Pro-adhesive and chemotactic activities of thrombospondin-1 for breast carcinoma cells are mediated by alpha3beta1 integrin and regulated by insulin-like growth factor-1 and CD98.
S Chandrasekaran, N H Guo, R G Rodrigues, J Kaiser, D D Roberts
The Journal of biological chemistry
274
11408-16
1999
Show Abstract
Thrombospondin-1 (TSP1) is a matricellular protein that displays both pro- and anti-adhesive activities. Binding to sulfated glycoconjugates mediates most high affinity binding of soluble TSP1 to MDA-MB-435 cells, but attachment and spreading of these cells on immobilized TSP1 is primarily beta1 integrin-dependent. The integrin alpha3beta1 is the major mediator of breast carcinoma cell adhesion and chemotaxis to TSP1. This integrin is partially active in MDA-MB-435 cells but is mostly inactive in MDA-MB-231 and MCF-7 cells, which require beta1 integrin activation to induce spreading on TSP1. Integrin-mediated cell spreading on TSP1 is accompanied by extension of filopodia containing beta1 integrins. TSP1 binding activity of the alpha3beta1 integrin is not stimulated by CD47-binding peptides from TSP1 or by protein kinase C activation, which activate alphavbeta3 integrin function in the same cells. In MDA-MB-231 but not MDA-MB-435 cells, this integrin is activated by pertussis toxin, whereas serum, insulin, insulin-like growth factor-1, and ligation of CD98 increase activity of this integrin in both cell lines. Serum stimulation is accompanied by increased surface expression of CD98, whereas insulin-like growth factor-1 does not increase CD98 expression. Thus, the pro-adhesive activity of TSP1 for breast carcinoma cells is controlled by several signals that regulate activity of the alpha3beta1 integrin. | Immunofluorescence, Flow Cytometry | 10196234
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Enhancement of cell adhesion and spreading by a cartilage-specific noncollagenous protein, cartilage matrix protein (CMP/Matrilin-1), via integrin alpha1beta1
Makihira, S., et al
J Biol Chem, 274:11417-23 (1999)
1999
| Inhibits Activity/Function | 10196235
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Functional regulation of the human integrin VLA-1 (CD49a/CD29) by divalent cations and stimulatory beta 1 antibodies.
Luque, A, et al.
FEBS Lett., 346: 278-84 (1994)
1994
Show Abstract
We have investigated the regulation by divalent cations Mg2+, Ca2+ and Mn2+ of the functional activity of the human integrin VLA-1 expressed on neuroblastoma NB100 cells. VLA-1-mediated adhesion of NB100 cells to ligand collagen type I was supported by either mM concentrations of extracellular Mg2+ or microM levels of Mn2+. In contrast, Ca2+ alone did not induce activation of VLA-1 but exerted a potent inhibitory effect on the Mg(2+)-supported cell adhesion. We have also demonstrated that VLA-1 can be directly activated by the stimulatory monoclonal antibody TS2/16 specific for the integrin beta 1 subunit, resulting in effective adhesion of NB100 cells to type I collagen. This study has been possible by using a novel blocking VLA-alpha 1 specific monoclonal antibody, 5E8D9. | | 7516898
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