ABSTRACT
Cysteine-rich secretory protein 2 (CRISP2) is an important protein in spermatozoa that plays roles in modulating sperm flagellar motility, the acrosome reaction, and gamete fusion. Spermatozoa lacking CRISP2 exhibit low sperm motility and abnormal morphology. However, the molecular mechanisms underlying the reduction of CRISP2 in asthenoteratozoospermia (ATZ) remain unknown. In this study, low expression of CRISP2 protein rather than its mRNA was observed in the ejaculated spermatozoa from ATZ patients as compared with normozoospermic males. Subsequently, bioinformatic prediction, luciferase reporter assays, and microRNA-27a (MIR-27a) transfection experiments revealed that MIR-27a specifically targets CRISP2 by binding to its 3' untranslated region (3'-UTR), suppressing CRISP2 expression posttranscriptionally. Further evidence was provided by the clinical observation of high MIR-27a expression in ejaculated spermatozoa from ATZ patients and a negative correlation between MIR-27a expression and CRISP2 protein expression. Finally, a retrospective follow-up study supported that both high MIR-27a expression and low CRISP2 protein expression were associated with low progressive sperm motility, abnormal morphology, and infertility. This study demonstrates a novel mechanism responsible for reduced CRISP2 expression in ATZ, which may offer a potential therapeutic target for treating male infertility, or for male contraception.
ABSTRACT
Objective To study sperm mRNA transcript expression of CRISP2 gene in the semen of patients with different types of spermatogenetic failure. Methods A total of 150 male infertility patients were divided into normal group, asthenozoospermia group and oligozoospermia group(n=50 for each group). Total RNA was extracted from sperm cells. Re-al-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) method was used to detect CRISP 2 gene mRNA levels in three groups. Results There was a significantly higher expression of CRISP2 in normal group (10.281 ± 2.173) than that of asthenozoospermia group (2.092±0.969, P＜0.05). There was no significant difference in the expression of CRISP2 between normal group and oligozoospermia group (9.420±2.794, P>0.05). The relative expression of CRISP2 was sig-nificantly lower in asthenozoospermia group than that of oligozoospermia group (P＜0.05). Conclusion The CRISP2 expres-sion was significantly different in patients with different types of spermatogenic failure. The reduced expression of CRISP 2 may lead to the decreased sperm motility.