Early proto-oncogene expression in rat aortic smooth muscle cells following endothelial removal.
To study the mechanism(s) of vascular smooth muscle cell proliferation in vivo, mRNA levels of c-fos, c-jun, and c-myc were determined by Northern blot analysis following vascular balloon de-endothelialization (BDE). Medial smooth muscle cells (SMC) were separated and studied by enzymatic digestion of the vessel wall. mRNA levels of c-fos and c-jun from aortic smooth muscle cells (SMC) were simultaneously induced within 30 minutes of BDE and declined to baseline by 1.5 hours, c-myc mRNA did not begin to increase until 1 hour after vascular injury. Levels of c-myc peaked at 2 hours and were sustained for an additional 4 hours before gradually declining. Smooth muscle cells derived from enzyme-treated control aortae that did not undergo BDE expressed c-fos and c-jun, but showed no evidence of c-myc message. In contrast, nonenzymatically treated, non-BDE whole aortae (containing both media and adventitia) demonstrated a prominent c-myc signal, but failed to express c-fos and c-jun. Corresponding examination of adventitia derived from enzyme-treated aortae showed this tissue to be a source of all three proto-oncogenes. The results of this study demonstrate the earliest in vivo molecular markers of vascular injury reported to date and implicate SMC proto-oncogene expression in the initiation of SMC proliferation. Furthermore these findings suggest two avenues for proto-oncogene induction, that are due to (1) vessel wall manipulation and (2) humoral stimulation.
Miano
J M
JM
Department of Pathology, New York Medical College, Valhalla 10595.
Tota
R R
RR
Vlasic
N
N
Danishefsky
K J
KJ
Stemerman
M B
MB
D000818:Animals; D001011:Aorta; D002455:Cell Division; D015342:DNA Probes; D004730:Endothelium, Vascular / Q000502:physiology*; D015870:Gene Expression; D008297:Male; D008954:Models, Biological; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D011519:Proto-Oncogenes / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains
D015342:DNA Probes; D012333:RNA, Messenger