scholarly journals Effects of the Regulatory Light Chain Phosphorylation of Myosin II on Mitosis and Cytokinesis of Mammalian Cells

2000 ◽  
Vol 275 (44) ◽  
pp. 34512-34520 ◽  
Author(s):  
Satoshi Komatsu ◽  
Takeo Yano ◽  
Masao Shibata ◽  
Richard A. Tuft ◽  
Mitsuo Ikebe
Keyword(s):  
Light Chain ◽  
Mammalian Cells ◽  
Myosin Ii ◽  
Regulatory Light Chain ◽  
Regulatory Light Chain Phosphorylation

scholarly journals Nonmuscle myosin IIA dynamically guides regulatory light chain phosphorylation and assembly of nonmuscle myosin IIB

2021 ◽  
Author(s):  
Kai Weissenbruch ◽  
Magdalena Fladung ◽  
Justin Grewe ◽  
Laurent Baulesch ◽  
Ulrich Sebastian Schwarz ◽  
...  
Keyword(s):  
Light Chain ◽  
Mammalian Cells ◽  
Myosin Ii ◽  
Regulatory Light Chain ◽  
Force Generation ◽  
Nonmuscle Myosin ◽  
Force Output ◽  
Nonmuscle Myosin Ii ◽  
Phosphorylation Pattern ◽  
Regulatory Light Chain Phosphorylation

Nonmuscle myosin II minifilaments have emerged as central elements for force generation and mechanosensing by mammalian cells. Each minifilament can have a different composition and activity due to the existence of the three nonmuscle myosin II isoforms A, B and C and their respective phosphorylation pattern. We have used CRISPR/Cas9-based knockout cells, quantitative image analysis and mathematical modelling to dissect the dynamic processes that control the formation and activity of heterotypic minifilaments and found a strong asymmetry between isoforms A and B. Loss of NM IIA completely abrogates regulatory light chain phosphorylation and reduces the level of assembled NM IIB. Activated NM IIB preferentially co-assembles into pre-formed NM IIA minifilaments and stabilizes the filament in a force-dependent mechanism. NM IIC is only weakly coupled to these processes. We conclude that NM IIA and B play clearly defined complementary roles during assembly of functional minifilaments. NM IIA is responsible for the formation of nascent pioneer minifilaments. NM IIB incorporates into these and acts as a clutch that limits the force output to prevent excessive NM IIA activity. Together these two isoforms form a balanced system for regulated force generation.

Telokin/KRP differentially modulates myosin II filament assembly and regulatory light chain phosphorylation in fibroblasts

BIOPHYSICS ◽  
2006 ◽  
Vol 51 (5) ◽  
pp. 764-770
Author(s):  
D. V. Serebryanaya ◽  
O. V. Shcherbakova ◽  
T. V. Dudnakova ◽  
V. P. Shirinsky ◽  
A. V. Vorotnikov
Keyword(s):  
Light Chain ◽  
Myosin Ii ◽  
Regulatory Light Chain ◽  
Filament Assembly ◽  
Regulatory Light Chain Phosphorylation

scholarly journals A fluorescent protein biosensor of myosin II regulatory light chain phosphorylation reports a gradient of phosphorylated myosin II in migrating cells.

1995 ◽  
Vol 6 (12) ◽  
pp. 1755-1768 ◽  
Author(s):  
P L Post ◽  
R L DeBiasio ◽  
D L Taylor
Keyword(s):  
Energy Transfer ◽  
Light Chain ◽  
Fluorescent Protein ◽  
Myosin Ii ◽  
Leading Edge ◽  
Living Cells ◽  
Regulatory Light Chain ◽  
Actin Binding ◽  
Transfer Ratio ◽  
Regulatory Light Chain Phosphorylation

Phosphorylation of the regulatory light chain by myosin light chain kinase (MLCK) regulates the motor activity of smooth muscle and nonmuscle myosin II. We have designed reagents to detect this phosphorylation event in living cells. A new fluorescent protein biosensor of myosin II regulatory light chain phosphorylation (FRLC-Rmyosin II) is described here. The biosensor depends upon energy transfer from fluorescein-labeled regulatory light chains to rhodamine-labeled essential and/or heavy chains. The energy transfer ratio increases by up to 26% when the regulatory light chain is phosphorylated by MLCK. The majority of the change in energy transfer is from regulatory light chain phosphorylation by MLCK (versus phosphorylation by protein kinase C). Folding/unfolding, filament assembly, and actin binding do not have a large effect on the energy transfer ratio. FRLC-Rmyosin II has been microinjected into living cells, where it incorporates into stress fibers and transverse fibers. Treatment of fibroblasts containing FRLC-Rmyosin II with the kinase inhibitor staurosporine produced a lower ratio of rhodamine/fluorescein emission, which corresponds to a lower level of myosin II regulatory light chain phosphorylation. Locomoting fibroblasts containing FRLC-Rmyosin II showed a gradient of myosin II phosphorylation that was lowest near the leading edge and highest in the tail region of these cells, which correlates with previously observed gradients of free calcium and calmodulin activation. Maximal myosin II motor force in the tail may contribute to help cells maintain their polarized shape, retract the tail as the cell moves forward, and deliver disassembled subunits to the leading edge for incorporation into new fibers.

Regulation of myosin regulatory light chain phosphorylation via cyclic GMP during chemotaxis of Dictyostelium

1994 ◽  
Vol 107 (7) ◽  
pp. 1737-1743 ◽  
Author(s):  
G. Liu ◽  
P.C. Newell
Keyword(s):  
Cyclic Amp ◽  
Light Chain ◽  
Cyclic Gmp ◽  
Myosin Ii ◽  
Regulatory Light Chain ◽  
Published Data ◽  
Myosin Regulatory Light Chain ◽  
Control Strain ◽  
Regulatory Light Chain Phosphorylation ◽  
Stimulation Of

Previous studies on the chemotactic movement of Dictyostelium have indicated a role for cyclic GMP in regulating the association of myosin II with the cytoskeleton. In this study we have examined the part played by phosphorylation of the 18 kDa myosin regulatory light chain in this event. Using streamer F mutant NP368 (which is deficient in the structural gene for cyclic GMP-specific phosphodiesterase) we find that, for the regulatory light chain kinase, the major peak of phosphorylation is delayed compared to the parental control strain XP55, occurring at 80 seconds rather than about 30 seconds in XP55. In two independently derived mutants that are unable to increase their cellular concentration of cyclic GMP (above basal levels) in response to a chemotactic stimulus of cyclic AMP (KI-10 and SA219), no increase in the phosphorylation of the light chain occurred, or movement of myosin II to the cytoskeleton. We also find a smaller peak of light chain phosphorylation that occurs within 10 seconds of cyclic AMP stimulation of the amoebae, and which is absent in the cyclic GMP-unresponsive strains. We conclude that cyclic GMP is involved in regulating light chain phosphorylation in this system. The possible significance of these findings is discussed and a model that relates these findings to published data on cytoskeletal myosin changes during chemotaxis is presented.

scholarly journals Effect of ATP and regulatory light-chain phosphorylation on the polymerization of mammalian nonmuscle myosin II

2017 ◽  
Vol 114 (32) ◽  
pp. E6516-E6525 ◽  
Author(s):  
Xiong Liu ◽  
Neil Billington ◽  
Shi Shu ◽  
Shu-Hua Yu ◽  
Grzegorz Piszczek ◽  
...  
Keyword(s):  
Light Scattering ◽  
Light Chain ◽  
Myosin Ii ◽  
Monomer Concentration ◽  
Regulatory Light Chain ◽  
Nonmuscle Myosin ◽  
Nonmuscle Myosin Ii ◽  
New Location ◽  
Regulatory Light Chain Phosphorylation

Addition of 1 mM ATP substantially reduces the light scattering of solutions of polymerized unphosphorylated nonmuscle myosin IIs (NM2s), and this is reversed by phosphorylation of the regulatory light chain (RLC). It has been proposed that these changes result from substantial depolymerization of unphosphorylated NM2 filaments to monomers upon addition of ATP, and filament repolymerization upon RLC-phosphorylation. We now show that the differences in myosin monomer concentration of RLC-unphosphorylated and -phosphorylated recombinant mammalian NM2A, NM2B, and NM2C polymerized in the presence of ATP are much too small to explain their substantial differences in light scattering. Rather, we find that the decrease in light scattering upon addition of ATP to polymerized unphosphorylated NM2s correlates with the formation of dimers, tetramers, and hexamers, in addition to monomers, an increase in length, and decrease in width of the bare zones of RLC-unphosphorylated filaments. Both effects of ATP addition are reversed by phosphorylation of the RLC. Our data also suggest that, contrary to previous models, assembly of RLC-phosphorylated NM2s at physiological ionic strength proceeds from folded monomers to folded antiparallel dimers, tetramers, and hexamers that unfold and polymerize into antiparallel filaments. This model could explain the dynamic relocalization of NM2 filaments in vivo by dephosphorylation of RLC-phosphorylated filaments, disassembly of the dephosphorylated filaments to folded monomers, dimers, and small oligomers, followed by diffusion of these species, and reassembly of filaments at the new location following rephosphorylation of the RLC.

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