John Libbey Eurotext

Hématologie

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Thrombospondins : a family of glycoproteins involved in cell adhesive interactions Volume 1, issue 6, Novembre - Décembre 1995

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NSERM U. 353 « Protéines adhésives et protéases des cellules vasculaires et sanguines », Institut d'Hématologie, 1, avenue Claude- Vellefaux, 75010 Paris.

Thrombospondin (TSP-1, Mr = 450 000) is secreted from platelets upon activation and plays a major role in hemostasis by promoting the secretion-dependent phase of platelet aggregation. TSP-1 is also implicated in mediating the interaction between monocytes or tumor cells and activated platelets, and promotes the adherence of tumor cells and pathological erythrocytes to the endothelium. TSP-1 is synthesized and secreted by a variety of epithelial and mesenchymal cells and participates in a number of processes by modulating cell adhesion, migration and proliferation. Its expression by vascular cells is regulated by cytokines and hormones and appears to correlate with physiopathological states such as tissue repair and atherosclerosis. TSP-1 is considered as a negative regulator of tumor angiogenesis whose synthesis is controlled by tumor suppressor genes. It is now known that thrombospondin comprises a family of at least five homologous proteins, encoded by distinct genes, which appear to differ in their distribution during embryogenesis and in adult tissues. Structural differences suggest that each protein may subserve a discrete function.