RESUMO
Selenoprotein P (Sepp1) is a secreted protein that is made up of 2 domains. The larger N-terminal domain contains 1 selenocysteine residue in a redox motif and the smaller C-terminal domain contains the other 9 selenocysteines. Sepp1 isoforms of varying lengths occur but quantitation of them has not been achieved. Hepatic synthesis of Sepp1 affects whole-body selenium content and the liver is the source of most plasma Sepp1. ApoER2, a member of the lipoprotein receptor family, binds Sepp1 and facilitates its uptake into the testis and retention of its selenium by the brain. Megalin, another lipoprotein receptor, facilitates uptake of filtered Sepp1 into proximal tubule cells of the kidney. Thus, Sepp1 serves in homeostasis and distribution of selenium. Mice with deletion of Sepp1 suffer greater morbidity and mortality from infection with Trypanosoma congolense than do wild-type mice. Mice that express only the N-terminal domain of Sepp1 have the same severity of illness as wild-type mice, indicating that the protective function of Sepp1 against the infection resides in the N-terminal (redox) domain. Thus, Sepp1 has several functions. In addition, plasma Sepp1 concentration falls in selenium deficiency and, therefore, it can be used as an index of selenium nutritional status.
Assuntos
Mamíferos/genética , Selenoproteína P/genética , Selenoproteína P/fisiologia , Animais , Transporte Biológico/genética , Transporte Biológico/fisiologia , Lesões Encefálicas/genética , Lesões Encefálicas/metabolismo , Homeostase/genética , Humanos , Masculino , Mamíferos/metabolismo , Mamíferos/fisiologia , Camundongos , Modelos Biológicos , Doenças Parasitárias/genética , Doenças Parasitárias/metabolismo , Selênio/metabolismo , Selenoproteína P/metabolismo , Espermatogênese/genéticaRESUMO
The enzyme chitotriosidase (ChT), the human analogue of chitinases from non-vertebrate species, is one of the most abundant and indicative proteins secreted by activated macrophages. Its enzymatic activity is elevated in serum of patients suffering from Gaucher's disease type 1 and in some other inherited lysosomal storage disorders, as well as in diseases in which macrophages are activated. The last decade has witnessed the appearance of a substantial number of studies attempting to unravel its cellular functions, which have yet not been fully defined. A great deal of progress has been made in the study of the physiological roles of ChT. This review is looks at the key areas of investigations addressed to further illuminate whether ChT activation might have different functional meanings in various diseases.