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Pericytes and Vasculature

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II. Pericytes and vasculature

The role of normal vasculature is to provide tissues and organs with blood supply and nutrients. Pericytes are elongated fairly undifferentiated mural cells that line the arterioles and epithelium outside the basement membrane. Endothelial cells shape the lining of the vascular tube, while, mural cells associate with the exterior of the tube. Pericytes are involved in the regulation of blood flow and the transformation of new blood vessels. Typically, pericytes colocalize with capillaries and they play an important role in the process of vascular maturation and stabilization. Classified as either smooth muscle cells or pericytes, mural cells are identified based on the types of vessels they are connected with and what molecular markers they express [1, 2]. It is well known that Regulator of G-protein Signaling 5 (RGS-5) is expressed in pericytes of vessels undergoing angiogenesis. .

In a study that used the growth factor sphingosine-1-phospate (S1P) to stimulate cultured vascular smooth muscle cells, RGS-5 expression was constrained to the leading edge of migrating pericytes. This restriction of RGS-5 greatly reduced cell migration suggesting that RGS-5 may control the inhibitory response of pericytes to growth factors leading to vessel stabilization. Interestingly, the animals in our study carrying a tumor xenograft with induced RGS5 over-expression tended to show a more stable tumor, and had a better survival outcome. In the essential process of pericyte recruitment to endothelial cells during development, RGS5 has shown the ability to regulate PDGFR-β signaling in vitro. This further goes along with the potential role of RGS-5 during pericyte migration. Interestingly, it is known t...

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...es. Physiol Rev, 2011. 91(3): p. 1071-121.

2. Mitchell TS, B.J., Robinson GS, Shima DT, Ng YS., RGS5 expression is a quantitative measure of pericyte coverage of blood vessels. Angiogenesis, 2008. 11(2): p. 141-51.

3. Cho, H., et al., Pericyte-specific expression of Rgs5: implications for PDGF and EDG receptor signaling during vascular maturation. FASEB J, 2003. 17(3): p. 440-2.

4. Tredan, O., et al., Drug resistance and the solid tumor microenvironment. J Natl Cancer Inst, 2007. 99(19): p. 1441-54.

5. Weis, S.M. and D.A. Cheresh, Pathophysiological consequences of VEGF-induced vascular permeability. Nature, 2005. 437(7058): p. 497-504.

6. Silini, A., et al., Regulator of G-protein signaling 5 (RGS5) protein: a novel marker of cancer vasculature elicited and sustained by the tumor's proangiogenic microenvironment. Cell Mol Life Sci, 2012. 69(7): p. 1167-78.
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