Department of Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland.
J Trace Elem Med Biol. 2012 Oct;26(4):262-6. doi: 10.1016/j.jtemb.2012.03.003. Epub 2012 Jun 8.
Selenoprotein P (SeP) is an extracellular protein containing ten selenium atoms in the form of selenocysteine, secreted mainly from the liver. About 60% of the whole plasma selenium level is present in SeP, which makes it a useful biomarker of selenium nutritional status. The main functions of SeP are transport and storage of selenium in plasma. It is especially an important protein for the brain, testes and kidneys where the supplementation of the proper amount of Se ensures the synthesis of selenoenzymes with antioxidant properties.Recently, it has been found that SeP uptake in kidneys, testes and brain depends on the apolipoprotein receptor 2 (ApoER2) and lipoprotein megalin receptor (Lrp2). Megalin receptor represents a physiological SeP receptor in kidneys, mediating the re-uptake of secreted SeP from the primary urine. The absence of a functional megalin receptor causes a significant reduction of plasma selenium and the SeP levels as a result of Se excretion. ApoER2 is a SeP receptor in the brain and testes which uptakes Se from the extracellular fluid. Deletion of ApoER2 in mice leads to a lowered selenium level in the brain and testes, neurological dysfunction, production of abnormal spermatozoa, infertility and even death when the subjects are fed a low-selenium diet.
硒蛋白 P（SeP）是一种含有十个硒原子的细胞外蛋白，以硒代半胱氨酸的形式存在，主要由肝脏分泌。约 60%的全血浆硒水平存在于 SeP 中，这使其成为硒营养状况的有用生物标志物。SeP 的主要功能是在血浆中运输和储存硒。它是大脑、睾丸和肾脏中特别重要的蛋白质，适量补充硒可以确保具有抗氧化特性的硒酶的合成。最近，研究发现肾脏、睾丸和大脑中的 SeP 摄取依赖于载脂蛋白受体 2（ApoER2）和脂蛋白 megalin 受体（Lrp2）。Megalin 受体是肾脏中的生理 SeP 受体，介导从初级尿液中重吸收分泌的 SeP。功能性 megalin 受体缺失会导致血浆硒和 SeP 水平显著降低，这是由于硒的排泄。ApoER2 是大脑和睾丸中的 SeP 受体，从细胞外液中摄取 Se。在小鼠中删除 ApoER2 会导致大脑和睾丸中的硒水平降低、神经功能障碍、产生异常精子、不育甚至在低硒饮食喂养时死亡。
