Gholinezhad Maryam, Yousefnia-Pasha Yousefreza, Hosseinzadeh Colagar Abasalt, Mohammadoo-Khorasani Milad, Bidmeshkipour Ali
Department of Biology, Faculty of Basic Sciences, Razi University, Kermanshah, Iran.
Infertility and Reproductive Health Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran.
J Cell Biochem. 2019 Feb;120(2):1958-1968. doi: 10.1002/jcb.27492. Epub 2018 Sep 11.
Mitochondria play a crucial role in energy metabolism for the survival and motility of sperm during fertilization. The aim of this study was to determine the association of large-scale mitochondrial DNA deletions with abnormal sperm motility and morphology in asthenoteratozoospermic patients.
In this case-control study, 41 semen samples were collected from 18 normozoospermic healthy men and 23 asthenoteratozoospermic patients, according to the WHO guidelines. The swim-up technique was used for separation of spermatozoa on the basis of their motility. Long-range polymerase chain reaction (PCR) was used for screening of mitochondrial DNA (mtDNA) large-scale deletions, and primer shift PCR was used for confirmation of deletions.
The mean sperm motility, normal morphology, and progressive motility in asthenoteratozoospermic patients were significantly lower than in the normozoospermic group (P < 0.0001). There was a positive significant correlation between motility and normal sperm morphology ( P < 0.0001, r = 0.741). The results of long-range PCR revealed the existence of 4866-bp deletion along with the two common 4977-bp and 7436-bp deleted mtDNA in both groups. However, the frequency of multiple mtDNA deletions in the asthenoteratozoospermic group (15/23, 65.22%) was significantly higher than that in the normozoospermic group (7/18, 38.89%). Direct sequencing of the 534-bp PCR product revealed that it was amplified from the mtDNA with a 4866-bp deletion flanked by a seven-nucleotide direct repeat (5'-ACCCCCT-3').
Our findings suggested that these large-scale deletions of mtDNA may be genetic risk factors for poor sperm quality in asthenoteratozoospermia-induced male infertility. Thus, it is necessary to understand the mechanisms behind the generation of these deletions.
线粒体在受精过程中精子的存活和运动所需的能量代谢中起着关键作用。本研究的目的是确定在弱畸精子症患者中，大规模线粒体DNA缺失与精子运动异常和形态异常之间的关联。
在本病例对照研究中，根据世界卫生组织指南，从18名精子正常的健康男性和23名弱畸精子症患者中收集了41份精液样本。采用上游泳动技术根据精子活力分离精子。使用长距离聚合酶链反应（PCR）筛选线粒体DNA（mtDNA）大规模缺失，并使用引物移位PCR确认缺失。
弱畸精子症患者的平均精子活力、正常形态和进行性活力显著低于精子正常组（P < 0.0001）。活力与正常精子形态之间存在显著正相关（P < 0.0001，r = 0.741）。长距离PCR结果显示，两组均存在4866 bp缺失以及两种常见的4977 bp和7436 bp缺失的mtDNA。然而，弱畸精子症组中多个mtDNA缺失的频率（15/23，65.22%）显著高于精子正常组（7/18，38.89%）。对534 bp PCR产物的直接测序显示，它是从mtDNA扩增而来，该mtDNA有一个4866 bp缺失，两侧为七核苷酸直接重复序列（5'-ACCCCCT-3'）。
我们的研究结果表明，这些mtDNA的大规模缺失可能是弱畸精子症所致男性不育中精子质量差的遗传危险因素。因此，有必要了解这些缺失产生背后的机制。
