scholarly journals Myosin light chain kinase regulates cell polarization independently of membrane tension or Rho kinase

2015 ◽  
Vol 209 (2) ◽  
pp. 275-288 ◽  
Author(s):  
Sunny S. Lou ◽  
Alba Diz-Muñoz ◽  
Orion D. Weiner ◽  
Daniel A. Fletcher ◽  
Julie A. Theriot
Keyword(s):  
Cell Polarity ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Rho Kinase ◽  
Model System ◽  
Cell Polarization ◽  
Membrane Tension ◽  
Specific Mechanism

Cells polarize to a single front and rear to achieve rapid actin-based motility, but the mechanisms preventing the formation of multiple fronts are unclear. We developed embryonic zebrafish keratocytes as a model system for investigating establishment of a single axis. We observed that, although keratocytes from 2 d postfertilization (dpf) embryos resembled canonical fan-shaped keratocytes, keratocytes from 4 dpf embryos often formed multiple protrusions despite unchanged membrane tension. Using genomic, genetic, and pharmacological approaches, we determined that the multiple-protrusion phenotype was primarily due to increased myosin light chain kinase (MLCK) expression. MLCK activity influences cell polarity by increasing myosin accumulation in lamellipodia, which locally decreases protrusion lifetime, limiting lamellipodial size and allowing for multiple protrusions to coexist within the context of membrane tension limiting protrusion globally. In contrast, Rho kinase (ROCK) regulates myosin accumulation at the cell rear and does not determine protrusion size. These results suggest a novel MLCK-specific mechanism for controlling cell polarity via regulation of myosin activity in protrusions.

Lanthanum chloride causes blood–brain barrier disruption through intracellular calcium-mediated RhoA/Rho kinase signaling and myosin light chain kinase

Metallomics ◽  
2020 ◽  
Author(s):  
Jie Wu ◽  
Jinghua Yang ◽  
Miao Yu ◽  
Wenchang Sun ◽  
Yarao Han ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Intracellular Calcium ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Rho Kinase ◽  
Endothelial Barrier ◽  
Blood Brain Barrier Disruption ◽  
Intracellular Ca ◽  
Brain Barrier Disruption

Lanthanum caused endothelial barrier hyperpermeability, loss of VE-cadherin and rearrangement of the actin cytoskeleton, though intracellular Ca2+-mediated RhoA/ROCK and MLCK pathways.

Rat pulmonary arterial smooth muscle myosin light chain kinase and phosphatase activities decrease with age

2006 ◽  
Vol 290 (3) ◽  
pp. L509-L516 ◽  
Author(s):  
J. Belik ◽  
Ewa Kerc ◽  
Mary D. Pato
Keyword(s):  
Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Rho Kinase ◽  
Adult Tissue ◽  
Adult Rat ◽  
Pulmonary Arterial ◽  
Pulmonary Arterial Smooth Muscle ◽  
Specific Activities

We and others have shown that the fetal pulmonary arterial smooth muscle potential for contraction and relaxation is significantly reduced compared with the adult. Whether these developmental changes relate to age differences in the expression and/or activity of key enzymes regulating the smooth muscle mechanical properties has not been previously evaluated. Therefore, we studied the catalytic activities and expression of myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP) catalytic (PP1cδ) and regulatory (MYPT) subunits in late fetal, early newborn, and adult rat intrapulmonary arterial tissues. In keeping with the greater force development and relaxation of adult pulmonary artery, Western blot analysis showed that the MLCK, MYPT, and PP1cδ contents increased significantly with age and were highest in the adult rat. In contrast, their specific activities (activity/enzyme content) were significantly higher in the fetal compared with the adult tissue. The fetal and newborn pulmonary arterial muscle relaxant response to the Rho-kinase inhibitor Y-27632 was greater than the adult tissue. In addition to the 130-kDa isoform of MLCK, we documented the presence of minor higher-molecular-weight embryonic isoforms in the fetus and newborn. During fetal life, the lung pulmonary arterial MLCK- and MLCP-specific activities are highest and appear to be related to Rho-kinase activation during lung morphogenesis.

373 Role of myosin light chain kinase and Rho kinase in carbachol-induced contractions of human detrusor smooth muscle

2012 ◽  
Vol 11 (1) ◽  
pp. e373
Author(s):  
C. Protzel ◽  
T. Kirschstein ◽  
K. Porath ◽  
T. Sellmann ◽  
R. Koehling ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Rho Kinase ◽  
Detrusor Smooth Muscle ◽  
Human Detrusor

scholarly journals Nonmuscle Myosin IIA Regulates Platelet Contractile Forces Through Rho Kinase and Myosin Light-Chain Kinase

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Shirin Feghhi ◽  
Wes W. Tooley ◽  
Nathan J. Sniadecki
Keyword(s):  
Atpase Activity ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Rho Kinase ◽  
Myosin Atpase ◽  
Nonmuscle Myosin ◽  
Myosin Phosphorylation ◽  
Myosin Atpase Activity ◽  
Contractile Forces

Platelet contractile forces play a major role in clot retraction and help to hold hemostatic clots against the vessel wall. Platelet forces are produced by its cytoskeleton, which is composed of actin and nonmuscle myosin filaments. In this work, we studied the role of Rho kinase, myosin light-chain kinase, and myosin in the generation of contractile forces by using pharmacological inhibitors and arrays of flexible microposts to measure platelet forces. When platelets were seeded onto microposts, they formed aggregates on the tips of the microposts. Forces produced by the platelets in the aggregates were measured by quantifying the deflection of the microposts, which bent in proportion to the force of the platelets. Platelets were treated with small molecule inhibitors of myosin activity: Y-27632 to inhibit the Rho kinase (ROCK), ML-7 to inhibit myosin light-chain kinase (MLCK), and blebbistatin to inhibit myosin ATPase activity. ROCK inhibition reduced platelet forces, demonstrating the importance of the assembly of actin and myosin phosphorylation in generating contractile forces. Similarly, MLCK inhibition caused weaker platelet forces, which verifies that myosin phosphorylation is needed for force generation in platelets. Platelets treated with blebbistatin also had weaker forces, which indicates that myosin's ATPase activity is necessary for platelet forces. Our studies demonstrate that myosin ATPase activity and the regulation of actin–myosin assembly by ROCK and MLCK are needed for the generation of platelet forces. Our findings illustrate and explain the importance of myosin for clot compaction in hemostasis and thrombosis.

scholarly journals Slit and Netrin-1 guide cranial motor axon pathfinding via Rho-kinase, myosin light chain kinase and myosin II

2010 ◽  
Vol 5 (1) ◽  
pp. 16 ◽  
Author(s):  
Ailish Murray ◽  
Arifa Naeem ◽  
Sarah H Barnes ◽  
Uwe Drescher ◽  
Sarah Guthrie
Keyword(s):  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Myosin Ii ◽  
Rho Kinase ◽  
Motor Axon ◽  
Axon Pathfinding

scholarly journals Myosin light chain kinase activation and calcium sensitization in smooth muscle in vivo

2008 ◽  
Vol 295 (2) ◽  
pp. C358-C364 ◽  
Author(s):  
Yusuke Mizuno ◽  
Eiji Isotani ◽  
Jian Huang ◽  
Hailei Ding ◽  
James T. Stull ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Kinase Inhibitor ◽  
Fluorescent Proteins ◽  
Rho Kinase ◽  
Kinase Activation ◽  
Calphostin C

Ca2+/calmodulin (CaM)-dependent phosphorylation of myosin regulatory light chain (RLC) in smooth muscle by myosin light chain kinase (MLCK) and dephosphorylation by myosin light chain phosphatase (MLCP) are subject to modulatory cascades that influence the sensitivity of RLC phosphorylation and hence contraction to intracellular Ca2+ concentration ([Ca2+]i). We designed a CaM-sensor MLCK containing smooth muscle MLCK fused to two fluorescent proteins linked by the MLCK CaM-binding sequence to measure kinase activation in vivo and expressed it specifically in mouse smooth muscle. In phasic bladder muscle, there was greater RLC phosphorylation and force relative to MLCK activation and [Ca2+]i with carbachol (CCh) compared with KCl treatment, consistent with agonist-dependent inhibition of MLCP. The dependence of force on MLCK activity was nonlinear such that at higher concentrations of CCh, force increased with no change in the net 20% activation of MLCK. A significant but smaller amount of MLCK activation was found during the sustained contractile phase. MLCP inhibition may occur through RhoA/Rho-kinase and/or PKC with phosphorylation of myosin phosphatase targeting subunit-1 (MYPT1) and PKC-potentiated phosphatase inhibitor (CPI-17), respectively. CCh treatment, but not KCl, resulted in MYPT1 and CPI-17 phosphorylation. Both Y27632 (Rho-kinase inhibitor) and calphostin C (PKC inhibitor) reduced CCh-dependent force, RLC phosphorylation, and phosphorylation of MYPT1 (Thr694) without changing MLCK activation. Calphostin C, but not Y27632, also reduced CCh-induced phosphorylation of CPI-17. CCh concentration responses showed that phosphorylation of CPI-17 was more sensitive than MYPT1. Thus the onset of agonist-induced contraction in phasic smooth muscle results from the rapid and coordinated activation of MLCK with hierarchical inhibition of MLCP by CPI-17 and MYPT1 phosphorylation.

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