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G protein-coupled receptors control vascular smooth muscle cell proliferation via pp60c-src and p21ras
B Schieffer1, H Drexler, B N Ling
1Division of Cardiology, Hannover Medical School, Germany.
Abstract:
The binding of vasoactive peptides to their respective G protein-coupled receptors has been implicated in the pathogenesis of vascular smooth muscle cell proliferation, leading to the development of hypertension, arteriosclerosis, and restenosis after vascular injury. We previously showed that the cytosolic tyrosine kinase pp60c-src is crucial for angiotensin II (ANG II)-induced activation of the protooncogene p21ras. Therefore, we investigated the role of pp60c-src and p21ras in rat aortic smooth muscle cell proliferation induced by several G protein-coupled receptors. ANG II, endothelin-1, or thrombin increased cell proliferation and DNA synthesis. Electroporation of anti-pp60c-src antibodies into cells abolished proliferation in response to these G protein-coupled receptor ligands but not in response to platelet-derived growth factor-BB (PDGF-BB). In contrast, electroporation of anti-p21ras antibody completely blocked DNA synthesis and cell proliferation in response to ANG II, endothelin-1, thrombin, and PDGF-BB. Our data indicate that the pp60c-src tyrosine kinase is necessary and specific for vascular smooth muscle cell proliferation and DNA synthesis in response to G protein-coupled receptors but not classic growth factor receptors.
Insights
Vasoactive peptides trigger vascular smooth muscle cell proliferation via G protein-coupled receptors. The tyrosine kinase pp60c-src is essential for this process, but not for growth factor-induced proliferation.
Area of Science:
- Cardiovascular Biology
- Cell Signaling
- Molecular Medicine
Background:
- G protein-coupled receptors (GPCRs) mediate responses to vasoactive peptides, contributing to vascular diseases.
- Proto-oncogene p21ras and tyrosine kinase pp60c-src are implicated in angiotensin II (ANG II)-induced vascular cell proliferation.
Purpose of the Study:
- To investigate the roles of pp60c-src and p21ras in rat aortic smooth muscle cell proliferation stimulated by various GPCR ligands.
- To determine the specificity of pp60c-src in GPCR-mediated proliferation compared to growth factor signaling.
Main Methods:
- Rat aortic smooth muscle cells were stimulated with ANG II, endothelin-1, or thrombin.
- Cell proliferation and DNA synthesis were measured.
- Electroporation of anti-pp60c-src and anti-p21ras antibodies was used to inhibit specific proteins.
Main Results:
- ANG II, endothelin-1, and thrombin significantly increased cell proliferation and DNA synthesis.
- Inhibition of pp60c-src abolished proliferation induced by GPCR ligands but not by platelet-derived growth factor-BB (PDGF-BB).
- Inhibition of p21ras blocked proliferation induced by both GPCR ligands and PDGF-BB.
Conclusions:
- pp60c-src tyrosine kinase is specifically required for GPCR-mediated vascular smooth muscle cell proliferation and DNA synthesis.
- p21ras is a common downstream mediator for both GPCR and growth factor signaling pathways in vascular smooth muscle cells.
- These findings highlight distinct signaling mechanisms in vascular cell growth relevant to hypertension and arteriosclerosis.