Molecular study of human sperm RNA: Ropporin and CABYR in asthenozoospermia.

BACKGROUND: Sperm motility is an essential aspect of human fertility. Sperm contain an abundance of transcripts, thought to be remnants of mRNA, which comprise a genetic fingerprint and can be considered a historic record of gene expression during spermatogenesis. The aberrant expression of numerous genes has been found to contribute to impaired sperm motility; these include ROPN1 (rhophilin associated tail protein 1), which encodes a component of the fibrous sheath of the mammalian sperm flagella, and CABYR (calcium-binding tyrosine-(Y)-phosphorylation-regulated protein), which plays an important role in calcium activation and modulation. The aim of this study was to investigate ROPN1 and CABYR gene co-expression in asthenozoospermic semen samples in comparison with normozoospermic samples.

METHODS: We studied 120 semen samples (60 normozoospermic and 60 asthenozoospermic) from Caucasian patients attending our centre for an andrological check-up. Total RNA was extracted from purified spermatozoa with RNeasy mini kit. ROPN1 and CABYR mRNA expression was analysed using RT-qPCR. Continuous variables were described as means ± standard deviations.

RESULTS: ROPN1 and CABYR mRNA were simultaneously downregulated in asthenozoospermic in comparison with normozoospermic samples. There was also a positive correlation between total progressive motility and ROPN1 and CABYR gene expression and between total motile sperm number and ROPN1 and CABYR gene expression.

CONCLUSIONS: The results demonstrated downregulation of both ROPN1 and CABYR in asthenozoospermic samples and importantly, a positive correlation between the expression of the two genes, suggesting that ROPN1 and CABYR co-expression is a prerequisite for normal flagellar function and sperm motility.