title: Role of MARCKS in regulating endothelial cell proliferation.
abstract: Myristoylated alanine-rich C kinase substrate (MARCKS), as a specific protein kinase C (PKC) substrate, mediates PKC signaling through its phosphorylation and subsequent modification of its association with filamentous actin (F-actin) and calmodulin (CaM). PKC has long been implicated in cell proliferation, and recent studies have suggested that MARCKS may function as a cell growth suppressor. Therefore, in the present study, we investigated MARCKS protein expression, distribution, and phosphorylation in preconfluent and confluent bovine pulmonary microvascular endothelial cells (BPMEC) in the presence or absence of the vascular endothelial growth factor (VEGF). In addition, we examined functional alterations of MARCKS in these cells by studying the association of MARCKS with F-actin and CaM-dependent myosin light chain (MLC) phosphorylation. Our results indicate that MARCKS protein is downregulated during BPMEC proliferation. Decreased MARCKS association with F-actin, increased actin polymerization, and CaM-dependent MLC phosphorylation appear to mediate cell shape changes and motility during BPMEC growth. In contrast, VEGF stimulated MARCKS phosphorylation without alteration of protein expression during BPMEC proliferation, which may result in reduced interaction between MARCKS and actin or CaM, leading to actin reorganization and MLC phosphorylation. Our data suggest a regulatory role of MARCKS during endothelial cell proliferation.
authors.affiliation: Department of Internal Medicine, Pulmonary and Critical Care Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio 45267, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
authors.forename: B S
authors.initials: BS
authors.lastname: Neltner
authors.forename: H W
authors.initials: HW
authors.lastname: Davis
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002455:Cell Division / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D048429:Cell Size / Q000502:physiology; D002478:Cells, Cultured; D015536:Down-Regulation / Q000502:physiology; D016228:Endothelial Growth Factors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology* / Q000502:physiology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008222:Lymphokines / Q000494:pharmacology; D008565:Membrane Proteins; D018994:Myosin Light Chains / Q000378:metabolism; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D010766:Phosphorylation / Q000187:drug effects; D011108:Polymers / Q000378:metabolism; D011506:Proteins / Q000502:physiology*; D014018:Tissue Distribution; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D000199:Actins; D016228:Endothelial Growth Factors; D047908:Intracellular Signaling Peptides and Proteins; D008222:Lymphokines; C000619710:MARCKS protein, human; D008565:Membrane Proteins; D018994:Myosin Light Chains; D011108:Polymers; D011506:Proteins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000076250:Myristoylated Alanine-Rich C Kinase Substrate