scholarly journals Non-muscle myosin II induces disassembly of actin stress fibres independently of myosin light chain dephosphorylation

2011 ◽  
Vol 1 (5) ◽  
pp. 754-766 ◽  
Author(s):  
Tsubasa S. Matsui ◽  
Roland Kaunas ◽  
Makoto Kanzaki ◽  
Masaaki Sato ◽  
Shinji Deguchi
Keyword(s):  
Light Chain ◽  
Actin Filaments ◽  
Myosin Light Chain ◽  
Myosin Ii ◽  
Physiological Level ◽  
Cell Shortening ◽  
Applied Forces ◽  
Selective Disassembly ◽  
The Individual ◽  
Muscle Myosin

Dynamic remodelling of actin stress fibres (SFs) allows non-muscle cells to adapt to applied forces such as uniaxial cell shortening. However, the mechanism underlying rapid and selective disassembly of SFs oriented in the direction of shortening remains to be elucidated. Here, we investigated how myosin crossbridge cycling induced by MgATP is associated with SF disassembly. Moderate concentrations of MgATP, or [MgATP], induced SF contraction. Meanwhile, at [MgATP] slightly higher than the physiological level, periodic actin patterns emerged along the length of SFs and dispersed within seconds. The actin fragments were diverse in length, but comparable to those in characteristic sarcomeric units of SFs. These results suggest that MgATP-bound non-muscle myosin II dissociates from the individual actin filaments that constitute the sarcomeric units, resulting in unbundling-induced disassembly rather than end-to-end actin depolymerization. This rapid SF disassembly occurred independent of dephosphorylation of myosin light chain. In terms of effects on actin–myosin interactions, a rise in [MgATP] is functionally equivalent to a temporal decrease in the total number of actin–myosin crossbridges. Actin–myosin crossbridges are known to be reduced by an assisting load on myosin. Thus, the present study suggests that reducing the number of actin–myosin crossbridges promotes rapid and orientation-dependent disassembly of SFs after cell shortening.

The E1841K Mutation in MYH-9 of a Patient with May-Hegglin Anomaly Inhibits the Disassembly of Non-Muscle Myosin IIA (MYH-9) Responsible for the Phenotype of the Disease.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 736-736 ◽  
Author(s):  
Koji Miyazaki ◽  
Satoshi Komatsu ◽  
Mariko Watanabe ◽  
Naoya Nakadate ◽  
Mitsuo Ikebe ◽  
...  
Keyword(s):  
Light Chain ◽  
Actin Filaments ◽  
Inclusion Bodies ◽  
Myosin Light Chain ◽  
Immunofluorescent Staining ◽  
Molecular Characteristics ◽  
Wild Type ◽  
Hel Cells ◽  
Myosin Iia ◽  
Muscle Myosin

Abstract It has been demonstrated that MYH-9 (non-muscle myosin IIA) is responsible for the hereditary macrothrombocytopenia, such as May-Hegglin Anomaly (MHA), Fechtner syndrome (FS) and Sebastian syndrome (SS). We identified the E1841K mutation of MYH-9 gene of a patient with May-Hegglin Anomaly. Immunofluorescent staining of her peripheral blood smear samples revealed that non-muscle myosin IIA and actin filaments were co-localized at the Döhle-like inclusion bodies of neutrophils. To investigate the mechanism by which the E1841K mutation causes the phenotype of MHA, we first expressed GFP-tagged wild type and E1841K mutant MYH-9 cDNA in NIH3T3 cells. The mutant was able to form filaments and some inclusion bodies such as Döhle-like bodies, although it seemed to make no influences on the shape of the fibroblasts. Next we expressed the GFP-tagged wild and E1841K mutant MYH-9 in HEL cells and induced differentiation with TPA. HEL cells expressing the E1841K mutant failed in full differentiation. They could not produce the proplatelet-like projections as the cells overexpressing wild type of MYH-9 did. These results demonstrate that overexpression of this mutant can induce some phenotype similar to MHA. To clarify what molecular characteristics of the mutant myosin can cause the MHA phenotype, we expressed the recombinant wild and mutant proteins of non-muscle myosin IIA using Baculo-virus system. The mutant myosin failed to dissolve even in high ionic strength, suggesting this mutant can assemble in cytoplasm even under the condition, in which wild type myosin changes the conformation and exchanges dynamically assembly to disassembly. Next we induced myosin filaments in HEL cells by over-expressing the mutant of myosin light chain (DD mutant), which mimics the double-phosphorylated form. The DD mutant of myosin light chain also inhibited the proplatelet-like projections. Moreover silencing of MYH-9 gene with siRNA could have no inhibitory effects on the differentiation of HEL cells, producing rather more proplatelet-like projections than the control. These results indicated that filament formation of myosin is not critical for proplatelet-like projections, but disassembly of myosin is rather essential. Collectively, the E1841K mutant inhibits the disassembly of myosin to prevent the proplatelet-like formation of HEL cells, and the assembled myosin forms the Döhle-like inclusion bodies probably with actin filaments.

scholarly journals Non-muscle Myosin II and Myosin Light Chain Kinase Are Downstream Targets for Vasopressin Signaling in the Renal Collecting Duct

2004 ◽  
Vol 279 (47) ◽  
pp. 49026-49035 ◽  
Author(s):  
Chung-Lin Chou ◽  
Birgitte M. Christensen ◽  
Sebastian Frische ◽  
Henrik Vorum ◽  
Ravi A. Desai ◽  
...  
Keyword(s):  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Collecting Duct ◽  
Myosin Ii ◽  
Downstream Targets ◽  
Renal Collecting Duct ◽  
Muscle Myosin

scholarly journals An Alternatively Spliced Isoform of Non-muscle Myosin II-C Is Not Regulated by Myosin Light Chain Phosphorylation

2009 ◽  
Vol 284 (17) ◽  
pp. 11563-11571 ◽  
Author(s):  
Siddhartha S. Jana ◽  
Kye-Young Kim ◽  
Jian Mao ◽  
Sachiyo Kawamoto ◽  
James R. Sellers ◽  
...  
Keyword(s):  
Light Chain ◽  
Myosin Light Chain ◽  
Myosin Ii ◽  
Myosin Light Chain Phosphorylation ◽  
Alternatively Spliced ◽  
Muscle Myosin

scholarly journals Distinct Roles of Smooth Muscle and Non-muscle Myosin Light Chain-Mediated Smooth Muscle Contraction

2020 ◽  
Vol 11 ◽  
Author(s):  
Jie Sun ◽  
Yan-Ning Qiao ◽  
Tao Tao ◽  
Wei Zhao ◽  
Li-Sha Wei ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Initial Phase ◽  
Myosin Light Chain ◽  
Myosin Ii ◽  
Smooth Muscle Contraction ◽  
Myosin Regulatory Light Chain ◽  
Gene Encoding ◽  
Muscle Myosin

Both smooth muscle (SM) and non-muscle (NM) myosin II are expressed in hollow organs such as the bladder and uterus, but their respective roles in contraction and corresponding physiological functions remain to be determined. In this report, we assessed their roles by analyzing mice deficient of Myl9, a gene encoding the SM myosin regulatory light chain (SM RLC). We find that global Myl9-deficient bladders contracted with an apparent sustained phase, despite no initial phase. This sustained contraction was mediated by NM myosin RLC (NM RLC) phosphorylation by myosin light chain kinase (MLCK). NM myosin II was expressed abundantly in the uterus and young mice bladders, of which the force was accordingly sensitive to NM myosin inhibition. Our findings reveal distinct roles of SM RLC and NM RLC in SM contraction.

scholarly journals Myosin light chain kinase steady-state kinetics: comparison of smooth muscle myosin II and nonmuscle myosin IIB as substrates

2016 ◽  
Vol 34 (7) ◽  
pp. 469-474 ◽  
Author(s):  
Diego B. Alcala ◽  
Brian D. Haldeman ◽  
Richard K. Brizendine ◽  
Agata K. Krenc ◽  
Josh E. Baker ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Steady State ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Myosin Ii ◽  
Smooth Muscle Myosin ◽  
Nonmuscle Myosin ◽  
Steady State Kinetics ◽  
Muscle Myosin
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