====== Smooth muscle actin ======

A study used a variety of techniques to investigate the expression of [[contractile protein]]s in the [[pericyte]]s of the [[CNS]]. The results of [[immunocytochemistry]] on cryosections of brain and retina, retinal whole-mounts and immunoblotting of isolated brain capillaries indicate strong expression of the [[Smooth muscle actin]] (alpha-SM actin) in a significant number of mid-capillary pericytes. Immunogold labelling at the ultrastructural level showed that alpha-SM actin expression in capillaries was exclusive to pericytes, and [[endothelial cell]]s were negative. Compared to alpha-SM actin, non-muscle [[myosin]] was present in lower concentrations. By contrast, smooth muscle myosin isoforms, were absent. Pericytes were strongly positive for the intermediate filament protein [[vimentin]], but lacked [[desmin]] which was consistently found in vascular smooth muscle cells. These results add support for a contractile role in pericytes of the CNS microvasculature, similar to that of vascular smooth muscle cells
((Bandopadhyay R, Orte C, Lawrenson JG, Reid AR, De Silva S, Allt G. Contractile
proteins in pericytes at the blood-brain and blood-retinal barriers. J
Neurocytol. 2001 Jan;30(1):35-44. PubMed PMID: 11577244.
)).