Naslov
CYP51 and spermatogenesis in rodent testis

Autori
Cotman, M. ; Frangež, R. ; Ježek, Davor ; Banek, Ljerka ; Rozman, Damjana

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Proceedings / 6th Multinational Congress on Microscopy-European Extension / Milat, Ognjen ; Ježek, Davor - Zagreb : Hrvatsko mikroskopijsko društvo, 2003, 49-50

Skup
6th Multinational Congress on Microscopy

Mjesto i datum
Pula, Hrvatska, 01.06.2003. - 05.06.2003

Vrsta sudjelovanja
Plenarno

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
CYP51; MAS; testis; rodent

Sažetak
Lanosterol 14a-demethylase (CYPS1) is a cytochrome P450 enzyme involved in the postqualene portion of cholesterol biosynthesis. In the presence of the cytochrome P450 reductase, CYPS 1 removes 14a-methyl group from lanosterol forming FFMAS (folicular Iluid meiosis activating sterol). In somatic cells FF-MAS and T-MAS (testis meiosis activating sterol), the product of the sterol 014-reductase, are intermediates in biosynthesis of cholesterol, while in germ cells they acumulate. FFMAS and T-MAS stimulate the reinitiation of meiosis in mouse oocyte in vitro and are belived to have important roles in fertilisation. Mammalian CYPS1 protein is believed to be expressed in all cell types where it is located primarily on the endoplasmatic reiculum (ER). Many endoplasmic reticulum resident protein are transported from the ER and then retrived. Using confocal laser microscopy and electron microscopy we found the complete lanosterol 14a-demethylase system (CYPS1 and its redox partner NADPH-P450 reductase) located on acrosomal membranes where it remains stabilized for several days during sperm maturation phases. Modifcations of the CYPS1 protein take place after the protein exits the testis. It is speculated that acrosomal localization of the lanosterol 14a-demethylase system is not a mis-sorting event, but rather a physiological event, allowing mature male germ cells to retain the meiosis activating sterol-synthesis capacity. This work also reveals unique trafficking of a cytochrome P450 enzyme from the smooth endoplasmic reticulum, trough the Golgi apparatus, to a specialized organele acrosome. In the mouse liver CYPS1 resides primarily on membranes of the smooth endoplasmic reticulum (SER). Significant amount of the protein is detected also in cytoplasmic organelles. It is detected also on acrosomal membrane from ejaculated sperm of bull and sheep, indicting evolutionarily conserved mechanism for its longterm storage/stabilization. The expected 53 kDa immunoreactive CYPS1 predominates in the liver microsomes, however on cis- , medial- and trans- Golgi 70 kDa form is found. In mouse starved for 24 hours the 70 kDa form disappered, however, the 53 kDa form remained present. Acrosomal membranes isolated from ram and bull sperm contain 50 kDa, 60 kDa, 70 kDa, 90 kDa and 120 kDa CYPS1immunoreactive proteins that are detected with different intensity in different preparations. Both 70 kDa immunoreactive CYPS1 proteins, from mouse liver Golgi fractions as well as from ram and bull acrosome, are likely formed in the Golgi. The 70-kDa CYPS1 immunoreactive protein is likely not ubiquinated but seems to be glycosilated. These data show for the first time that cell type-specific mechanisms and posttranslational modifications may influence trafficking of cytochrome P450 proteins. CYPS 1 is the flrst cytochrome P450 to be detected on the acrosomal membrane.

Izvorni jezik
Engleski

Znanstvena područja
Kliničke medicinske znanosti

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