Activation of DNA synthesis and AP-1 by profilin, an actin-binding protein, via binding to a cell surface receptor in cultured rat mesangial cells.
Profilin is known to bind to actin monomers (to regulate actin polymerization) and to phosphatidylinositol-4,5-bisphosphate (to inhibit hydrolysis by unphosphorylated phospholipase C-gammal). It was recently reported that profilin is overexpressed in glomerular mesangial cells (MC) of rats with anti-Thy-1.1-induced glomerulonephritis and is accumulated in the extracellular space around MC. In this study, the biologic activities of extracellular profilin were examined. Scatchard analysis indicated the existence of a single class of cell surface binding sites, with similar equilibrium dissociation constants for purified splenic profilin and recombinant profilin, in cultured rat MC. Profilin increased [(3)H]thymidine incorporation in a dose-dependent manner and produced additive effects on platelet-derived growth factor-induced [(3)H]thymidine incorporation. Profilin increased AP-1 DNA-binding activity in a concentration-dependent (ED(50) = 30 nM) and time-dependent manner after transient c-jun gene expression, as measured using gel-shift assays and competitive reverse transcription-PCR. Pretreatment of profilin with an anti-profilin inhibitory antibody suppressed profilin-induced AP-1 activation and [(3)H]thymidine incorporation. Furthermore, profilin induced rapid transient activation of protein kinase C, and staurosporine and H-7 reduced the profilin-induced activation of AP-1, suggesting protein kinase C-dependent activation of AP-1. These findings indicate that profilin in the extracellular space can bind to cell surface receptors of MC and act as an inducer of signal transduction. These results suggest that extracellular profilin may be involved in the progression of glomerular diseases, by affecting cell growth.
Tamura
Masahito
M
Second Department of Internal Medicine, Institute of Industrial Ecology, University of Occupational and Environmental Health, Kitakyushu, Japan.|Department of Biochemistry, Institute of Industrial Ecology, University of Occupational and Environmental Health, Kitakyushu, Japan.|Craniofacial Developmental Biology and Regeneration Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland.
Yanagihara
Nobuyuki
N
Department of Pharmacology, School of Medicine, Institute of Industrial Ecology, University of Occupational and Environmental Health, Kitakyushu, Japan.
Tanaka
Hiroshi
H
Second Department of Internal Medicine, Institute of Industrial Ecology, University of Occupational and Environmental Health, Kitakyushu, Japan.
Osajima
Akihiko
A
Second Department of Internal Medicine, Institute of Industrial Ecology, University of Occupational and Environmental Health, Kitakyushu, Japan.
Hirano
Takeshi
T
Department of Environmental Oncology, Institute of Industrial Ecology, University of Occupational and Environmental Health, Kitakyushu, Japan.
Higashi
Ken
K
Department of Biochemistry, Institute of Industrial Ecology, University of Occupational and Environmental Health, Kitakyushu, Japan.
Yamada
Kenneth M
KM
Craniofacial Developmental Biology and Regeneration Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland.
Nakashima
Yasuhide
Y
Second Department of Internal Medicine, Institute of Industrial Ecology, University of Occupational and Environmental Health, Kitakyushu, Japan.
Hirano
Hideyasu
H
Department of Biochemistry, Institute of Industrial Ecology, University of Occupational and Environmental Health, Kitakyushu, Japan.
D000818:Animals; D002417:Cattle; D003285:Contractile Proteins; D004247:DNA / Q000096:biosynthesis* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D015870:Gene Expression / Q000187:drug effects; D005920:Glomerular Mesangium / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008840:Microfilament Proteins / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D051304:Profilins; D011493:Protein Kinase C / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000502:physiology*
D003285:Contractile Proteins; D008840:Microfilament Proteins; C495740:Pfn1 protein, rat; D051304:Profilins; D016755:Proto-Oncogene Proteins c-jun; D011956:Receptors, Cell Surface; D018808:Transcription Factor AP-1; D004247:DNA; D011493:Protein Kinase C; D013936:Thymidine