Immune system regulator found to protect brain from effects of stroke

A small molecule known to regulate white blood cells has a surprising second role in protecting brain cells from the deleterious effects of stroke, Johns Hopkins researchers report. The molecule, microRNA-223, affects how cells respond to the temporary loss of blood supply brought on by stroke - and thus the cells' likelihood of suffering permanent damage.

''We set out to find a small molecule with very specific effects in the brain, one that could be the target of a future stroke treatment,'' says Valina Dawson, PhD, a professor in the Johns Hopkins University School of Medicine's Institute for Cell Engineering.

''What we found is this molecule involved in immune response, which also acts in complex ways on the brain. This opens up a suite of interesting questions about what microRNA-223 is doing and how, but it also presents a challenge to any therapeutic application,'' Dawson explains.

A report on the discovery was published in the 13 November issue of the Proceedings of the National Academy of Sciences.

RNA is best known as a go-between that shuttles genetic information from DNA and then helps produce proteins based on that information. But, Dawson explains, a decade ago researchers unearthed a completely different class of RNA: small, nimble fragments that regulate protein production. In the case of microRNA, one member of this class, that control comes from the ability to bind to RNA messenger molecules carrying genetic information, and thus prevent them from delivering their messages.

''Compared with most ways of shutting genes off, this one is very quick,'' Dawson notes.