title: Expression of the vitamin D metabolizing enzyme CYP24A1 at the annulus of human spermatozoa may serve as a novel marker of semen quality.
abstract: Vitamin D (VD) is important for male reproduction in mammals and the VD receptor (VDR) and VD-metabolizing enzymes are expressed in human spermatozoa. The VD-inactivating enzyme CYP24A1 titrates the cellular responsiveness to VD, is transcriptionally regulated by VD, and has a distinct expression at the sperm annulus. Here, we investigated if CYP24A1 expression serves as a marker for VD metabolism in spermatozoa, and whether CYP24A1 expression was associated with semen quality. We included 130 men (53 healthy young volunteers and 77 subfertile men) for semen analysis and immunocytochemical (ICC) detection of CYP24A1. Another 40 men (22 young, 18 subfertile) were tested for in vitro effects of 1,25(OH)(2)D(3) on intracellular calcium concentration ([Ca(2+)](i)) and sperm motility. Double ICC staining showed that CYP24A1 and VDR were either concomitantly expressed or absent in 80% of the spermatozoa from young men. The median number of CYP24A1-expressing spermatozoa was 1% in subfertile men and thus significantly (p < 0.0005) lower than 25% in spermatozoa from young men. Moreover, CYP24A1 expression correlated positively with total sperm count, -concentration, -motility and -morphology (all p < 0.004), and the percentage of CYP24A1-positive spermatozoa increased (15 vs. 41%, p < 0.0005) after percoll-gradient-centrifugation. We noticed that the presence of >3% CYP24A1-positive spermatozoa distinguished young men from subfertile men with a sensitivity of 66.0%, a specificity of 77.9% and a positive predictive value of 98.3%. Functional studies revealed that 1,25(OH)(2)D(3) increased [Ca(2+)](i) and sperm motility in young healthy men, while 1,25(OH)(2)D(3) was unable to increase motility in subfertile patients. In conclusion, we suggest that CYP24A1 expression at the annulus may serve as a novel marker of semen quality and an objective proxy for sperm function.
authors.affiliation: University Department of Growth and Reproduction, Rigshospitalet, Copenhagen, Denmark. mabj@rh.regionh.dk
authors.forename: M
authors.initials: M
authors.lastname: Blomberg Jensen
authors.forename: A
authors.initials: A
authors.lastname: Jørgensen
authors.forename: J E
authors.initials: JE
authors.lastname: Nielsen
authors.forename: P J
authors.initials: PJ
authors.lastname: Bjerrum
authors.forename: M
authors.initials: M
authors.lastname: Skalkam
authors.forename: J H
authors.initials: JH
authors.lastname: Petersen
authors.forename: D L
authors.initials: DL
authors.lastname: Egeberg
authors.forename: S
authors.initials: S
authors.lastname: Bangsbøll
authors.forename: A N
authors.initials: AN
authors.lastname: Andersen
authors.forename: N E
authors.initials: NE
authors.lastname: Skakkebaek
authors.forename: A
authors.initials: A
authors.lastname: Juul
authors.forename: E
authors.initials: E
authors.lastname: Rajpert-De Meyts
authors.forename: S
authors.initials: S
authors.lastname: Dissing
authors.forename: H
authors.initials: H
authors.lastname: Leffers
authors.forename: N
authors.initials: N
authors.lastname: Jørgensen
mesh_terms: D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000096:biosynthesis; D000328:Adult; D015415:Biomarkers; D002118:Calcium; D053493:Cholestanetriol 26-Monooxygenase / Q000096:biosynthesis; D000072467:Cytochrome P450 Family 2; D006801:Humans; D007248:Infertility, Male / Q000175:diagnosis*; D008297:Male; D018167:Receptors, Calcitriol / Q000378:metabolism; D055101:Semen Analysis / Q000379:methods*; D013076:Sperm Count; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000201:enzymology* / Q000378:metabolism; D013250:Steroid Hydroxylases / Q000096:biosynthesis*; D014807:Vitamin D / Q000378:metabolism; D065668:Vitamin D3 24-Hydroxylase; D055815:Young Adult
chemical_list: D015415:Biomarkers; D018167:Receptors, Calcitriol; D014807:Vitamin D; D013250:Steroid Hydroxylases; D000072467:Cytochrome P450 Family 2; C506833:CYP2R1 protein, human; D053493:Cholestanetriol 26-Monooxygenase; C585549:CYP24A1 protein, human; D065668:Vitamin D3 24-Hydroxylase; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase; D002118:Calcium