Purpose
Thrombospondin-1 (TSP-1), which is a matricellular glycoprotein associated with chemotaxis
of vascular smooth muscle cells (VSMCs), is relevant to the development of arterial
lesions. Evidence suggests that TSP-1 receptors are linked to guanosine triphosphate-binding
proteins (G proteins). The purpose of this study was to determine the role of G proteins
in TSP-1–induced VSMC chemotaxis and whether this pathway was associated with extracellular
signal-regulated kinase 1/2 (ERK) or p38 kinase activation (downstream pathways associated
with VSMC chemotaxis).
Methods
In all studies, quiescent VSMCs were preincubated either with serum-free medium, cholera
toxin, pertussis toxin, forskolin, or 3-isobutyl-1-methylxanthine. Using a microchemotaxis
chamber, preincubated VSMCs were exposed to TSP-1 or serum-free medium. Migrated VSMCs
were recorded as cells/5 fields (400×) and analyzed by paired t-test. To evaluate the effect of G proteins on TSP-1–induced ERK or p38 activation,
preincubated VSMCs were exposed to serum-free medium or TSP-1 and analyzed by Western
immunoblotting. For measurement of intracellular cyclic adenosine monophosphate (cAMP)
levels, enzyme-linked immunosorbant assay was performed on preincubated VSMCs exposed
to serum-free medium or TSP-1.
Results
Although pertussis toxin attenuated TSP-1–induced chemotaxis, cholera toxin abolished
TSP-1–induced chemotaxis. Cholera toxin, but not pertussis toxin, inhibited both ERK
and p38 activation. The cAMP stimulators forskolin and IBMX abolished TSP-1–induced
chemotaxis and ERK and p38 activation. Although no changes were observed in cAMP levels
in VSMCs treated with serum-free medium, TSP-1, or pertussis toxin, cholera toxin
alone significantly increased cAMP levels.
Conclusion
Gs protein signaling inhibits TSP-1–induced VSMC chemotaxis by increasing the levels
of cAMP. Gi signaling is involved in the mechanism of TSP-1 stimulated chemotaxis and warrants
additional study. Agents that increase cAMP levels may be beneficial in reducing TSP-1–induced
chemotaxis in response to vascular injury.
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References
- Neovascularization in intimal hyperplasia is associated with vein graft failure after coronary artery bypass surgery.Vasc Med. 2003; 8: 163-167
- VCAM-1 expression precedes macrophage infiltration into subendothelium of vein grafts interposed into carotid arteries in hypercholesterolemic rabbits—a potential role in vein graft atherosclerosis.Atherosclerosis. 2001; 158: 313-319
- Inhibition of complement component C3 reduces vein graft atherosclerosis in apolipoprotein E3-Leiden transgenic mice.Circulation. 2006; 114: 2831-2838
- Thrombospondin-1.Internat J Biochem Cell Biol. 1997; 29: 861-865
- Thrombospondin-1 regulation of smooth muscle cell chemotaxis is extracellular signal-regulated protein kinases 1/2 dependent.Surgery. 1999; 126: 203-207
- Thrombospondin deposition in rat carotid artery injury.Am J Pathol. 1990; 137: 179-185
- Thrombospondin-1 induces activation of focal adhesion kinase in vascular smooth muscle cells.J Vasc Surg. 1999; 29: 1031-1036
- A thrombin-sensitive protein of human platelet membranes.Proc Natl Acad Sci U S A. 1971; 68: 240-243
- Inhibition of phosphatidylinositol 3-kinase and protein kinase C attenuates extracellular matrix protein-induced vascular smooth muscle cell chemotaxis.J Vasc Surg. 2000; 31: 1160-1167
- Diversity of G proteins in signal transduction.Science. 1991; 252: 802-808
- Evolution of the mammalian G protein alpha subunit multigene family.Nat Genet. 1992; 1: 85-91
- Heterotrimeric G proteins in heart disease.Can J Physiol Pharmacol. 2000; 78: 187-198
- G-protein involvement in matrix-mediated motility and invasion of high and low experimental metastatic B16 melanoma clones.Cancer Res. 1989; 49: 5940-5948
- Thrombospondin promotes chemotaxis and haptotaxis of human peripheral blood monocytes.J Immunol. 1994; 153: 4219-4229
- Extracellular matrix proteins are potent agonists of human smooth muscle cell migration.J Vasc Surg. 1996; 24 (discussion 32-3): 25-32
- Neutrophil thrombospondin receptors are linked to GTP-binding proteins.J Cell Physiol. 1996; 168: 217-227
- Strain activation of bovine aortic smooth muscle cell proliferation and alignment: study of strain dependency and the role of protein kinase A and C signaling pathways.J Cell Physiol. 1997; 170: 228-234
- Synergistic inhibition of vascular smooth muscle cell migration by phosphodiesterase 3 and phosphodiesterase 4 inhibitors.Circ Res. 1998; 82: 852-861
- Cyclic GMP-dependent protein kinase regulates vascular smooth muscle cell phenotype.J Vasc Res. 1997; 34: 245-259
- Regulation of human vascular smooth muscle cell migration by beta-adrenergic receptors.Am Surg. 2006; 72: 51-54
- Differential roles of protein kinase C and pertussis toxin-sensitive G-binding proteins in modulation of melanoma cell proliferation and motility by thrombospondin 1.Cancer Res. 1998; 58: 3154-3162
- Integrin-associated protein stimulates alpha2beta1-dependent chemotaxis via Gi-mediated inhibition of adenylate cyclase and extracellular-regulated kinases.J Cell Biol. 1999; 147: 389-400
Article info
Publication history
Accepted:
March 30,
2008
Footnotes
Supported by Grant 9951011T from the American Heart Association and a grant from the Veterans Affairs Merit Review Entry Program.
Identification
Copyright
© 2008 Mosby, Inc. Published by Elsevier Inc. All rights reserved.
