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J Steroid Biochem Mol Biol

Title:		Effect of mutations in porcine CYB5A and CYP17A1 on the metabolism of pregnenolone
Author(s):		Squires EJ; Gray MA; Lou Y;
Address:		"Dept. of Animal Biosciences, University of Guelph, Guelph, Ontario, N1G2W1, Canada. Electronic address: jsquires@uoguelph.ca. Dept. of Animal Biosciences, University of Guelph, Guelph, Ontario, N1G2W1, Canada"
Journal Title:		J Steroid Biochem Mol Biol
Year:		2019
Volume:		20190908
Issue:
Page Number:		105469 -
DOI:		10.1016/j.jsbmb.2019.105469
ISSN/ISBN:		1879-1220 (Electronic) 0960-0760 (Linking)
Abstract:		"Cytochrome P450 17A1 (CYP17A1) catalyses the 17alpha-hydroxylation and 17,20 lyase reactions to convert pregnenolone to 17alpha-hydroxypregnenolone (17OHP) and subsequently the androgen dehydroepiandrosterone (DHEA). In pigs and humans, CYP17A1 also catalyses the delta-16-synthase reaction to produce the 16-androstene steroid 5,16-androstadien-3beta-ol (16A), which is then further metabolised to the sex pheromone androstenone. Cytochrome b5A (CYB5A) stimulates the 17,20 lyase reaction and is required for the delta 16-synthase reaction. We have identified and mutated residues in porcine CYP17A1 and CYB5A that may alter the synthesis of DHEA and 16A. This included residues in the steroid binding pocket of CYP17A1 and residues on the surface of CYP17A1 and CYB5A that are involved in binding of CYP17A1 to CYB5A. We then expressed the various mutations of CYB5A and CYP17A1 along with porcine cytochrome P450 oxidoreductase (POR) and cytochrome b5 reductase (CYB5R3) in HEK293 cells and measured the formation of metabolites 16A, 17OHP and DHEA from radiolabelled pregnenolone by high performance liquid chromatography (HPLC). Mutations were identified in both CYP17A1 and CYB5A that affected the production of the different metabolites and also affected the overall production of metabolites. Several combinations of mutations decreased the production of both 16A and DHEA and increased production of 17OHP, while the N62S mutation of CYB5A with wild type CYP17A1 increased production of both 16A and DHEA. The best combination of mutations to reduce the production of 16A, while maintaining the production of DHEA and the overall conversion similar to wild type are the N21K, L28V, N21K/L28V and the R52?ª+M/N62S mutations of CYB5A with the D103S mutation of CYP17A1"
Keywords:		Animals Cytochrome-B(5) Reductase/genetics/metabolism Cytochromes b5/*genetics/metabolism HEK293 Cells Humans Mutation NADPH-Ferrihemoprotein Reductase/genetics/metabolism Pregnenolone/*pharmacology Steroid 17-alpha-Hydroxylase/*genetics/metabolism Swine;
Notes:		"MedlineSquires, E James Gray, Matthew A Lou, Yanping eng Research Support, Non-U.S. Gov't England 2019/09/12 J Steroid Biochem Mol Biol. 2019 Dec; 195:105469. doi: 10.1016/j.jsbmb.2019.105469. Epub 2019 Sep 8"