scholarly journals Neuropilin-1 mediates PDGF stimulation of vascular smooth muscle cell migration and signalling via p130Cas

2011 ◽  
Vol 435 (3) ◽  
pp. 609-618 ◽  
Author(s):  
Caroline Pellet-Many ◽  
Paul Frankel ◽  
Ian M. Evans ◽  
Birger Herzog ◽  
Manfred Jünemann-Ramírez ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Tyrosine Phosphorylation ◽  
Muscle Cells ◽  
Immunofluorescent Staining ◽  
Human Coronary Artery ◽  
Neuropilin 1 ◽  
Stimulation Of

NRP1 (neuropilin-1) is a co-receptor for members of the VEGF (vascular endothelial growth factor) family in endothelial cells, but is increasingly implicated in signalling induced by other growth factors. NRP1 is expressed in VSMCs (vascular smooth muscle cells), but its function and the mechanisms involved are poorly understood. The present study aimed to determine the role of NRP1 in the migratory response of HCASMCs (human coronary artery smooth muscle cells) to PDGF (platelet-derived growth factor), and to identify the signalling mechanisms involved. NRP1 is highly expressed in HAoSMCs (human aortic smooth muscle cells) and HCASMCs, and modified in VSMCs by CS (chondroitin sulfate)-rich O-linked glycosylation at Ser612. HCASMC migration induced by PDGF-BB and PDGF-AA was inhibited by NRP1 siRNA (small interfering RNA), and by adenoviral overexpression of an NRP1 mutant lacking the intracellular domain (Ad.NRP1ΔC). NRP1 co-immunoprecipitated with PDGFRα (PDGF receptor α), and immunofluorescent staining indicated that NRP1 and PDGFRα co-localized in VSMCs. NRP1 siRNA also inhibited PDGF-induced PDGFRα activation. NRP1-specific siRNA, Ad.NRP1ΔC and removal of CS glycans using chondroitinase all inhibited PDGF-BB and -AA stimulation of tyrosine phosphorylation of the adapter protein, p130Cas (Cas is Crk-associated substrate), with little effect on other major signalling pathways, and p130Cas knockdown inhibited HCASMC migration. Chemotaxis and p130Cas phosphorylation induced by PDGF were inhibited by chondroitinase, and, additionally, adenoviral expression of a non-glycosylatable NRP1S612A mutant inhibited chemotaxis, but not p130Cas phosphorylation. These results indicate a role for NRP1 and NRP1 glycosylation in mediating PDGF-induced VSMC migration, possibly by acting as a co-receptor for PDGFRα and via selective mobilization of a novel p130Cas tyrosine phosphorylation pathway.

REGULATION OF GROWTH FACTOR PRODUCTION BY ENDOTHELIAL CELLS IN RESPONSE TO COAGULATION AND INFLAMATORY FACTORS

1987 ◽  
Author(s):  
D F Bowen-Pope ◽  
C Gajdusek ◽  
J Harlan ◽  
P Nawroth ◽  
R Ross ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Growth Factor ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Atherosclerotic Lesions ◽  
Cell Biol ◽  
Stimulation Of

Platelet-derived growth factor (PDGF) is a polypeptide growth factor first discovered in, and purified from, human blood platelets. As assayed by its ability to stimulate proliferation of cultured vascular smooth muscle cells, PDGF is the major mitogen in human whole blood serum. PDGF has also been reported to be chemotactic for fibroblasts, vascular smooth muscle cells, and leukocytes, and to be able to stimulate contraction of arterial smooth muscle. This, spectrum of activities suggests that PDGF could play a significant role in several vascular processes, including wound repair and the formation of atherosclerotic lesions (reviewed in Ross et al., 1986 Cell 46:155). Several cell types in addition to the platelet have now been shown to be capable of secreting PDGF-like molecules. In culture, vascular endothelial cells from many sources secrete significant levels of PDGF (DiCorleto and Bowen-Pope, 1983 PNAS 80:1919). Rates of secretion can be increased four fold and more bythe activated procoagulants thrombin (Harlan et al 1986 J. Cell Biol. 103:1129) and factor Xa (Gajdusek et al 1986 J. Cell Biol. 103:419). Thrombin stimulates secretion by the earliest times measurable (about 1.5hr) and this early response is not diminished by inhibitors of protein and RNA synthesis. Nevertheless, unlike secretion from the platelet, stimulated secretion does not represent release of sequestered active PDGF since no reservoir of active PDGF can be detected within the cells prior to stimulation. It is likely therefore that stimulation of secrtion involves the activation or unmasking of an inactive form of PDGF. The proteolytic activities of thrombin and Xa are necessary for activation of secretion but the mechanism does not seem to to involve direct proteolytic activation by thrombin of a precursor since thrombin treatment does not generate active PDGF in freeze-thawed preparations of endothelial cells. We have recently found that tumor necrosis factor alpha (TNF) and gamma interferon (IFN) can stimulate increased rates of secretion of PDGF by cultured human saphenous vein and umbilical vein endothelial cells. Stimulation by a combination of the two is more than additive. In contrast to the rapid kinetics of stimulation by thrombin and Xa, TNF and IFN do not measurably increase secretion for at lease four hrs. This delayed kinetics is paralleled by increases in mRNA encoding the two subunit chains of PDGF ("A" and "B") and it seems likely that in this case stimulation of secretion results from increased rates of mRNA and protein synthesis. Since evidence is accumulating that TNF and IFN are both present in human atherosclerotic lesions, it is possible that they help stimulate production of endothelial cell-derived mitogens, including PDGF and thus contribute to the development of the lesion.

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