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

2007 ◽  
Vol 178 (7) ◽  
pp. 1177-1191 ◽  
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.

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

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

scholarly journals Ablation of Nonmuscle Myosin II-B and II-C Reveals a Role for Nonmuscle Myosin II in Cardiac Myocyte Karyokinesis

2010 ◽  
Vol 21 (22) ◽  
pp. 3952-3962 ◽  
Author(s):  
Xuefei Ma ◽  
Siddhartha S. Jana ◽  
Mary Anne Conti ◽  
Sachiyo Kawamoto ◽  
William C. Claycomb ◽  
...  
Keyword(s):  
Cardiac Myocyte ◽  
Interstitial Fibrosis ◽  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Wild Type ◽  
Intercalated Discs ◽  
Nonmuscle Myosin Ii ◽  
Chromatid Segregation ◽  
Cardiac Myocyte Hypertrophy ◽  
Interfering Rna

Ablation of nonmuscle myosin (NM) II-A or NM II-B results in mouse embryonic lethality. Here, we report the results of ablating NM II-C as well as NM II-C/II-B together in mice. NM II-C ablated mice survive to adulthood and show no obvious defects compared with wild-type littermates. However, ablation of NM II-C in mice expressing only 12% of wild-type amounts of NM II-B results in a marked increase in cardiac myocyte hypertrophy compared with the NM II-B hypomorphic mice alone. In addition, these hearts develop interstitial fibrosis associated with diffuse N-cadherin and β-catenin localization at the intercalated discs, where both NM II-B and II-C are normally concentrated. When both NM II-C and II-B are ablated the B−C−/B−C− cardiac myocytes show major defects in karyokinesis. More than 90% of B−C−/B−C− myocytes demonstrate defects in chromatid segregation and mitotic spindle formation accompanied by increased stability of microtubules and abnormal formation of multiple centrosomes. This requirement for NM II in karyokinesis is further demonstrated in the HL-1 cell line derived from mouse atrial myocytes, by using small interfering RNA knockdown of NM II or treatment with the myosin inhibitor blebbistatin. Our study shows that NM II is involved in regulating cardiac myocyte karyokinesis by affecting microtubule dynamics.

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

Genetics ◽  
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.

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

2017 ◽  
Vol 28 (8) ◽  
pp. 1034-1042 ◽  
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.

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

Blood ◽  
2014 ◽  
Vol 124 (16) ◽  
pp. 2564-2568 ◽  
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.

scholarly journals PIG-1 MELK-dependent phosphorylation of nonmuscle myosin II promotes apoptosis through CES-1 Snail partitioning

2020 ◽  
Author(s):  
Hai Wei ◽  
Eric J. Lambie ◽  
Daniel S. Osório ◽  
Ana X. Carvalho ◽  
Barbara Conradt
Keyword(s):  
Myosin Ii ◽  
Critical Role ◽  
Transcriptional Repressor ◽  
Nonmuscle Myosin ◽  
C Elegans ◽  
Apoptotic Gene ◽  
Nonmuscle Myosin Ii ◽  
Snail Family ◽  
Regulatory Loop ◽  
Dependent Pathway

AbstractThe mechanism(s) through which mammalian kinase MELK promotes tumorigenesis is not understood. We find that the C. elegans orthologue of MELK, PIG-1, promotes apoptosis by partitioning an anti-apoptotic factor. The C. elegans NSM neuroblast divides to produce a larger cell that differentiates into a neuron and a smaller cell that dies. We find that in this context, PIG-1 is required for partitioning of CES-1 Snail, a transcriptional repressor of the pro-apoptotic gene egl-1 BH3-only. pig-1 MELK is controlled by both a ces-1 Snail- and par-4 LKB1-dependent pathway, and may act through phosphorylation and cortical enrichment of nonmuscle myosin II prior to neuroblast division. We propose that pig-1 MELK-induced local contractility of the actomyosin network plays a conserved role in the acquisition of the apoptotic fate. Our work also uncovers an auto-regulatory loop through which ces-1 Snail controls its own activity through the formation of a gradient of CES-1 Snail protein.Significance StatementApoptosis is critical for the elimination of ‘unwanted’ cells. What distinguishes wanted from unwanted cells in developing animals is poorly understood. We report that in the C. elegans NSM neuroblast lineage, the level of CES-1, a Snail-family member and transcriptional repressor of the pro-apoptotic gene egl-1, contributes to this process. In addition, we demonstrate that C. elegans PIG-1, the orthologue of mammalian proto-oncoprotein MELK, plays a critical role in controlling CES-1Snail levels. Specifically, during NSM neuroblast division, PIG-1MELK controls partitioning of CES-1Snail into one but not the other daughter cell thereby promoting the making of one wanted and one unwanted cell. Furthermore, we present evidence that PIG-1MELK acts prior to NSM neuroblast division by locally activating the actomyosin network.

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

2007 ◽  
Vol 46 ◽  
pp. S130 ◽  
Author(s):  
Z.A. Liu ◽  
H. Reynaert ◽  
E. Van Rossen ◽  
B. Schroyen ◽  
L. van Grunsven ◽  
...  
Keyword(s):  
Hepatic Stellate Cells ◽  
Myosin Ii ◽  
Stellate Cells ◽  
Nonmuscle Myosin ◽  
Nonmuscle Myosin Ii

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

2017 ◽  
Vol 216 (7) ◽  
pp. 1925-1936 ◽  
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.

scholarly journals Protein Kinase Cγ Regulates Myosin IIB Phosphorylation, Cellular Localization, and Filament Assembly

2006 ◽  
Vol 17 (3) ◽  
pp. 1364-1374 ◽  
Author(s):  
Michael Rosenberg ◽  
Shoshana Ravid
Keyword(s):  
Cellular Localization ◽  
Myosin Ii ◽  
Dominant Negative ◽  
Phosphorylation Sites ◽  
Nonmuscle Myosin ◽  
Wild Type ◽  
Filament Assembly ◽  
Nonmuscle Myosin Ii ◽  
Pkc Isoforms ◽  
Epidermal Growth

Nonmuscle myosin II is an important component of the cytoskeleton, playing a major role in cell motility and chemotaxis. We have previously demonstrated that, on stimulation with epidermal growth factor (EGF), nonmuscle myosin heavy chain II-B (NMHC-IIB) undergoes a transient phosphorylation correlating with its cellular localization. We also showed that members of the PKC family are involved in this phosphorylation. Here we demonstrate that of the two conventional PKC isoforms expressed by prostate cancer cells, PKCβII and PKCγ, PKCγ directly phosphorylates NMHC-IIB. Overexpression of wild-type and kinase dead dominant negative PKCγ result in both altered NMHC-IIB phosphorylation and subcellular localization. We have also mapped the phosphorylation sites of PKCγ on NMHC-IIB. Conversion of the PKCγ phosphorylation sites to alanine residues, reduces the EGF-dependent NMHC-IIB phosphorylation. Aspartate substitution of these sites reduces NMHC-IIB localization into cytoskeleton. These results indicate that PKCγ regulates NMHC-IIB phosphorylation and cellular localization in response to EGF stimulation.

scholarly journals Optogenetic dissection of mitotic spindle positioning in vivo

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Lars-Eric Fielmich ◽  
Ruben Schmidt ◽  
Daniel J Dickinson ◽  
Bob Goldstein ◽  
Anna Akhmanova ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Membrane Anchor ◽  
Spindle Positioning ◽  
C Elegans ◽  
Cell Cleavage ◽  
Evolutionarily Conserved ◽  
Pulling Forces ◽  
Endogenous Proteins ◽  
Pulling Force

The position of the mitotic spindle determines the plane of cell cleavage, and thereby daughter cell location, size, and content. Spindle positioning is driven by dynein-mediated pulling forces exerted on astral microtubules, which requires an evolutionarily conserved complex of Gα∙GDP, GPR-1/2Pins/LGN, and LIN-5Mud/NuMA proteins. To examine individual functions of the complex components, we developed a genetic strategy for light-controlled localization of endogenous proteins in C. elegans embryos. By replacing Gα and GPR-1/2 with a light-inducible membrane anchor, we demonstrate that Gα∙GDP, Gα∙GTP, and GPR-1/2 are not required for pulling-force generation. In the absence of Gα and GPR-1/2, cortical recruitment of LIN-5, but not dynein itself, induced high pulling forces. The light-controlled localization of LIN-5 overruled normal cell-cycle and polarity regulation and provided experimental control over the spindle and cell-cleavage plane. Our results define Gα∙GDP–GPR-1/2Pins/LGN as a regulatable membrane anchor, and LIN-5Mud/NuMA as a potent activator of dynein-dependent spindle-positioning forces.

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