No abstract

Local genomic architecture, such as segmental duplications (SDs), can induce copy number variations (CNVs) hotspots in the human genome, many of which manifest as genomic disorders. Significant technological advances have been achieved for genome-wide CNV investigations, but these costly methods are not suitable for genotyping certain disease-associated CNVs or other loci of interest in populations. Recently, two independent studies showed that the murine meiosis expressed gene 1 (Meig1) was critical to spermatogenesis. We found that the human orthologue MEIG1 is flanked by an SD pair, between which non-allelic homologous recombination (NAHR) can cause recurrent CNVs. To study this potential CNV hotspot and its role in spermatogenesis, we developed a new CNV genotyping method, AccuCopy, based on multiplex competitive amplification to investigate 320 patients with spermatogenic impairment and 93 healthy controls. Three MEIG1 duplications (two in patients and one in controls) were identified, whereas no deletion was found. As NAHR results in more recurrent deletions than duplications at a locus, the over representation of recurrent MEIG1 duplications suggests a potential purifying selection operating on this hotspot, possibly via fecundity. We also showed that AccuCopy is an efficient and reliable method for multiplex CNV genotyping.

Mitochondria-related microRNAs (miRNAs) have recently emerged as key regulators of cell metabolism and can modulate mitochondrial fusion and division. In order to investigate the roles of mitochondria-related miRNAs played in obesity, we conducted comprehensive molecular analysis in vitro and in vivo. Based on high-fat-diet (HFD) induced obese mice, we found that hepatic mitochondrial function was markedly altered. Subsequently, we evaluated the expression levels of selected mitochondria-related miRNAs and found that miR-141-3p was up-regulated strikingly in HFD mice. To further verify the role of miR-141-3p in obesity, we carried out gain-and-loss-of-function study in human HepG2 cells. We found that miR-141-3p could modulate ATP production and induce oxidative stress. Through luciferase report gene assay, we identified that phosphatase and tensin homolog (PTEN) was a target of miR-141-3p. Inhibiting PTEN could alter the mitochondrial function, too. Our study suggested that mitochondria-related miR-141-3p induced mitochondrial dysfunction by inhibiting PTEN.

Mitochondria, acting as the energy metabolism factory, participate in many key biological processes, including the maintenance of sperm viability. Mitochondria-related microRNA (miRNA), encoded by nuclear genome or mitochondrial genome, may play an important regulatory role in the control of mitochondrial function. To investigate the potential role of mitochondria-related miRNAs in asthenozoospermia, we adopted a strategy consisting of initial screening by TaqMan Low Density Array (TLDA) and further validation with quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Validation of the profiling results was conducted in two independent phases. Eventually, two seminal plasma miRNAs (sp-miRs) (miR-101-3p, let-7b-5p) were found to be significantly decreased, while sp-miR-151a-5p was significantly increased in severe asthenozoospermia cases compared with healthy controls. To further study their potential roles in asthenozoospermia, we then evaluated mitochondrial function of GC-2 cells transfected with these potentially functional miRNAs. Our results demonstrated that transfection with miR-151a-5p mimics decreased the mitochondrial respiratory activity. Besides, Adenosine Triphosphate (ATP) level was decreased when transfected with miR-151a-5p mimics. In addition, Cytochrome b (Cytb) mRNA and protein levels were also decreased when miR-151a-5p was overexpressed. These results indicate that miR-151a-5p may participate in the regulation of cellular respiration and ATP production through targeting Cytb.

abstract:The azoospermia factor c (AZFc) region in the long arm of human Y chromosome is characterized by massive palindromes. It harbors eight multi-copy gene families that are expressed exclusively or predominantly in testis. To assess systematically the role of the AZFc region and these eight gene families in spermatogenesis, we conducted a comprehensive molecular analysis (including Y chromosome haplogrouping, AZFc deletion typing and gene copy quantification) in 654 idiopathic infertile men and 781 healthy controls in a Han Chinese population. The b2/b3 partial deletion (including both deletion-only and deletion-duplication) was consistently associated with spermatogenic impairment. In the subjects without partial AZFc deletions, a notable finding was that the frequency of DAZ and/or BPY2 copy number alterations in the infertile group was significantly higher than in the controls. Combined patterns of DAZ and/or BPY2 copy number abnormality were associated with spermatogenic impairment when compared with the pattern of all AZFc genes with common level copies. In addition, in Y chromosome haplogroup O1 (Y-hg O1), the frequency of copy number alterations of all eight gene families was significantly higher in the case group than that in the control group. Our findings indicate that the DAZ, BPY2 genes may be prominent players in spermatogenesis, and genomic rearrangements may be enriched in individuals belonging to Y-hg O1. Our findings emphasize the necessity of routine molecular analysis of AZFc structural variation during the workup of azoospermia and/or oligozoospermia, which may diminish the genetic risk of assisted reproduction.