Evidence for Rap1 in vascular smooth muscle cells. Regulation of their expression by platelet-derived growth factor BB.
The effect of platelet-derived growth factor (PDGF) on Rap1 expression was investigated in rat vascular smooth muscle cells (SMC). First, evidence for Rap1 proteins was shown by their: (i) detection in membranes using a specific anti-Rap1 antibody, (ii) typical shift in electrophoretic mobility as a consequence of reduction, and (iii) cAMP-induced phosphorylation and immunoprecipitation. Then, the mitogenic activity of 10 ng/ml PDGF AA and BB for 48 h, resulting in a 2- and 5-fold increase in [3H]thymidine incorporation, was correlated with that of total Rap1 protein expression which was found to be 99% +/- 36% and 260% +/- 70%, respectively. Further time-course studies established that this up-regulation of Rap1 proteins was only observed after 48 h of PDGF BB treatment. Lastly, comparative RT-PCR of both rap1a and rap1b mRNAs showed that PDGF BB also up-regulated the rap1a mRNA species, which was 1.5-fold increased in contrast with the rap1b mRNA species. It is concluded that the PDGF BB-induced SMC proliferation is associated with an up-regulation of Rap1a protein.
Quarck
R
R
INSERM U. 348, Hôpital Lariboisière, Paris, France.
Bryckaert
M
M
Magnier
C
C
Corvazier
E
E
Bredoux
R
R
de Gunzburg
J
J
Fontenay
M
M
Tobelem
G
G
Enouf
J
J
D000818:Animals; D000077214:Becaplermin; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D007700:Kinetics; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D020668:rap GTP-Binding Proteins
D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger; D011994:Recombinant Proteins; C075278:platelet-derived growth factor A; D000077214:Becaplermin; D004247:DNA; D019204:GTP-Binding Proteins; D020668:rap GTP-Binding Proteins; D013936:Thymidine