Shear stress modulates the expression of thrombospondin-1 and CD36 in endothelial cells in vitro and during shear stress-induced angiogenesis in vivo.
Binding of thrombospondin-1 (TSP-1) to the CD36 receptor inhibits angiogenesis and induces apoptosis in endothelial cells (EC). Conversely, matrix-bound TSP-1 supports vessel formation. In this study we analyzed the shear stress-dependent expression of TSP-1 and CD36 in endothelial cells in vitro and in vivo to reveal its putative role in the blood flow-induced remodelling of vascular networks. Shear stress was applied to EC using a cone-and-plate apparatus and gene expression was analyzed by RT-PCR, Northern and Western blot. Angiogenesis in skeletal muscles of prazosin-fed (50 mg/l drinking water; 4 d) mice was assessed by measuring capillary-to-fiber (C/F) ratios. Protein expression in whole muscle homogenates (WMH) or BS-1 lectin-enriched EC fractions (ECF) was analyzed by Western blot. Shear stress downregulated TSP-1 and CD36 expression in vitro in a force- and time-dependent manner sustained for at least 72 h and reversible by restoration of no-flow conditions. In vivo, shear stress-driven increase of C/F in prazosin-fed mice was associated with reduced expression of TSP-1 and CD36 in ECF, while TSP-1 expression in WMH was increased. Down-regulation of endothelial TSP-1/CD36 by shear stress suggests a mechanism for inhibition of apoptosis in perfused vessels and pruning in the absence of flow. The increase of extra-endothelial (e.g. matrix-bound) TSP-1 could support a splitting type of vessel growth.
Department of Physiology, Charité Campus Benjamin Franklin--Arnimallee 22, 14195 Berlin, Germany.
M
M
Bongrazio
L
L
Da Silva-Azevedo
E C
EC
Bergmann
O
O
Baum
B
B
Hinz
A R
AR
Pries
A
A
Zakrzewicz
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D018955:CD36 Antigens / Q000096:biosynthesis*; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism* / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000503:physiopathology*; D011224:Prazosin / Q000494:pharmacology; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013314:Stress, Mechanical; D019700:Thrombospondin 1 / Q000096:biosynthesis*; D014158:Transcription, Genetic
D000317:Adrenergic alpha-Antagonists; D018955:CD36 Antigens; D019700:Thrombospondin 1; D012313:RNA; D000469:Alkaline Phosphatase; D011224:Prazosin