title: Apolipoprotein D and platelet-derived growth factor-BB synergism mediates vascular smooth muscle cell migration.
abstract: We identified apolipoprotein (apo)D in a search for proteins upregulated in a posttranscriptional manner similar to fibronectin in motile smooth muscle cells (SMCs). To address the function of apoD in SMCs, we cloned a partial apoD cDNA from ovine aortic (Ao) SMCs using RT-PCR. We documented a 2.5-fold increase in apoD protein but no increase in apoD mRNA in Ao SMCs 48 hours after a multiwound migration assay (P<0.01). Confocal microscopy revealed prominent perinuclear and trailing edge expression of apoD in migrating SMCs but not in the confluent monolayer. Stimulation of Ao SMCs with 10 ng/mL platelet-derived growth factor (PDGF)-BB increased apoD protein expression (P<0.05). Moreover, PDGF-BB-stimulated migration of human pulmonary artery SMCs was suppressed by knock-down of apoD using RNAi. Stable overexpression of apoD in Ao SMCs cultured in 10% fetal bovine serum promoted random migration by 62% compared with vector-transfected cells (P<0.01). Overexpression of apoD or addition of exogenous apoD to a rat aortic SMC line (A10) stimulated their migration in response to a subthreshold dose of PDGF-BB (P<0.05). This was unrelated to increased phosphorylation of ERK1/2 or of phospholipase C-gamma1, but correlated with enhanced Rac1 activation. This study shows that apoD can be expressed or taken up by SMCs and can regulate their motility in response to growth factors.
authors.affiliation: Cardiovascular Research Program, Research Institute, The Hospital for Sick Children, and the Department of Pediatrics, University of Toronto, Canada.
authors.forename: Wesley C Y
authors.initials: WC
authors.lastname: Leung
authors.forename: Allan
authors.initials: A
authors.lastname: Lawrie
authors.forename: Sandra
authors.initials: S
authors.lastname: Demaries
authors.forename: Hamid
authors.initials: H
authors.lastname: Massaeli
authors.forename: Andrea
authors.initials: A
authors.lastname: Burry
authors.forename: Shmuel
authors.initials: S
authors.lastname: Yablonsky
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Sarjeant
authors.forename: Euridiki
authors.initials: E
authors.lastname: Fera
authors.forename: Eric
authors.initials: E
authors.lastname: Rassart
authors.forename: J Geoffrey
authors.initials: JG
authors.lastname: Pickering
authors.forename: Marlene
authors.initials: M
authors.lastname: Rabinovitch
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology; D001053:Apolipoproteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology* / Q000502:physiology; D053399:Apolipoproteins D; D000077214:Becaplermin; D002417:Cattle; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics; D004357:Drug Synergism; D004373:Ductus Arteriosus / Q000166:cytology; D004789:Enzyme Activation / Q000187:drug effects; D005312:Fetal Blood / Q000737:chemistry; D006023:Glycoproteins / Q000235:genetics / Q000494:pharmacology* / Q000502:physiology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D026901:Membrane Transport Proteins / Q000235:genetics / Q000494:pharmacology* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D020574:Proto-Oncogene Proteins c-sis; D011651:Pulmonary Artery / Q000166:cytology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000502:physiology; D012756:Sheep; D015398:Signal Transduction; D014162:Transfection; D020830:rac1 GTP-Binding Protein / Q000502:physiology
chemical_list: C024328:APOD protein, human; D001053:Apolipoproteins; D053399:Apolipoproteins D; D016895:Culture Media, Serum-Free; D018076:DNA, Complementary; D006023:Glycoproteins; D026901:Membrane Transport Proteins; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D000077214:Becaplermin; D020830:rac1 GTP-Binding Protein