated with the activation of HSC, mTOR and NMMII LV-RNAi was transfected into activated HSC using lipofectamine 2000. The levels of mRNA and proteins were also examined using real-time PCR and western blot respectively. The expression of mTOR can be down-regulated by NMMII LV-RNAi significantly, as well as the expression of S6K, 4EBP1, α-SMA and collagen I, but the level of AKT was up-regulated. Then we used Transwell system and collagen lattices to examine the NMMII and mTOR LV-RNAi efficiency on HSC migration and contraction, as we hypothesized, both of the LV-RNAi could inhibit HSC migration and contraction significantly. These results indicated that nonmuscle myosin II shRNA inhibit migration and contraction in rat hepatic stellate cells through the regulation of mTOR/S6K/4EBP1 signaling pathway

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Emerging Role of Nonmuscle Myosin II and Implications for NMMII Associated Deafness

Otolaryngology ◽

10.1177/0194599811415823a246 ◽

2011 ◽

Vol 145 (2_suppl) ◽

pp. P209-P210

Author(s):

Elliott Kozin ◽

Bechara Kachar ◽

Felipe Salles ◽

Robert Adelstein ◽

Xuefei Ma ◽

...

Keyword(s):

Myosin Ii ◽

Nonmuscle Myosin ◽

Nonmuscle Myosin Ii

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Second-Site Noncomplementation Identifies Genomic Regions Required for Drosophila Nonmuscle Myosin Function During Morphogenesis

Genetics ◽

10.1093/genetics/148.4.1845 ◽

1998 ◽

Vol 148 (4) ◽

pp. 1845-1863

Author(s):

Susan R Halsell ◽

Daniel P Kiehart

Keyword(s):

Cell Shape ◽

Myosin Ii ◽

Nonmuscle Myosin ◽

Genetic Screens ◽

Nonmuscle Myosin Ii ◽

Cell Shape Changes ◽

Genomic Regions ◽

Shape Changes ◽

Strong Interactors

Abstract Drosophila is an ideal metazoan model system for analyzing the role of nonmuscle myosin-II (henceforth, myosin) during development. In Drosophila, myosin function is required for cytokinesis and morphogenesis driven by cell migration and/or cell shape changes during oogenesis, embryogenesis, larval development and pupal metamorphosis. The mechanisms that regulate myosin function and the supramolecular structures into which myosin incorporates have not been systematically characterized. The genetic screens described here identify genomic regions that uncover loci that facilitate myosin function. The nonmuscle myosin heavy chain is encoded by a single locus, zipper. Contiguous chromosomal deficiencies that represent approximately 70% of the euchromatic genome were screened for genetic interactions with two recessive lethal alleles of zipper in a second-site noncomplementation assay for the malformed phenotype. Malformation in the adult leg reflects aberrations in cell shape changes driven by myosin-based contraction during leg morphogenesis. Of the 158 deficiencies tested, 47 behaved as second-site noncomplementors of zipper. Two of the deficiencies are strong interactors, 17 are intermediate and 28 are weak. Finer genetic mapping reveals that mutations in cytoplasmic tropomyosin and viking (collagen IV) behave as second-site noncomplementors of zipper during leg morphogenesis and that zipper function requires a previously uncharacterized locus, E3.10/J3.8, for leg morphogenesis and viability.

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Differential role of nonmuscle myosin II isoforms during blebbing of MCF-7 cells

Molecular Biology of the Cell ◽

10.1091/mbc.e16-07-0524 ◽

2017 ◽

Vol 28 (8) ◽

pp. 1034-1042 ◽

Cited By ~ 5

Author(s):

Sumit K. Dey ◽

Raman K. Singh ◽

Shyamtanu Chattoraj ◽

Shekhar Saha ◽

Alakesh Das ◽

...

Keyword(s):

Life Cycle ◽

Actin Filament ◽

Myosin Ii ◽

Nonmuscle Myosin ◽

Nonmuscle Myosin Ii ◽

Different Types ◽

Membrane Protrusions ◽

Bleb Formation ◽

Mcf 7

Bleb formation has been correlated with nonmuscle myosin II (NM-II) activity. Whether three isoforms of NM-II (NM-IIA, -IIB and -IIC) have the same or differential roles in bleb formation is not well understood. Here we report that ectopically expressed, GFP-tagged NM-II isoforms exhibit different types of membrane protrusions, such as multiple blebs, lamellipodia, combinations of both, or absence of any such protrusions in MCF-7 cells. Quantification suggests that 50% of NM-IIA-GFP–, 29% of NM-IIB-GFP–, and 19% of NM-IIC1-GFP–expressing MCF-7 cells show multiple bleb formation, compared with 36% of cells expressing GFP alone. Of interest, NM-IIB has an almost 50% lower rate of dissociation from actin filament than NM-IIA and –IIC1 as determined by FRET analysis both at cell and bleb cortices. We induced bleb formation by disruption of the cortex and found that all three NM-II-GFP isoforms can reappear and form filaments but to different degrees in the growing bleb. NM-IIB-GFP can form filaments in blebs in 41% of NM-IIB-GFP–expressing cells, whereas filaments form in only 12 and 3% of cells expressing NM-IIA-GFP and NM-IIC1-GFP, respectively. These studies suggest that NM-II isoforms have differential roles in the bleb life cycle.

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Carboxyl-terminal-dependent recruitment of nonmuscle myosin II to megakaryocyte contractile ring during polyploidization

Blood ◽

10.1182/blood-2014-06-584995 ◽

2014 ◽

Vol 124 (16) ◽

pp. 2564-2568 ◽

Cited By ~ 7

Author(s):

Idinath Badirou ◽

Jiajia Pan ◽

Céline Legrand ◽

Aibing Wang ◽

Larissa Lordier ◽

...

Keyword(s):

Myosin Ii ◽

Specific Role ◽

Nonmuscle Myosin ◽

Contractile Ring ◽

Terminal Domain ◽

Nonmuscle Myosin Ii ◽

Key Points ◽

Carboxyl Terminal

Key Points C-terminal domain determines myosin II localization to the MK contractile ring and the specific role of NMII-B in MK polyploidization.

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Concerted actions of distinct nonmuscle myosin II isoforms drive intracellular membrane remodeling in live animals

The Journal of Cell Biology ◽

10.1083/jcb.201612126 ◽

2017 ◽

Vol 216 (7) ◽

pp. 1925-1936 ◽

Cited By ~ 29

Author(s):

Oleg Milberg ◽

Akiko Shitara ◽

Seham Ebrahim ◽

Andrius Masedunskas ◽

Muhibullah Tora ◽

...

Keyword(s):

Molecular Mechanisms ◽

Secretory Granules ◽

Myosin Ii ◽

Membrane Remodeling ◽

Nonmuscle Myosin ◽

Nonmuscle Myosin Ii ◽

Mammalian Tissues ◽

Actomyosin Cytoskeleton

Membrane remodeling plays a fundamental role during a variety of biological events. However, the dynamics and the molecular mechanisms regulating this process within cells in mammalian tissues in situ remain largely unknown. In this study, we use intravital subcellular microscopy in live mice to study the role of the actomyosin cytoskeleton in driving the remodeling of membranes of large secretory granules, which are integrated into the plasma membrane during regulated exocytosis. We show that two isoforms of nonmuscle myosin II, NMIIA and NMIIB, control distinct steps of the integration process. Furthermore, we find that F-actin is not essential for the recruitment of NMII to the secretory granules but plays a key role in the assembly and activation of NMII into contractile filaments. Our data support a dual role for the actomyosin cytoskeleton in providing the mechanical forces required to remodel the lipid bilayer and serving as a scaffold to recruit key regulatory molecules.

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Control of nuclear centration in the C. elegans zygote by receptor-independent Gα signaling and myosin II

The Journal of Cell Biology ◽

10.1083/jcb.200703159 ◽

2007 ◽

Vol 178 (7) ◽

pp. 1177-1191 ◽

Cited By ~ 29

Author(s):

Morgan B. Goulding ◽

Julie C. Canman ◽

Eric N. Senning ◽

Andrew H. Marcus ◽

Bruce Bowerman

Keyword(s):

Mitotic Spindle ◽

Myosin Ii ◽

Nonmuscle Myosin ◽

Wild Type ◽

Spindle Positioning ◽

C Elegans ◽

Nonmuscle Myosin Ii ◽

Pulling Forces ◽

Actomyosin Contraction

Mitotic spindle positioning in the Caenorhabditis elegans zygote involves microtubule-dependent pulling forces applied to centrosomes. In this study, we investigate the role of actomyosin in centration, the movement of the nucleus–centrosome complex (NCC) to the cell center. We find that the rate of wild-type centration depends equally on the nonmuscle myosin II NMY-2 and the Gα proteins GOA-1/GPA-16. In centration- defective let-99(−) mutant zygotes, GOA-1/GPA-16 and NMY-2 act abnormally to oppose centration. This suggests that LET-99 determines the direction of a force on the NCC that is promoted by Gα signaling and actomyosin. During wild-type centration, NMY-2–GFP aggregates anterior to the NCC tend to move further anterior, suggesting that actomyosin contraction could pull the NCC. In GOA-1/GPA-16–depleted zygotes, NMY-2 aggregate displacement is reduced and largely randomized, whereas in a let-99(−) mutant, NMY-2 aggregates tend to make large posterior displacements. These results suggest that Gα signaling and LET-99 control centration by regulating polarized actomyosin contraction.

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