Functional characterization of mutant CYP17 genes isolated from a 17 alpha-hydroxylase/17,20-lyase-deficient patient.
CYP17 has a dual enzymatic activity that is necessary for steroid hormone biosynthesis. It catalyzes the 17 alpha-hydroxylation of progesterone or pregnenolone and also removes an acetyl moiety of hydroxy-progesterone or hydroxypregnenolone by its 17,20-lyase activity to produce androstenedione or dehydroepiandrosterone (DHEA), respectively. We previously isolated a compound heterozygous mutant of CYP17 from a Korean female patient: 1-base deletion and 1-base transversion mutation at 1 allele and 3-base deletion mutation at the other allele. Here we tested the functional activities of these 2 mutant CYP17 alleles using a transfection analysis in COS-1 cells with radiolabeled substrates and thin layer chromatography. Both mutant CYP17 genes lost not only 17 alpha-hydroxylation activity, but also 17,20-lyase activity in this assay system. This nonfunctional nature of 2 mutant CYP17 genes explains the clinical manifestation of a patient who had 17 alpha-hydroxylase deficiency.
Hahm
Jong Ryeal
JR
Department of Internal Medicine, College of Medicine and Gyeongsang Institute of Health Science, Gyeongsang National University, JinJu 660-751, Korea.
Jung
Tae Sik
TS
Byun
Sook Yong
SY
Lee
Young Nam
YN
Lee
Kon Ho
KH
Kim
Deok Ryong
DR
D000312:Adrenal Hyperplasia, Congenital / Q000201:enzymology / Q000235:genetics*; D000483:Alleles; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D005260:Female; D017353:Gene Deletion; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D006900:Hydroxylation; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000235:genetics; D011374:Progesterone / Q000031:analogs & derivatives / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics* / Q000502:physiology*; D014162:Transfection; D014316:Tritium
D012333:RNA, Messenger; D011994:Recombinant Proteins; D014316:Tritium; D011374:Progesterone; D013254:Steroid 17-alpha-Hydroxylase