scholarly journals Albumin causes increased myosin light chain kinase expression in astrocytes via p38 mitogen-activated protein kinase

2011 ◽  
Vol 89 (6) ◽  
pp. 852-861 ◽  
Author(s):  
Janet L. Rossi ◽  
Hantamalala Ralay Ranaivo ◽  
Fatima Patel ◽  
MaryAnn Chrzaszcz ◽  
Charu Venkatesan ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Kinase Expression

Phosphorylation and activation of smooth muscle myosin light chain kinase by MAP kinase and cyclin-dependent kinase-1

1996 ◽  
Vol 74 (4) ◽  
pp. 549-557 ◽  
Author(s):  
Donna L. Morrison ◽  
Jasbinder S. Sanghera ◽  
Justine Stewart ◽  
Steven L. Pelech ◽  
Cindy Sutherland ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Smooth Muscle Myosin ◽  
Mitogen Activated Protein Kinase ◽  
Cyclin Dependent Kinase ◽  
Mitogen Activated Protein ◽  
Muscle Myosin

Smooth muscle myosin light chain kinase (MLCK) features several consensus sites of phosphorylation by proline-directed protein serine/threonine kinases. The phosphorylation of MLCK by two proline-directed kinases isolated from sea star oocytes, i.e., p44mpk (Mpk, a mitogen-activated protein kinase homologue) and cyclin-dependent kinase-1 (CDK1, also known as p34cdc2), was investigated. Chicken gizzard MLCK was phosphorylated on seryl and fhreonyl residues by both Mpk and CDK1. Phosphorylation of MLCK to 0.6 mol Pi/mol by Mpk increased the Vmax of phosphotransferase activity towards a synthetic peptide corresponding to residues 11–23 of the 20-kDa light chain of myosin by 1.6-fold. Phosphorylation of MLCK to 1.0 mol Pi/mol by CDK1 increased the Vmax by 2.3-fold. Phosphorylation by either kinase had no significant effect on the concentration of calmodulin required for half-maximal activation of MLCK. Analysis of the phosphorylation of synthetic peptides containing consensus phosphorylation sites for Mpk and CDK1 indicated that the major site of phosphorylation in MLCK by Mpk was Ser-834, and by CDK1 was Thr-283. Both of these sites are located outside the cafmodulin-binding site (residues 796–815), consistent with the observation that phosphorylation by Mpk or CDK1 was unaffected by the presence of bound Ca2+/calmodulin. These results indicate that MLCK activity may be regulated by phosphorylation catalyzed by proline-directed kinases, possibly directed at Thr-40 and Thr-43 at the amino terminus of MLCK.Key words: myosin light chain kinase, mitogen-activated protein kinase, cyclin-dependent kinase.

Regulation of polymorphonuclear leukocyte phagocytosis by myosin light chain kinase after activation of mitogen-activated protein kinase

Blood ◽  
2000 ◽  
Vol 95 (7) ◽  
pp. 2407-2412 ◽  
Author(s):  
Pamela J. Mansfield ◽  
James A. Shayman ◽  
Laurence A. Boxer
Keyword(s):  
Map Kinase ◽  
Light Chain ◽  
Polymorphonuclear Leukocyte ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Erk Activation ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

Abstract Polymorphonuclear leukocyte (PMNL) phagocytosis mediated by FcγRII proceeds in concert with activation of the mitogen-activated protein (MAP) kinase, extracellular signal-regulated kinase ERK2. We hypothesized that myosin light chain kinase (MLCK) could be phosphorylated and activated by ERK, thereby linking the MAP kinase pathway to the activation of cytoskeletal components required for pseudopod formation. To explore this potential linkage, PMNLs were challenged with antibody-coated erythrocytes (EIgG). Peak MLCK activity, 3-fold increased over controls, occurred at 4 to 6 minutes, corresponding with the peak rate of target ingestion and ERK2 activity. The MLCK inhibitor ML-7 (10 μmol/L) inhibited both phagocytosis and MLCK activity to basal values, thereby providing further support for the linkage between the functional response and the requirement for MLCK activation. The MAPK kinase (MEK) inhibitor PD098059 inhibited phagocytosis, MLCK activity, and ERK2 activity by 80% to 90%. To directly link ERK activation to MLCK activation, ERK2 was immunoprecipitated from PMNLs after EIgG ingestion. The isolated ERK2 was incubated with PMNL cytosol as a source of unactivated MLCK and with MLCK substrate; under these conditions ERK2 activated MLCK, resulting in phosphorylation of the MLCK substrate or of the myosin light chain itself. Because MLCK activates myosin, we evaluated the effect of directly inhibiting myosin adenosine triphosphatase using 2,3-butanedione monoxime (BDM) and found that phagocytosis was inhibited by more than 90% but MLCK activity remained unaffected. These results are consistent with the interpretation that MEK activates ERK, ERK2 then activates MLCK, and MLCK activates myosin. MLCK activation is a critical step in the cytoskeletal changes resulting in pseudopod formation.

Regulation of polymorphonuclear leukocyte phagocytosis by myosin light chain kinase after activation of mitogen-activated protein kinase

Blood ◽  
2000 ◽  
Vol 95 (7) ◽  
pp. 2407-2412 ◽  
Author(s):  
Pamela J. Mansfield ◽  
James A. Shayman ◽  
Laurence A. Boxer
Keyword(s):  
Map Kinase ◽  
Light Chain ◽  
Polymorphonuclear Leukocyte ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Erk Activation ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

Polymorphonuclear leukocyte (PMNL) phagocytosis mediated by FcγRII proceeds in concert with activation of the mitogen-activated protein (MAP) kinase, extracellular signal-regulated kinase ERK2. We hypothesized that myosin light chain kinase (MLCK) could be phosphorylated and activated by ERK, thereby linking the MAP kinase pathway to the activation of cytoskeletal components required for pseudopod formation. To explore this potential linkage, PMNLs were challenged with antibody-coated erythrocytes (EIgG). Peak MLCK activity, 3-fold increased over controls, occurred at 4 to 6 minutes, corresponding with the peak rate of target ingestion and ERK2 activity. The MLCK inhibitor ML-7 (10 μmol/L) inhibited both phagocytosis and MLCK activity to basal values, thereby providing further support for the linkage between the functional response and the requirement for MLCK activation. The MAPK kinase (MEK) inhibitor PD098059 inhibited phagocytosis, MLCK activity, and ERK2 activity by 80% to 90%. To directly link ERK activation to MLCK activation, ERK2 was immunoprecipitated from PMNLs after EIgG ingestion. The isolated ERK2 was incubated with PMNL cytosol as a source of unactivated MLCK and with MLCK substrate; under these conditions ERK2 activated MLCK, resulting in phosphorylation of the MLCK substrate or of the myosin light chain itself. Because MLCK activates myosin, we evaluated the effect of directly inhibiting myosin adenosine triphosphatase using 2,3-butanedione monoxime (BDM) and found that phagocytosis was inhibited by more than 90% but MLCK activity remained unaffected. These results are consistent with the interpretation that MEK activates ERK, ERK2 then activates MLCK, and MLCK activates myosin. MLCK activation is a critical step in the cytoskeletal changes resulting in pseudopod formation.

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