“Alphabet” Selenoproteins: Implications in Pathology

Selenoproteins are a group of proteins containing selenium in the form of selenocysteine (Sec, U) as the 21st amino acid coded in the genetic code. Their synthesis is dependent on dietary selenium uptake and a common set of cofactors. Selenoproteins accomplish diverse roles in the body and cell processes by acting, for example, as antioxidants, modulators of the immune function, detoxification agents for heavy metals, and other xenobiotics, key compounds in thyroid hormone metabolism. Although the functions of all this protein family are still unknown, several disorders in their structure, activity or expression have been described by researchers. They concluded that selenium or cofactors deficiency, on one hand, or the polymorphism in selenoproteins genes and synthesis, on the other hand, are involved in a large variety of pathological conditions, including type 2 diabetes, cardiovascular, muscular, oncological, hepatic, endocrine, immuno-inflammatory, neurodegenerative diseases. This review is focused on specific roles in medicine only of selenoproteins that are each named after an alphabet letter, less known than the rest of them, regarding their implications in patho-logical processes of several prevalent diseases and also in disease prevention.