Bone Abstracts

The essential micronutrient Selenium (Se) plays an important role for bone formation and homeostasis. This notion is mainly derived from animal experimental studies showing impaired bone development and reduced measures of bone quality in animals on diets with low Se supply. Selenoprotein P (SePP) functions as the central Se storage and transport protein. SePP-knockout mice have a growth deficit. SePP is taken up by a receptor-mediated mechanism. We hypothesize that impaired SePP expression affects regular bone development, bone Se status and bone turnover. We have compared gene expression in SePP wild-type, heterozygous and knockout mice. Of the two alleged SePP receptors, only ApoER2 but not megalin was expressed in bone. Notably, ApoER2 expression was inversely associated with SePP levels, indicating that this SePP receptor might be involved in feedback regulation of Se metabolism in bone. When analyzing Se concentrations in bone with total reflection X-ray fluorescence (TXRF), a gender difference became apparent. Male mice appeared more sensitive to differences in SePP-genotype than females. This result supports the notion that SePP represents a Se transporter to bone affecting Se status in a sex-specific way. Our data indicate that bone is a preferentially supplied target tissue of SePP ensuring its high Se concentrations, similar to e.g. brain or endocrine glands, and highlight the importance of selenoproteins for bone physiology.