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 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.

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 Multiple Regulatory Steps Control Mammalian Nonmuscle Myosin II Assembly in Live Cells

2009 ◽  
Vol 20 (1) ◽  
pp. 338-347 ◽  
Author(s):  
Mark T. Breckenridge ◽  
Natalya G. Dulyaninova ◽  
Thomas T. Egelhoff
Keyword(s):  
Conformational Change ◽  
Mammalian Cells ◽  
Myosin Ii ◽  
Phosphorylation Site ◽  
Leading Edge ◽  
Live Cells ◽  
Nonmuscle Myosin ◽  
Related Disorder ◽  
Filament Assembly ◽  
Nonmuscle Myosin Ii

To better understand the mechanism controlling nonmuscle myosin II (NM-II) assembly in mammalian cells, mutant NM-IIA constructs were created to allow tests in live cells of two widely studied models for filament assembly control. A GFP-NM-IIA construct lacking the RLC binding domain (ΔIQ2) destabilizes the 10S sequestered monomer state and results in a severe defect in recycling monomers during spreading, and from the posterior to the leading edge during polarized migration. A GFP-NM-IIA construct lacking the nonhelical tailpiece (Δtailpiece) is competent for leading edge assembly, but overassembles, suggesting defects in disassembly from lamellae subsequent to initial recruitment. The Δtailpiece phenotype was recapitulated by a GFP-NM-IIA construct carrying a mutation in a mapped tailpiece phosphorylation site (S1943A), validating the importance of the tailpiece and tailpiece phosphorylation in normal lamellar myosin II assembly control. These results demonstrate that both the 6S/10S conformational change and the tailpiece contribute to the localization and assembly of myosin II in mammalian cells. This work furthermore offers cellular insights that help explain platelet and leukocyte defects associated with R1933-stop alleles of patients afflicted with human MYH9-related disorder.

Sign in / Sign up

Export Citation Format

Share Document