Apolipoprotein D and platelet-derived growth factor-BB synergism mediates vascular smooth muscle cell migration.
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.
Leung
Wesley C Y
WC
Cardiovascular Research Program, Research Institute, The Hospital for Sick Children, and the Department of Pediatrics, University of Toronto, Canada.
Lawrie
Allan
A
Demaries
Sandra
S
Massaeli
Hamid
H
Burry
Andrea
A
Yablonsky
Shmuel
S
Sarjeant
Jennifer M
JM
Fera
Euridiki
E
Rassart
Eric
E
Pickering
J Geoffrey
JG
Rabinovitch
Marlene
M
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
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