Related Experiment Videos
Early proto-oncogene expression in rat aortic smooth muscle cells following endothelial removal
Abstract:
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.
Insights
Vascular injury rapidly activates c-fos and c-jun proto-oncogenes in smooth muscle cells. c-myc is later induced, suggesting distinct pathways for smooth muscle cell proliferation following vascular damage.
Area of Science:
- Vascular Biology
- Molecular Biology
- Cell Proliferation
Background:
- Vascular smooth muscle cell (SMC) proliferation is a key factor in vascular diseases.
- Understanding the molecular mechanisms initiating SMC proliferation after injury is crucial.
Purpose of the Study:
- To investigate the in vivo molecular events, specifically proto-oncogene expression, following vascular injury.
- To identify early molecular markers associated with vascular smooth muscle cell proliferation.
Main Methods:
- Vascular balloon de-endothelialization (BDE) model in vivo.
- Northern blot analysis to quantify mRNA levels of c-fos, c-jun, and c-myc.
- Enzymatic digestion to isolate medial smooth muscle cells and adventitia.
Main Results:
- c-fos and c-jun mRNA levels in SMCs were rapidly induced within 30 minutes post-BDE.
- c-myc mRNA induction occurred later, starting at 1 hour and peaking at 2 hours post-injury.
- Adventitia was identified as a source of all three proto-oncogenes (c-fos, c-jun, c-myc).
Conclusions:
- Early proto-oncogene expression (c-fos, c-jun) are the earliest molecular markers of vascular injury reported.
- SMC proto-oncogene expression is implicated in the initiation of vascular smooth muscle cell proliferation.
- Two distinct pathways for proto-oncogene induction exist: vessel wall manipulation and humoral stimulation.