Is BRD7 associated with spermatogenesis impairment and male infertility in humans? A case-control study in a Han Chinese population

A comprehensive study of common and rare genetic variants in spermatogenesis-related loci identifies new risk factors for idiopathic severe spermatogenic failure

STUDY QUESTION

Can genome-wide genotyping data be analysed using a hypothesis-driven approach to enhance the understanding of the genetic basis of severe spermatogenic failure (SPGF) in male infertility?

SUMMARY ANSWER

Our findings revealed a significant association between SPGF and the SHOC1 gene and identified three novel genes (PCSK4, AP3B1, and DLK1) along with 32 potentially pathogenic rare variants in 30 genes that contribute to this condition.

WHAT IS KNOWN ALREADY

SPGF is a major cause of male infertility, often with an unknown aetiology. SPGF can be due to either multifactorial causes, including both common genetic variants in multiple genes and environmental factors, or highly damaging rare variants. Next-generation sequencing methods are useful for identifying rare mutations that explain monogenic forms of SPGF. Genome-wide association studies (GWASs) have become essential approaches for deciphering the intricate genetic landscape of complex diseases, offering a cost-effective and rapid means to genotype millions of genetic variants. Novel methods have demonstrated that GWAS datasets can be used to infer rare coding variants that are causal for male infertility phenotypes. However, this approach has not been previously applied to characterize the genetic component of a whole case-control cohort.

STUDY DESIGN SIZE DURATION

We employed a hypothesis-driven approach focusing on all genetic variation identified, using a GWAS platform and subsequent genotype imputation, encompassing over 20 million polymorphisms and a total of 1571 SPGF patients and 2431 controls. Both common (minor allele frequency, MAF > 0.01) and rare (MAF < 0.01) variants were investigated within a total of 1797 loci with a reported role in spermatogenesis. This gene panel was meticulously assembled through comprehensive searches in the literature and various databases focused on male infertility genetics.

PARTICIPANTS/MATERIALS SETTING METHODS

This study involved a European cohort using previously and newly generated data. Our analysis consisted of three independent methods: (i) variant-wise association analyses using logistic regression models, (ii) gene-wise association analyses using combined multivariate and collapsing burden tests, and (iii) identification and characterisation of highly damaging rare coding variants showing homozygosity only in SPGF patients.

MAIN RESULTS AND THE ROLE OF CHANCE

The variant-wise analyses revealed an association between SPGF and SHOC1-rs12347237 (P = 4.15E-06, odds ratio = 2.66), which was likely explained by an altered binding affinity of key transcription factors in regulatory regions and the disruptive effect of coding variants within the gene. Three additional genes (PCSK4, AP3B1, and DLK1) were identified as novel relevant players in human male infertility using the gene-wise burden test approach (P < 5.56E-04). Furthermore, we linked a total of 32 potentially pathogenic and recessive coding variants of the selected genes to 35 different cases.

LARGE SCALE DATA

Publicly available via GWAS catalog (accession number: GCST90239721).

LIMITATIONS REASONS FOR CAUTION

The analysis of low-frequency variants presents challenges in achieving sufficient statistical power to detect genetic associations. Consequently, independent studies with larger sample sizes are essential to replicate our results. Additionally, the specific roles of the identified variants in the pathogenic mechanisms of SPGF should be assessed through functional experiments.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings highlight the benefit of using GWAS genotyping to screen for both common and rare variants potentially implicated in idiopathic cases of SPGF, whether due to complex or monogenic causes. The discovery of novel genetic risk factors for SPGF and the elucidation of the underlying genetic causes provide new perspectives for personalized medicine and reproductive counselling.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by the Spanish Ministry of Science and Innovation through the Spanish National Plan for Scientific and Technical Research and Innovation (PID2020-120157RB-I00) and the Andalusian Government through the research projects of 'Plan Andaluz de Investigación, Desarrollo e Innovación (PAIDI 2020)' (ref. PY20_00212) and 'Proyectos de Investigación aplicada FEDER-UGR 2023' (ref. C-CTS-273-UGR23). S.G.-M. was funded by the previously mentioned projects (ref. PY20_00212 and PID2020-120157RB-I00). A.G.-J. was funded by MCIN/AEI/10.13039/501100011033 and FSE 'El FSE invierte en tu futuro' (grant ref. FPU20/02926). IPATIMUP integrates the i3S Research Unit, which is partially supported by the Portuguese Foundation for Science and Technology (FCT), financed by the European Social Funds (COMPETE-FEDER) and National Funds (projects PEstC/SAU/LA0003/2013 and POCI-01-0145-FEDER-007274). S.S. is supported by FCT funds (10.54499/DL57/2016/CP1363/CT0019), ToxOmics-Centre for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, and is also partially supported by the Portuguese Foundation for Science and Technology (UIDP/00009/2020 and UIDB/00009/2020). S. Larriba received support from Instituto de Salud Carlos III (grant: DTS18/00101), co-funded by FEDER funds/European Regional Development Fund (ERDF)-a way to build Europe) and from 'Generalitat de Catalunya' (grant 2021SGR052). S. Larriba is also sponsored by the 'Researchers Consolidation Program' from the SNS-Dpt. Salut Generalitat de Catalunya (Exp. CES09/020). All authors declare no conflict of interest related to this study.

BRD7 facilitates ferroptosis via modulating clusterin promoter hypermethylation and suppressing AMPK signaling in diabetes-induced testicular damage

BACKGROUND

Diabetes mellitus (DM)-induced testicular damage is associated with sexual dysfunction and male infertility in DM patients. However, the pathogenesis of DM-induced testicular damage remains largely undefined.

METHODS

A streptozotocin (STZ)-induced diabetic model and high glucose (HG)-treated in vitro diabetic model were established. The histological changes of testes were assessed by H&E staining. Serum testosterone, iron, MDA and GSH levels were detected using commercial kits. Cell viability and lipid peroxidation was monitored by MTT assay and BODIPY 581/591 C11 staining, respectively. qRT-PCR, immunohistochemistry (IHC) or Western blotting were employed to detect the levels of BRD7, Clusterin, EZH2 and AMPK signaling molecules. The associations among BRD7, EZH2 and DNMT3a were detected by co-IP, and the transcriptional regulation of Clusterin was monitored by methylation-specific PCR (MSP) and ChIP assay.

RESULTS

Ferroptosis was associated with DM-induced testicular damage in STZ mice and HG-treated GC-1spg cells, and this was accompanied with the upregulation of BRD7. Knockdown of BRD7 suppressed HG-induced ferroptosis, as well as HG-induced Clusterin promoter methylation and HG-inactivated AMPK signaling in GC-1spg cells. Mechanistical studies revealed that BRD7 directly bound to EZH2 and regulated Clusterin promoter methylation via recruiting DNMT3a. Knockdown of Clusterin or inactivation of AMPK signaling reverses BRD7 silencing-suppressed ferroptosis in GC-1spg cells. In vivo findings showed that lack of BRD7 protected against diabetes-induced testicular damage and ferroptosis via increasing Clusterin expression and activating AMPK signaling.

CONCLUSION

BRD7 suppressed Clusterin expression via modulating Clusterin promoter hypermethylation in an EZH2 dependent manner, thereby suppressing AMPK signaling to facilitate ferroptosis and induce diabetes-associated testicular damage.

Genetic Variations in Metallothionein Genes and Susceptibility to Hypertensive Disorders of Pregnancy: A Case-Control Study

Background: The involvement of oxidative stress in the pathological process of hypertensive disorders of pregnancy (HDP) gives rise to the interest in exploring the association of genetic variations in antioxidant metallothionein (MT) genes with HDP susceptibility.

Methods: Seventeen single-nucleotide polymorphisms(SNPs) in MT genes were selected to conduct genotyping based on a case-control study consisting of 371 HDP cases (pregnancy with chronic hypertension (66), gestational hypertension (172), and preeclampsia or preeclampsia superimposed on chronic hypertension (133)) and 479 controls. The association between SNPs in MTs and the risk of HDP was estimated with unconditional logistic regression analysis and further tested with the false-positive report probability (FPRP) procedure. The joint effects of SNPs on the HDP risk were assessed by haplotype analysis.

Results: After the adjustment for age and pre-pregnancy body mass index (pre-BMI) in the logistic regress analysis and followed by the FPRP test, the genetic variation rs10636 (OR = 0.46, 95% CI: 0.30–0.71 for GG vs. CC, p = 0.000 and OR = 0.48, 95% CI: 0.32–0.73 for GG vs. CG/CC, p = 0.001) in MT2A was associated with gestational hypertension. Other four SNPs, that is, rs11076161 (OR = 1.89, 95% CI: 1.35–2.63 for GG vs. GA/AA, p = 0.000) in MT1A; rs7191779 (OR = 1.54, 95% CI: 1.11–2.13 for CC vs. CG/GG, p = 0.010) in MT1B; rs8044719 (OR = 0.57, 95% CI: 0.40–0.80 for GT vs. GG, p = 0.001) in MT1DP; and rs8052334 (OR = 1.52, 95% CI: 1.10–2.11 for TT vs. TC/CC, p = 0.012) in MT1B were significantly associated with the susceptibility of HDP. The haplotype analysis among 11, 10, 10, and seven SNPs in MT (MT1A, MT2A, MT1M, MT1B, and MT1DP) genes showed that eight (A-C-G-T-C-G-A-G-C-G-C, OR = 4.559; A-C-T-C-C-C-A-G-C-G-C, OR = 5.777; A-C-T-T-C-G-A-G-C-G-C, OR = 4.590; G-A-T-C-C-G-C-G-G-C-C, OR = 4.065; G-A-T-C-G-C-C-G-G-C-C, OR = 4.652; G-A-T-T-C-C-C-G-G-C-C, OR = 0.404; G-C-T-C-C-C-A-G-G-C-C, OR = 1.901; G-C-T-T-C-C-A-G-G-C-C, and OR = 3.810), five (C-G-A-T-C-A-C-C-G-G, OR = 2.032; C-G-A-T-C-G-C-C-G-G, OR = 2.077; G-A-C-T-C-A-C-C-T-G, OR = 0.564; G-G-A-G-C-A-C-C-G-G, OR = 5.466; G-G-A-T-T-A-G-C-G-G, and OR = 0.284), five (A-C-G-T-C-G-A-G-C-C, OR = 2.399; A-C-T-C-C-C-C-T-G-G, OR = 0.259; G-A-T-C-C-C-C-G-G-C, OR = 1.572; G-A-T-C-G-C-C-G-G-C, OR = 0.001; G-C-T-C-G-C-A-G-G-C, and OR = 2.512), and five (A-C-T-C-C-C-G, OR = 0.634; G-A-G-C-C-C-G, OR = 4.047; G-A-T-T-G-C-G, OR = 0.499; G-C-G-T-C-A-G, and OR = 7.299; G-C-T-C-C-A-G, OR = 1.434) haplotypes were significantly associated with pregnancy with chronic hypertension, gestational hypertension, preeclampsia, or preeclampsia superimposed on chronic hypertension and HDP.

Conclusion: These variant MT alleles and their combination patterns may be used as genetic markers for predicting HDP susceptibility.