Department of Public Health and Pediatric Sciences, University of Turin, Turin, Italy.
Obstetrics and Gynecology 1U, Physiopathology of Reproduction and IVF Unit, Department of Surgical Sciences, S. Anna Hospital, University of Turin, Turin, Italy.
Mol Biol Rep. 2021 Jul;48(7):5803-5808. doi: 10.1007/s11033-021-06577-6. Epub 2021 Jul 23.
Human endogenous retroviruses (HERVs), remnants of ancestral infections, represent 8% of the human genome. HERVs are co-opted for important physiological functions during embryogenesis; however, little is known about their expression in human gametes. We evaluated the transcriptional levels of several retroviral sequences in human spermatozoa.
We assessed, through a Real-Time PCR assay, the transcription levels of the pol genes of HERV-H, -K and -W families and of env genes of syncytin (Syn)1 and Syn2 in the spermatozoa from 8 normospermic subjects. The entity and distribution of their expressions were compared to values found in white blood cells (WBCs) from 16 healthy volunteers. The level of HERV transcripts was significantly lower in spermatozoa than in WBCs for HERV-H-pol, HERV-K-pol, HERV-W-pol, and Syn2.In contrast, the level of expression of Syn1 in the sperm was similar to that found in WBCs and it was significantly higher than the mRNA concentrations of other HERV genes in spermatozoa.
Our findings show, for the first time, the presence of several retroviral mRNAs in the sperm, although in low amounts. The higher concentration of Syn1 suggests that it could play a key role in the fusion process between gametes during fertilization and, perhaps, be involved in embryo development. Further studies could clarify whether aberrant HERV expressions, in particular of Syn1, negatively affect fertilization and embryo growth and whether sperm manipulation procedures, such as cryopreservation, may potentially influence HERV transcription in the human male gamete.
人类内源性逆转录病毒（HERV）是祖先感染的残余物，占人类基因组的 8%。HERV 在胚胎发生过程中被篡夺用于重要的生理功能；然而，对于它们在人类配子中的表达知之甚少。我们评估了几种逆转录病毒序列在人类精子中的转录水平。
我们通过实时 PCR 测定评估了 8 名正常精子供体精子中 HERV-H、-K 和 -W 家族的 pol 基因和 Syncytin（Syn）1 和 Syn2 的 env 基因的转录水平。它们的表达的实体和分布与 16 名健康志愿者的白细胞（WBC）中的值进行了比较。与 WBC 相比，HERV-H-pol、HERV-K-pol、HERV-W-pol 和 Syn2 在精子中的 HERV 转录物水平显着降低。相比之下，Syn1 在精子中的表达水平与在 WBC 中发现的水平相似，并且显着高于精子中其他 HERV 基因的 mRNA 浓度。
我们的研究结果首次表明，尽管数量较少，但精子中存在几种逆转录病毒 mRNA。Syn1 的浓度较高表明它可能在受精过程中配子融合过程中发挥关键作用，并且可能参与胚胎发育。进一步的研究可以阐明异常 HERV 表达，特别是 Syn1，是否会对受精和胚胎生长产生负面影响，以及精子处理程序（如冷冻保存）是否可能影响人类精子中的 HERV 转录。
