More roles for selenoprotein P: local selenium storage and recycling protein in the brain.

How is the essential micronutrient, selenium (Se), transported in the serum and then donated to tissues? In this issue of the Biochemical Journal, Schweizer and colleagues demonstrate, using conditional and total mouse knockout models, that SePP (selenoprotein P) is the major transporter of Se in the serum. Moreover, in the sanctuary area of the brain, SePP was shown to play a hitherto unexpected role as a local Se storage and recycling protein that directly maintains brain Se levels. Considering the function of Se in normal brain metabolism, these results are crucial for our understanding of the role of selenoproteins in redox regulation, antioxidant defences, thyroid hormone metabolism and the development of neurodegenerative conditions.