In patients with multiple sclerosis, there is continuous loss of the insulating myelin sheath that wraps around neurons and increases the speed of impulses in the central nervous system. Whenever neurons are demyelinated, OPCs migrate toward these cells and differentiate into mature, myelin-producing oligodendrocytes, but this process becomes less and less effective as people age.
A nuclear receptor protein called retinoid X receptor gamma (RXR gamma) is known to promote OPC differentiation and remyelination, but, because nuclear receptors generally function in pairs, a team of researchers led by Robin Franklin at the University of Cambridge, UK, set out to identify RXR gamma's binding partners and investigate their possible role in remyelination.
RXR gamma; bound to several nuclear receptors, including VDR, in OPCs and mature oligodendrocytes. Inhibiting VDR impaired OPC differentiation and reduced the cells' ability to remyelinate axons ex vivo. In contrast, Vitamin D, which binds and activates VDR, boosted OPC differentiation.