Fig. 4: CYP51A1 is specifically required to convert DHC to DHEA.
From: A bypass gateway from cholesterol to sex steroid biosynthesis circumnavigates CYP17A1
A All 57 CYP enzymes were individually expressed in C4-2 cells, and then the cells were treated with 500 nM DHC. Intracellular DHEA levels were analyzed after 96 h. B Intracellular deuterium-labeled androgen levels from deuterium-labeled DHC (d2-DHC) in control or CYP51A1-overexpressing (OE) C4-2 cells. C Effects on d2-DHEA biosynthesis with or without abiraterone, ASN001, or ketoconazole in CYP51A1 overexpressing 293 T cells. Cells were starved, treated with indicated compounds, and harvested after 5 days. Shown are pathway consequences of abiraterone blockade of 3βHSD1 and ketoconazole blockade of CYP51A1. D In vitro reaction of recombinant human CYP51A1 enzyme with 25 µM DHC. Recombinant CYP51A1, NADPH, and DHC were combined as indicated and incubated at 37 °C for 60 min. DHEA levels were measured by LC-MS/MS. A proposed mechanism is shown. E Steady-state kinetics of CYP51A1 following treatment with DHC (0–100 µM). The estimated kcat is 3.74 ± 0.08 × 10−3 min−1 and Km value of 12.4 ± 0.8 µM for DHC. F CYP51 enzymes from different species were expressed in 293 T cells, which then were treated with 500 nM DHC for 5 days. All steroid measurements were performed using LC-MS/MS and are presented as mean +/− SD. Source data are provided as a Source Data file.
