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J Cell Physiol. 2007 Mar;210(3):807-18.

Thrombospondin-1 inhibits VEGF levels in the ovary directly by binding and internalization via the low density lipoprotein receptor-related protein-1 (LRP-1).

Author information

1
Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada.

Abstract

VEGF is a potent pro-angiogenic factor whose effects are opposed by a host of anti-angiogenic proteins, including thrombospondin-1 (TSP-1). We have previously shown that VEGF has important extravascular roles in the ovary and that VEGF and TSP-1 are inversely expressed throughout the ovarian cycle. To date, however, a causal interaction between TSP-1 and VEGF has not been identified. Here, we show that TSP-1 has a direct inhibitory effect on VEGF by binding the growth factor and internalizing it via LRP-1. Mice lacking TSP-1 are subfertile and exhibited ovarian hypervascularization and altered ovarian morphology. Treatment of ovarian cells with TSP-1 decreased VEGF levels and rendered the cells more susceptible to TNFalpha-induced apoptosis. Knockdown of TSP-1, through RNA interference, resulted in overexpression of VEGF and reduced cytokine-induced apoptosis. In conclusion, we demonstrate a direct inhibitory effect of TSP-1 on VEGF in the ovary. TSP-1's regulation of VEGF appears to be an important mediator of ovarian angiogenesis and follicle development.

PMID:
17154366
PMCID:
PMC3412056
DOI:
10.1002/jcp.20904
[Indexed for MEDLINE]
Free PMC Article

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