Physiology: Double function at the blood-brain barrier.

Abstract

Two aspects of the blood–brain barrier — the transport of lipids to the brain and the transport of molecules across cells lining blood vessels — have been shown to be regulated by the same protein, Mfsd2a. See Letters p.503 & p.507 The blood–brain barrier serves a vital function in maintaining the necessary environment for brain function but is an inconvenient obstacle to brain-directed therapeutics. Two papers published in this issue of Nature report the involvement of Mfsd2a, a member of the major facilitator superfamily regarded previously as an orphan transporter, in two aspects of blood–brain barrier function. David Silver and colleagues identify Mfsd2a as the major transporter for uptake of the omega fatty acid docosahexaenoic acid (DHA) into the brain. Mfsd2a is exclusively expressed in the endothelium of the blood–brain barrier, and Mfsd2a-knockout mice have reduced levels brain DHA, neuronal loss and reduced brain size and function. Chenghua Gu and colleagues find a role for Mfsd2 as a regulator of blood–brain barrier development and function: the barrier becomes 'leaky' in Mfsd2a-deficient mice, possibly a result of increased transcellular vesicular transport.