Convulxin induces platelet shape change through myosin light chain kinase and Rho kinase

Abstract The initial event in platelet activation is the reorganization of the cytoskeleton causing the platelets to change from a discoid to a spiculated spheroid shape. Platelet shape change is primarily regulated by the phosphorylation of myosin light chain kinase. We have shown that this process is mediated through both calcium-dependent and calcium-independent Rho kinase pathways. CPI-17, a Protein kinase C (PKC) phosphorylated inhibitory protein of myosin light chain phosphatase, has been shown to have a role in platelet shape change downstream of thrombin-induced platelet activation. CPI-17 is a 17 kDa protein expressed in human platelets shown to inhibit myosin light chain phosphotase activity via PKCs. In this study we examined the role of CPI-17 in ADP-induced shape change and phosphorylation of CPI-17, downstream of the Gq coupled, P2Y1, and the Gi coupled, P2Y12 receptors. CPI-17 phosphorylation occurred upon activation of platelets with 2MeSADP. This phosphorylation was abolished in the presence of the P2Y1 receptor antagonist, MRS-2179. These results indicated that Gq signaling is important for platelet shape change and phosphorylation of CPI-17. In the presence of the calcium chelator, BAPTA, platelets changed shape in response to 2MeSADP; CPI-17 phosphorylation, however, was unaffected by BAPTA treatment under these conditions. However, CPI-17 phosphorylation was inhibited in the presence of the pan PKC inhibitors. These results indicate that CPI-17 phosphorylation occurs downstream of PKC activation. In the presence of BAPTA, treatment with PKC inhibitors decreased platelet shape change possibly due to reduced CPI-17 phosphorylation. The shape change caused by p160ROCK downstream of G12/13 pathways was unaffected by pan PKC inhibitors, but abolished by p160ROCK inhibitors H1152 or Y27632. Platelets incubated with BAPTA, pan PKC inhibitors, and p160ROCK inhibitor H1152, abolished ADP-induced platelet shape change and CPI-17 phosphorylation. In conclusion, ADP-induced platelet shape change occurs through a Gq-mediated, calcium-independent signaling pathway regulated by CPI-17 phosphorylation via PKC activation.

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Mildly oxidised low density lipoprotein induces platelet shape change via Rho-kinase-dependent phosphorylation of myosin light chain and moesin

FEBS Letters ◽

10.1016/s0014-5793(99)01762-7 ◽

2000 ◽

Vol 466 (1) ◽

pp. 70-74 ◽

Cited By ~ 26

Author(s):

Michaela Retzer ◽

Wolfgang Siess ◽

Markus Essler

Keyword(s):

Light Chain ◽

Myosin Light Chain ◽

Shape Change ◽

Low Density Lipoprotein ◽

Rho Kinase ◽

Density Lipoprotein ◽

Low Density ◽

Oxidised Low Density Lipoprotein ◽

Platelet Shape

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Roles of myosin light-chain kinase in platelet shape change and aggregation

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research ◽

10.1016/0167-4889(94)90222-4 ◽

1994 ◽

Vol 1223 (2) ◽

pp. 163-169 ◽

Cited By ~ 20

Author(s):

Yoshiaki Hashimoto ◽

Hiroyuki Sasaki ◽

Masako Togo ◽

Kazuhisa Tsukamoto ◽

Yukio Horie ◽

...

Keyword(s):

Light Chain ◽

Myosin Light Chain Kinase ◽

Myosin Light Chain ◽

Shape Change ◽

Platelet Shape

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cAMP signaling regulates platelet myosin light chain (MLC) phosphorylation and shape change through targeting the RhoA-Rho kinase-MLC phosphatase signaling pathway

Blood ◽

10.1182/blood-2013-03-487850 ◽

2013 ◽

Vol 122 (20) ◽

pp. 3533-3545 ◽

Cited By ~ 61

Author(s):

Ahmed Aburima ◽

Katie S. Wraith ◽

Zaher Raslan ◽

Robert Law ◽

Simbarashe Magwenzi ◽

...

Keyword(s):

Light Chain ◽

Myosin Light Chain ◽

Shape Change ◽

Rho Kinase ◽

Camp Signaling ◽

Key Points ◽

Rhoa Kinase ◽

Mlc Phosphorylation ◽

Kinase A ◽

Platelet Shape

Key Points Protein kinase A (PKA) phosphorylates RhoA on serine188 to inhibit RhoA membrane translocation and RhoA kinase (ROCK) signaling. Inhibition of RhoA/ROCK2 promotes myosin light chain (MLC) phosphatase activity, which prevents the phosphorylation of MLC and platelet shape change.

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

Metallomics ◽

10.1039/d0mt00187b ◽

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.

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Sinusoidal endothelial fenestrae organization regulated by myosin light chain kinase and Rho-kinase in cultured rat sinusoidal endothelial cells

Hepatology Research ◽

10.1016/j.hepres.2004.08.002 ◽

2004 ◽

Vol 30 (3) ◽

pp. 169-174 ◽

Cited By ~ 7

Author(s):

H YOKOMORI

Keyword(s):

Endothelial Cells ◽

Light Chain ◽

Myosin Light Chain Kinase ◽

Myosin Light Chain ◽

Rho Kinase ◽

Sinusoidal Endothelial Cells ◽

Sinusoidal Endothelial Fenestrae

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

The Journal of Cell Biology ◽

10.1083/jcb.201409001 ◽

2015 ◽

Vol 209 (2) ◽

pp. 275-288 ◽

Cited By ~ 24

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.

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

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00145.2005 ◽

2006 ◽

Vol 290 (3) ◽

pp. L509-L516 ◽

Cited By ~ 13

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.

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