Intracellular signal transduction for migration and actin remodeling in vascular smooth muscle cells after sphingosylphosphorylcholine stimulation.
Molecular mechanisms underlying migration of vascular smooth muscle cells (VSMCs) toward sphingosylphosphorylcholine (SPC) were analyzed in light of the hypothesis that remodeling of the actin cytoskeleton should be involved. After SPC stimulation, mitogen-activated protein kinases (MAPKs), including p38 MAPK (p38) and p42/44 MAPK (p42/44), were found to be phosphorylated. Migration of cells toward SPC was reduced in the presence of SB-203580, an inhibitor of p38, but not PD-98059, an inhibitor of p42/44. Pertussis toxin (PTX), a Gi protein inhibitor, induced an inhibitory effect on p38 phosphorylation and VSMC migration. Myosin light chain (MLC) phosphorylation occurred after SPC stimulation with or without pretreatment with SB-203580 or PTX. The MLC kinase inhibitor ML-7 and the Rho kinase inhibitor Y-27632 inhibited MLC phosphorylation but only partially inhibited SPC-directed migration. Complete inhibition was achieved with the addition of SB-203580. After SPC stimulation, the actin cytoskeleton formed thick bundles of actin filaments around the periphery of cells, and the cells were surrounded by elongated filopodia, i.e., magunapodia. The peripheral actin bundles consisted of alpha- and beta-actin, but magunapodia consisted exclusively of beta-actin. Such a remodeling of actin was reversed by addition of SB-203580 and PTX, but not ML-7 or Y-27632. Taken together, our biochemical and morphological data confirmed the regulation of actin remodeling and suggest that VSMCs migrate toward SPC, not only by an MLC phosphorylation-dependent pathway, but also by an MLC phosphorylation-independent pathway.
Li
Sheng
S
Department of Molecular and Cellular Pharmacology, Faculty of Medicine, Gunma University Graduate School of Medicine, 3-39-22 Showa-Machi, Maebashi, Gunma 371-8511, Japan.
Tanaka
Hideyuki
H
Wang
Hong Hui
HH
Yoshiyama
Shinji
S
Kumagai
Hiroyuki
H
Nakamura
Akio
A
Brown
Dawn L
DL
Thatcher
Sean E
SE
Wright
Gary L
GL
Kohama
Kazuhiro
K
D000199:Actins / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D000577:Amides / Q000494:pharmacology; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology; D006168:Guinea Pigs; D007093:Imidazoles / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism / Q000502:physiology; D009281:Naphthalenes / Q000494:pharmacology; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D000199:Actins; D000577:Amides; D001381:Azepines; D004791:Enzyme Inhibitors; D007093:Imidazoles; D018994:Myosin Light Chains; D009281:Naphthalenes; D011725:Pyridines; C005356:sphingosine phosphorylcholine; D010767:Phosphorylcholine; C070571:ML 7; C108830:Y 27632; D037342:Pertussis Toxin; D019950:Mitogen-Activated Protein Kinase 1; D048051:p38 Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D019204:GTP-Binding Proteins; D013110:Sphingosine; C093642:SB 203580