Evidence for modulation of genes involved in vascular adaptation by prolonged exposure of endothelial cells to shear stress

Abstract

Objective: Shear stress is known to modulate gene expression. However, the molecular link between blood flow and long-time vessel adaptation is still unclear. In this study, the variations of gene expression by prolonged shear stress exposure was investigated in order to identify genes possibly involved in flow dependent vascular adaptation.

Methods: Human umbilical vein endothelial cells (HUVECs) were exposed to laminar shear stress (6 dyn/cm(2); 24 h) and analyzed by differential display (DDRT-PCR). Flow-modulation of differentially expressed genes by different exposure times (4, 24, 48 h) and in human cardiac microvascular endothelial cells (HCMECs) (24 h exposure) was analyzed by RT-PCR and northern blotting.

Results: DDRT-PCR analysis displayed 13 down- and 20 up-regulated products in response to flow. Four known genes were identified: Angiopoietin-2, a protein reported to reduce vessel stability, was progressively (4-48 h) down-regulated by shear stress. The induction of the anti-angiogenic metalloproteinase METH-1 was maximal after 4 h exposure and sustained over the time (24-48 h). Growth arrest-specific mRNA 3 (gas3) and calpactin 1 light chain (p11) were up-regulated only by prolonged exposure (24-48 h). Analysis of the expression of angiopoietin-2, METH-1, gas3, and p11 in shear stress exposed (24 h) HCMECs showed modulation patterns comparable to those observed in HUVECs.

Conclusion: Since angiopoietin-2 and METH-1 are known to be involved in vessel regression/stabilization, the reported modulation of these genes by prolonged shear stress exposure strongly suggests their participation in flow-dependent vascular adaptation.