Weijun Jiang

Polymorphisms in Protamine 1 and Protamine 2 predict the risk of male infertility: a meta-analysis

Several studies have investigated the association between polymorphisms in protamine 1 and 2 genes and male infertility risk, with inconsistent results to date. This meta-analysis based on the 13 published case-control studies, including 7350 cases and 6167 controls, was performed to further establish the potential association between the 6 common single nucleotide polymorphisms (rs35576928, rs737008, rs35262993, rs2301365, rs1646022, rs2070923) in protamines 1 and 2 and male infertility. The -190C > A (rs2301365) polymorphism was identified as a risk factor for male infertility under all models. Interestingly, rs1646022 and rs737008 polymorphisms exerted protective effects against male sterility in Asian and population-based under some models. No associations between the remaining SNPs and male sterility were observed.

Predictive value of GGN and CAG repeat polymorphisms of androgen receptors in testicular cancer: a meta-analysis

The risk of testicular cancer (TC) is markedly increased in subjects with androgen insensitivity, and previous studies have proposed that GGN and CAG repeats in androgen receptors (AR) could be related to the risk of TC. To evaluate the association between the length of GGN and CAG repeats in AR and TC, a meta-analysis involving 3255 TC cases and 2804 controls was performed. The results suggested that long GGN repeats are associated with an increased risk of TC compared with those < 23 [odds ratio (OR) = 1.22, 95% confidence interval (CI) = 1.05–1.41]; similarly, a subgroup analysis revealed that this association occurred in studies with case sizes > 200, and in the mid-latitude, and seminoma subgroups. The subgroup analysis based on populations, high-latitude, and seminomas/non-seminomas suggested that AR CAG repeat polymorphisms with > 25 and < 21 + > 25 repeats might confer a protective effect to the patients with TC (in the high-latitude subgroup analysis, for > 25 vs. 21–25: OR = 0.54, 95% CI = 0.41–0.70). In contrast, an increased risk of TC was observed for AR CAG repeat polymorphisms with > 25 and < 21 + > 25 repeats in the mid-latitude subgroup (for > 25 vs. 21–25: OR = 1.65, 95% CI = 1.09–2.50). In addition, no associations between the remaining subgroups and male infertility were observed. In short, this meta-analysis suggested that AR GGN and CAG repeat polymorphisms may be involved in the etiology of TC.

Hyperhomocysteinaemia in rats is associated with erectile dysfunction by impairing endothelial nitric oxide synthase activity

To investigate the effect of hyperhomocysteinaemia (HHCy) on penile erectile function in a rat model, a methionine-rich diet was used in which erectile function, the reproductive system, and nitric oxide synthase were characterized. The intracavernous pressure, apomorphine experiments, measurement of oxidative stress, hematoxylin and eosin staining, immunohistochemistry analysis, reverse transcription-polymerase chain reactions and measurement of endothelial nitric oxide synthase activity were utilized. Our results showed that erections in the middle-dose, high-dose, and interference (INF) groups were significantly lower than the control (P < 0.05). INF group, being fed with vitamins B and folic acid, demonstrated markedly improved penile erections compared with the middle-dose group (P < 0.05). HHCy-induced eNOS and phospho-eNOS protein expression was reduced and the antioxidant effect was markedly impaired. The data of the present data provide evidence that HHCy is a vascular risk factor for erectile dysfunction by impairing cavernosa endothelial nitric oxide synthase activity. Intake of vitamins B can alleviate this abnormality.

A novel mutation of MIP in a Chinese family with congenital nuclear cataract identified by whole-exome sequencing

Congenital cataract, a leading cause of visual impairment, is characterized by opacities of the lens, and in most cases occurred at birth or shortly after. Epidemiologic studies on theprevalence of congenital cataract show that roughly 1 to 6 cases/10,000 live births. Up to now, over 60 cataract-associated genes and over 150 other cataract loci have been identified to be responsible for the genetic congenital cataract. Furthermore, different phenotypes may result from same cataract-associated genes and different mutations can result in same phenotypes. In the current study, we identified a novel missense mutation in MIP gene to be responsible for congenital cataracts adopting whole-exome sequencing technology. We used the whole-exome sequencing analysis approach for the recruitment of congenital cataract pedigree. Mutational verification of candidate gene was performed by Sanger sequencing. Sequencing results were analyzed using Chromas 2.41 and the NCBI Genbank database for sequence alignment. To predict the potential effect of the missense mutation on the protein function, we performed the Polyphen-2 program (http://genetics.bwh.harvard.edu/pph2) and Sorting Intolerant from Tolerant (SIFT, http://sift.jcvi. org) program for conservative analysis. Furthermore, clustalx (version 1.83) programapplied to multiple sequence alignment. Compute pI/Mw tool was used to analyze the differences between WT and mutant MIP protein. We used online SWISS-MODEL tool (https://swissmodel.expasy.org/) to compare the wild-type version with the mutant MIP protein. The proband was 15-years-old girl who had a clear diagnosis of autosomal dominant congenital cataract (ADCC). The study adhered to informed consent between Declaration of Helsinki and all participants. A novel substitution mutation c.402G > T (p.E134D) at the exon 2 of the MIP gene was identified in this family (Figure 1), which co-segregated with all affected individuals, whereas the single substitution was detected neither in the unaffected family members nor in 200 racial matched controls. Hence, the p.E134D of human MIP protein was predicted to be “affect protein function” by SIFT and with a score of 0.00. The predictionof Polyphen-2 suggested that p.E134D MIP might be “probably damaging function” with a score of 1.00. Moreover, the MIP missense mutation (c.402G > T, p. E134D) occurred in a highly conserved amino acid. MIP, also known as AQP0, is a lens-structural gene with the length 5150 bp consisting of four exons, the proteomic product of which comprised 263 amino acids. The structure of MIP protein includes six transmembrane bilayerspanning domains (TMD1–TMD6), three extracellular loops (ECL1– ECL3), and two intracellular loops (ICL1–ICL2) and intracellular NH2-terminal and COOH-terminal. According to previous literatures, 17 different mutations of MIP gene have been found to cause the nuclear cataracts. Interestingly, TMD4–TMD45 and COOH-terminal domains are more frequently mutatedcompared to other regions. Nuclear congenital cataract caused by MIP mutations accounts for most significant proportion, especially in China. It is speculated that large population, diverse environmental conditions, and other genetics modifiers lay the foundation for the development of congenital cataract phenotype. There are many types of clinical phenotypes caused by mutations, described as polymorphic, lamellar, nuclear, sutural, punctate, “snail-like” and total cataracts. Although these mutations can result in similar or different phenotypes, obviously the mutations produce different protein dysfunction. MIP, a member of the water-transporting aquaporin family, is the most abundant membrane protein within lens fiber cells and contributes to over 50% of total membrane fiber protein. Research on the MIP mutation with E134G reveals the loss of water permeability function and impaired trafficking, as well as misfolding of the mutant MIP. E134G mutant changed in amino acid hydrostatic charge as well, and caused a distribution of lamellar cataract with sutural opacities. This is a form of lens opacity. In present study, the proband carried E134D associated with nuclear cataract which belongs to a type of formative position of lens opacity. This may impair interaction between MIP protein and several other

Systematic review and meta-analysis of the genetic association between protamine polymorphism and male infertility

While several previous studies have proposed an association between male infertility and protamine polymorphism, the reported findings have shown some inconsistency. To evaluate the potential association between the two most common single nucleotide polymorphisms (rs2301365 and rs1646022) in protamine and male infertility, we performed a meta‐analysis involving 2713 cases and 2086 controls from 15 published case‐controlled studies. Overall, our analysis showed significant associations between the specific protamine single‐nucleotide polymorphism (rs2301365) and male infertility, and this association was indicated by all of the models we tested. Subgroup analysis revealed significant associations with a Caucasian background, PCR sequence, population‐based, case size of > 150 and case size of < 150 subgroups. Similarly, significant associations were found between rs1646022 and male infertility in the hospital population and case size of < 200 subgroups. However, trial sequential analysis showed that the number of patients in the study did not reach optimal information size. Further studies with larger sample sizes are now warranted to clarify the potential roles of the two protamine polymorphisms in the pathogenesis of male infertility. This may help us to understand the precise molecular mechanisms underlying the effect of protamines upon male infertility.

Polymorphisms of protamine genes contribute to male infertility susceptibility in the Chinese Han population

Protamine (PRM) plays important roles in the packaging of DNA within the sperm nucleus. To investigate the role of PRM1/2 and transition protein 1 (TNP1) polymorphisms in male infertility, 636 infertile men and 442 healthy individuals were recruited into this case-controlled study of the Chinese Han population, using MassARRAY technology to analyze genotypes. Our analysis showed that there were no significant differences between controls and infertile cases among the five single nucleotide polymorphisms identified in PRM1, PRM2 and TNP1 [rs737008 (G/A), rs2301365 (C/A), rs2070923 (C/A), rs1646022 (C/G) and rs62180545 (A/G)]. However, we found that the PRM1 and PRM2 haplotypes GCTGC, TCGCA and TCGCC exhibited significant protective effects against male infertility compared to fertile men, while TCGGA, GCTCC and TCGGC represented significant risk factors for spermatogenesis. Our data showed that rs737008 and rs2301365 in PRM1, and rs1646022 in PRM2, were significantly associated with male infertility and that gene–gene interaction played a role in male infertility. A linkage disequilibrium plot for the five SNPs showed that rs737008 was strongly linked with both rs2301365 and rs2070923. These findings are likely to help improve our understanding of the etiology of male infertility. Further studies should include a larger number of genes and SNPs, particularly growing critical genes; such studies will help us to unravel the effect of individual genetic factors upon male infertility.Protamine (PRM) plays important roles in the packaging of DNA within the sperm nucleus. To investigate the role of PRM1/2 and transition protein 1 (TNP1) polymorphisms in male infertility, 636 infertile men and 442 healthy individuals were recruited into this case-controlled study of the Chinese Han population, using MassARRAY technology to analyze genotypes. Our analysis showed that there were no significant differences between controls and infertile cases among the five single nucleotide polymorphisms identified in PRM1, PRM2 and TNP1 [rs737008 (G/A), rs2301365 (C/A), rs2070923 (C/A), rs1646022 (C/G) and rs62180545 (A/G)]. However, we found that the PRM1 and PRM2 haplotypes GCTGC, TCGCA and TCGCC exhibited significant protective effects against male infertility compared to fertile men, while TCGGA, GCTCC and TCGGC represented significant risk factors for spermatogenesis. Our data showed that rs737008 and rs2301365 in PRM1, and rs1646022 in PRM2, were significantly associated with male infertility and that gene-gene interaction played a role in male infertility. A linkage disequilibrium plot for the five SNPs showed that rs737008 was strongly linked with both rs2301365 and rs2070923. These findings are likely to help improve our understanding of the etiology of male infertility. Further studies should include a larger number of genes and SNPs, particularly growing critical genes; such studies will help us to unravel the effect of individual genetic factors upon male infertility.

The P20R mutation of αB-crystallin diminishes its anti-apoptotic activity in human lens epithelial cells

αB-crystallin acts as an anti-apoptosis protein in human lens epithelial (HLE) cells. We recently identified a missense mutation in αB-crystallin that changes proline 20 to an arginine (P20R) in a Chinese family with autosomal dominant congenital posterior polar cataract. The impact of the P20R mutation on the anti-apoptosis function remains unclear. To explore the anti-apoptotic activity of αB-crystallin wild type (αB-wt) and its P20R mutant under oxidative stress, HLE cells were transfected with αB-wt and αB-P20R constructs and expression was measured by western blotting. Flow cytometry and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP digoxigenin nick end-labelling (TUNEL) staining were performed to investigate apoptosis. We found that αB-wt performed a dominant role in inhibiting stress-induced apoptosis, but this function was impeded in cells expressing αB-P20R. The P20R mutant of αB-crystallin exhibits diminished anti-apoptotic activity compared with the native protein.

CAG-repeat polymorphisms in the polymerase γ gene and male infertility: a meta-analysis.

CAG‐repeat in the polymerase γ (POLG) gene encoding polymerase γ for mitochondria is important to spermatogenesis. Compared with a few researchers who raised alteration of CAG‐repeat‐affected male reproductive ability, others did not find the association between CAG‐repeat polymorphisms and male infertility. Therefore, a comprehensive meta‐analysis is necessary to determine the association; 13 case–control studies were screened out using keywords search. From these studies, characteristics were extracted for conducting meta‐analysis. Odds ratio (OR) and 95% confidence interval (CI) were used to describe the results; the results indicated that CAG‐repeat allele was not a risk factor to male infertility (pooled OR = 1.03, 95% CI: 0.79–1.34, P = 0.828). Four different genetic comparisons also demonstrated a negative result: heterozygote comparison (not 10/10 versus 10/10. Pooled OR = 0.99, 95% CI: 0.77–1.27, P = 0.948), homozygote comparison (not 10/not 10 versus 10/10. Pooled OR = 1.08, 95% CI: 0.56–2.06, P = 0.816), the recessive genetic comparison (not 10/not 10 versus not 10/10 + 10/10. Pooled OR = 1.07, 95% CI: 0.58–1.95, P = 0.829) and the dominant genetic comparison (not 10/not 10 + not 10/10 versus 10/10. Pooled OR = 0.97, 95% CI: 0.72–1.29, P = 0.804); based on current researches, this meta‐analysis demonstrated no apparent association between POLG‐CAG‐repeat and male infertility. Similarly, CAG‐repeat was not a sensitive site to male infertility.