Ca2+ Sensitivity of Smooth Muscle and Nonmuscle Myosin II: Modulated by G Proteins, Kinases, and Myosin Phosphatase

2003 ◽  
Vol 83 (4) ◽  
pp. 1325-1358 ◽  
Author(s):  
ANDREW P. SOMLYO ◽  
AVRIL V. SOMLYO
Keyword(s):  
Smooth Muscle ◽  
G Proteins ◽  
Cancer Progression ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Myosin Phosphatase ◽  
Lim Kinase ◽  
Nonmuscle Myosin Ii

Somlyo, Andrew P., and Avril V. Somlyo. Ca2+ Sensitivity of Smooth Muscle and Nonmuscle Myosin II: Modulated by G Proteins, Kinases, and Myosin Phosphatase. Physiol Rev 83: 1325-1358, 2003; 10.1152/physrev.00023.2003.— Ca2+ sensitivity of smooth muscle and nonmuscle myosin II reflects the ratio of activities of myosin light-chain kinase (MLCK) to myosin light-chain phosphatase (MLCP) and is a major, regulated determinant of numerous cellular processes. We conclude that the majority of phenotypes attributed to the monomeric G protein RhoA and mediated by its effector, Rho-kinase (ROK), reflect Ca2+ sensitization: inhibition of myosin II dephosphorylation in the presence of basal (Ca2+ dependent or independent) or increased MLCK activity. We outline the pathway from receptors through trimeric G proteins (Gαq, Gα12, Gα13) to activation, by guanine nucleotide exchange factors (GEFs), from GDP · RhoA · GDI to GTP · RhoA and hence to ROK through a mechanism involving association of GEF, RhoA, and ROK in multimolecular complexes at the lipid cell membrane. Specific domains of GEFs interact with trimeric G proteins, and some GEFs are activated by Tyr kinases whose inhibition can inhibit Rho signaling. Inhibition of MLCP, directly by ROK or by phosphorylation of the phosphatase inhibitor CPI-17, increases phosphorylation of the myosin II regulatory light chain and thus the activity of smooth muscle and nonmuscle actomyosin ATPase and motility. We summarize relevant effects of p21-activated kinase, LIM-kinase, and focal adhesion kinase. Mechanisms of Ca2+ desensitization are outlined with emphasis on the antagonism between cGMP-activated kinase and the RhoA/ROK pathway. We suggest that the RhoA/ROK pathway is constitutively active in a number of organs under physiological conditions; its aberrations play major roles in several disease states, particularly impacting on Ca2+ sensitization of smooth muscle in hypertension and possibly asthma and on cancer neoangiogenesis and cancer progression. It is a potentially important therapeutic target and a subject for translational research.

scholarly journals Anillin Binds Nonmuscle Myosin II and Regulates the Contractile Ring

2005 ◽  
Vol 16 (1) ◽  
pp. 193-201 ◽  
Author(s):  
Aaron F. Straight ◽  
Christine M. Field ◽  
Timothy J. Mitchison
Keyword(s):  
Light Chain ◽  
Myosin Light Chain ◽  
Cultured Cells ◽  
Contractile Activity ◽  
Myosin Ii ◽  
Human Cells ◽  
Myosin Light Chain Phosphorylation ◽  
Nonmuscle Myosin ◽  
Contractile Ring ◽  
Nonmuscle Myosin Ii

We demonstrate that the contractile ring protein anillin interacts directly with nonmuscle myosin II and that this interaction is regulated by myosin light chain phosphorylation. We show that despite their interaction, anillin and myosin II are independently targeted to the contractile ring. Depletion of anillin in Drosophila or human cultured cells results in cytokinesis failure. Human cells depleted for anillin fail to properly regulate contraction by myosin II late in cytokinesis and fail in abscission. We propose a role for anillin in spatially regulating the contractile activity of myosin II during cytokinesis.

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

scholarly journals A Novel Regulatory Mechanism of Myosin Light Chain Phosphorylation via Binding of 14-3-3 to Myosin Phosphatase

2008 ◽  
Vol 19 (3) ◽  
pp. 1062-1071 ◽  
Author(s):  
Yasuhiko Koga ◽  
Mitsuo Ikebe
Keyword(s):  
Light Chain ◽  
Myosin Light Chain ◽  
Regulatory Mechanism ◽  
Kinase Inhibitor ◽  
Myosin Ii ◽  
Critical Role ◽  
Rho Kinase ◽  
Myosin Phosphatase ◽  
Dependent Cell ◽  
Direct Binding

Myosin II phosphorylation–dependent cell motile events are regulated by myosin light-chain (MLC) kinase and MLC phosphatase (MLCP). Recent studies have revealed myosin phosphatase targeting subunit (MYPT1), a myosin-binding subunit of MLCP, plays a critical role in MLCP regulation. Here we report the new regulatory mechanism of MLCP via the interaction between 14-3-3 and MYPT1. The binding of 14-3-3β to MYPT1 diminished the direct binding between MYPT1 and myosin II, and 14-3-3β overexpression abolished MYPT1 localization at stress fiber. Furthermore, 14-3-3β inhibited MLCP holoenzyme activity via the interaction with MYPT1. Consistently, 14-3-3β overexpression increased myosin II phosphorylation in cells. We found that MYPT1 phosphorylation at Ser472 was critical for the binding to 14-3-3. Epidermal growth factor (EGF) stimulation increased both Ser472 phosphorylation and the binding of MYPT1-14-3-3. Rho-kinase inhibitor inhibited the EGF-induced Ser472 phosphorylation and the binding of MYPT1-14-3-3. Rho-kinase specific siRNA also decreased EGF-induced Ser472 phosphorylation correlated with the decrease in MLC phosphorylation. The present study revealed a new RhoA/Rho-kinase–dependent regulatory mechanism of myosin II phosphorylation by 14-3-3 that dissociates MLCP from myosin II and attenuates MLCP activity.

Modulation of uterine resistance artery lumen diameter by calcium and G protein activation during pregnancy

1994 ◽  
Vol 267 (3) ◽  
pp. H952-H961 ◽  
Author(s):  
G. D'Angelo ◽  
G. Osol
Keyword(s):  
Smooth Muscle ◽  
G Protein ◽  
G Proteins ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Lumen Diameter ◽  
Maximal Response ◽  
Adrenergic Stimulation ◽  
Myosin Light Chain Phosphatase ◽  
Arterial Lumen

The purpose of this study was to determine whether the increased sensitivity of uterine resistance arteries from late pregnant (LP) rats to alpha-adrenergic stimulation is due to an alteration in the fundamental relationship between cytosolic calcium (Ca2+) and arterial lumen diameter. Uterine arcuate arteries were permeabilized with Staphylococcus aureus alpha-toxin under optimal conditions and constricted to varying degrees with discrete Ca2+ concentrations at a distending pressure of 50 mmHg. Arterial segments from nonpregnant (NP) and LP rats exhibited similar Ca2+/lumen diameter characteristics. Ca2+ (0.1 microM) produced appreciable constriction, and lumen diameter decreased steeply between 0.175 and 0.25 microM Ca2+; maximal responses were attained with 0.5 microM Ca2+. Activation of guanine nucleotide binding proteins (G proteins) with guanosine 5'-triphosphate (GTP; 1-100 microM), as reportedly occurs during alpha-adrenergic stimulation, potentiated the Ca(2+)-induced constriction by 121 and 79% in arteries from LP and NP rats, respectively. No significant differences between the two animal groups were noted. Guanosine 5'-O-(gamma-thiotriphosphate) (GTP gamma S; 0.1-10 microM), a nonhydrolyzable analogue of GTP, effected a larger potentiating effect over that maximal response caused by GTP in arteries from NP rats. Ca(2+)- and Ca2+/GTP-induced constrictions were more potently reversed by guanosine 5'-O-(beta-thiodiphosphate) (GDP beta S)., a competitive inhibitor of GTP, in arteries from NP rats. These data suggest that pregnancy-induced increases in sensitivity to alpha-adrenergic stimulation may be related to altered G protein cycling rates, such that G proteins in smooth muscle cells in arcuate arteries from NP rats are more susceptible to deactivation. Alternatively, consistent with the model of G protein-mediated inhibition of myosin light chain phosphatase, myosin light chain phosphatase activity may be enhanced in uterine vascular smooth muscle from NP rats relative to that from LP rats.

scholarly journals Myosin Motors and Not Actin Comets Are Mediators of the Actin-based Golgi-to-Endoplasmic Reticulum Protein Transport

2003 ◽  
Vol 14 (2) ◽  
pp. 445-459 ◽  
Author(s):  
Juan M. Durán ◽  
Ferran Valderrama ◽  
Susana Castel ◽  
Juana Magdalena ◽  
Mónica Tomás ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Light Chain ◽  
Shiga Toxin ◽  
Actin Filaments ◽  
Protein Transport ◽  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Nonmuscle Myosin Ii ◽  
Myosin Motors

We have previously reported that actin filaments are involved in protein transport from the Golgi complex to the endoplasmic reticulum. Herein, we examined whether myosin motors or actin comets mediate this transport. To address this issue we have used, on one hand, a combination of specific inhibitors such as 2,3-butanedione monoxime (BDM) and 1-[5-isoquinoline sulfonyl]-2-methyl piperazine (ML7), which inhibit myosin and the phosphorylation of myosin II by the myosin light chain kinase, respectively; and a mutant of the nonmuscle myosin II regulatory light chain, which cannot be phosphorylated (MRLC2AA). On the other hand, actin comet tails were induced by the overexpression of phosphatidylinositol phosphate 5-kinase. Cells treated with BDM/ML7 or those that express the MRLC2AA mutant revealed a significant reduction in the brefeldin A (BFA)-induced fusion of Golgi enzymes with the endoplasmic reticulum (ER). This delay was not caused by an alteration in the formation of the BFA-induced tubules from the Golgi complex. In addition, the Shiga toxin fragment B transport from the Golgi complex to the ER was also altered. This impairment in the retrograde protein transport was not due to depletion of intracellular calcium stores or to the activation of Rho kinase. Neither the reassembly of the Golgi complex after BFA removal nor VSV-G transport from ER to the Golgi was altered in cells treated with BDM/ML7 or expressing MRLC2AA. Finally, transport carriers containing Shiga toxin did not move into the cytosol at the tips of comet tails of polymerizing actin. Collectively, the results indicate that 1) myosin motors move to transport carriers from the Golgi complex to the ER along actin filaments; 2) nonmuscle myosin II mediates in this process; and 3) actin comets are not involved in retrograde transport.

scholarly journals 220- and 130-kDa MLCKs have distinct tissue distributions and intracellular localization patterns

2002 ◽  
Vol 282 (3) ◽  
pp. C451-C460 ◽  
Author(s):  
Emily K. Blue ◽  
Zoe M. Goeckeler ◽  
Yijun Jin ◽  
Ling Hou ◽  
Shelley A. Dixon ◽  
...  
Keyword(s):  
Intracellular Trafficking ◽  
Myosin Light Chain ◽  
Adult Mouse ◽  
Intracellular Localization ◽  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Functional Roles ◽  
Nonmuscle Myosin Ii ◽  
Mouse Tissues

To better understand the distinct functional roles of the 220- and 130-kDa forms of myosin light chain kinase (MLCK), expression and intracellular localization were determined during development and in adult mouse tissues. Northern blot, Western blot, and histochemical studies show that the 220-kDa MLCK is widely expressed during development as well as in several adult smooth muscle and nonmuscle tissues. The 130-kDa MLCK is highly expressed in all adult tissues examined and is also detectable during embryonic development. Colocalization studies examining the distribution of 130- and 220-kDa mouse MLCKs revealed that the 130-kDa MLCK colocalizes with nonmuscle myosin IIA but not with myosin IIB or F-actin. In contrast, the 220-kDa MLCK did not colocalize with either nonmuscle myosin II isoform but instead colocalizes with thick interconnected bundles of F-actin. These results suggest that in vivo, the physiological functions of the 220- and 130-kDa MLCKs are likely to be regulated by their intracellular trafficking and distribution.

Essential light chain of Drosophila nonmuscle myosin II

1995 ◽  
Vol 16 (5) ◽  
pp. 491-498 ◽  
Author(s):  
Kevin A. Edwards ◽  
Xiao-Jia Chang ◽  
Daniel P. Kiehart
Keyword(s):  
Light Chain ◽  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Essential Light Chain ◽  
Nonmuscle Myosin Ii

Telokin expression and the effect of hypoxia on its phosphorylation status in smooth muscle cells from small and large pulmonary arteries

2008 ◽  
Vol 294 (6) ◽  
pp. L1166-L1173 ◽  
Author(s):  
Jane A. Madden ◽  
Mark W. Dantuma ◽  
Elena A. Sorokina ◽  
Dorothee Weihrauch ◽  
Jack G. Kleinman
Keyword(s):  
Smooth Muscle ◽  
Muscle Cell ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Muscle Relaxation ◽  
Cerebral Arteries ◽  
Pulmonary Arteries ◽  
Smooth Muscle Relaxation ◽  
Myosin Phosphatase ◽  
Mlc Phosphorylation

Small pulmonary arteries (SPA), <500 μm diameter of the cat, constrict when exposed to hypoxia, whereas larger arteries (large pulmonary arteries; LPA), >800 μm diameter, show little or no response. It is unknown why different contractile responses occur within the same vascular bed, but activator or repressor proteins within the smooth muscle cell (SMC) can modify myosin phosphatase and myosin light chain kinase (MLCK), thereby influencing the phosphorylation state of myosin light chain (MLC) and ultimately, contraction. Telokin, a protein with a sequence identical to the COOH-terminal domain of MLCK, is expressed in smooth muscle where in its phosphorylated state it inhibits myosin phosphatase, binds to unphosphorylated myosin, and helps maintain smooth muscle relaxation. We measured telokin mRNA and telokin protein in smooth muscle from different diameter feline pulmonary arteries and sought to determine whether changes in the phosphorylation status of telokin and MLC occurred during hypoxia. In pulmonary arteries, telokin expression varied inversely with artery diameter, but cerebral arteries showed neither telokin protein nor telokin mRNA. Although telokin and MLC were distributed uniformly throughout the SPA muscle cell cytoplasm, they were not colocalized. During hypoxia, telokin dephosphorylated, and MLC became increasingly phosphorylated in SPA SMC, whereas in LPA SMC there was no change in either telokin or MLC phosphorylation. When LPA SMC were exposed to phenylephrine, MLC phosphorylation increased with no change in telokin phosphorylation. These results suggest that in SPA, phosphorylated telokin may help maintain relaxation under unstimulated conditions, whereas in LPA, telokin's function remains undetermined.

Native nonmuscle myosin II stability and light chain binding inDrosophila melanogaster

2006 ◽  
Vol 63 (10) ◽  
pp. 604-622 ◽  
Author(s):  
Josef D. Franke ◽  
Amanda L. Boury ◽  
Noel J. Gerald ◽  
Daniel P. Kiehart
Keyword(s):  
Light Chain ◽  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Nonmuscle Myosin Ii
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