Avtor/Urednik		Stroemstedt, Maria; Waterman, Michael R; Haugen, Trine B; Tasken, Kjetil; Parvinen, Martti; Rozman, Damjana
Naslov		Elevated expression of lanosterol 14 alpha-demethylase (CYP51) and the synthesis of oocyte meiosis-activating sterols in postmeiotic germ cells of male rats
Tip		članek
Vir		Endocrinology
Vol. in št.		Letnik 139, št. 5
Leto izdaje		1998
Obseg		str. 2314-21
Jezik		eng
Abstrakt		Mammalian CYP51 encodes lanosterol 14 alpha-demethylase (P45014DM) that is involved in the postsqualene part of cholesterol biosynthesis. This enzyme remove the 14 alpha-methyl group from lanosterol and 24,25-dihydrolanosterol producing intermediates in cholesterol biosynthesis, the oocyte meiosis-activating sterols FF-MAS and MAS-412. Human and rat CYP51 messenger RNAs (mRNAs) are epressed in all tissues, with highest levels inthe testis due to the prsence of an additional shorter CYP51 transcript in this tissue. In sity hybridization shows the highest CYP51 mRNA levels in seminiferous tubules, with only background levels in Leydig cells. The rat testis-specific CYP51 mRNA arises from the use of an uspream polyadenylation site and is restricted to germ cells, being most abudant in elongating spermatids in stages VII-XIV, whereas somatic CYP51 transcripts are present in all cells. In contrast, the mRNA levels of squalene synthase are maximal in round spermatids, and no germ cell-specific transcript is observed. The rat male germ cell-specific CYP51 transcript is translated in vitro to two proteins of approximately 55 and 53.5 kDa. CYP51 activity is higher in protein extracts of testes and germ cells of sexually mature rats than in prepubertal animals, in which postmeiotic germ cells are not yet present. This shows increased capacity for the production of MAS sterols by male germ cells that have already completed meiosis, suggesting that they serve a role different from meiosis activation.
Deskriptorji		CYTOCHROME P-450 GENE EXPRESSION OXIDOREDUCTASES SPERMATOZOA STEROLS RATS LACTATE DEHYDROGENASE MEIOSIS OOCYTES RNA, MESSENGER SQUALENE SYNTHETASE TESTIS TISSUE DISTRIBUTION