GGNBP2 acts as a tumor suppressor by inhibiting estrogen receptor α activity in breast cancer cells

GGNBP2 regulates histone ubiquitination and methylation in spermatogenesis

Gametogenetin binding protein 2 (GGNBP2) was indispensable in normal spermatids for transformation into mature spermatozoa in mice, and when Gametogenetin binding protein 2 is bound to BRCC36 and RAD51, the complex participates in repairing DNA double-strand breaks (DSB) during the meiotic progression of spermatocytes. Ggnbp2 knockout resulted in the up-regulation of H2AK119ubi and down-regulation of H2BK120ubi in GC-2 cells (mouse spermatogonia-derived cell line) and postnatal day 18 testis lysate. Our results also demonstrated that Gametogenetin binding protein 2 inducedASXL1 to activate the deubiquitinating enzyme BAP1 in deubiquitinating H2A, while Gametogenetin binding protein 2 knockout disrupted the interaction between ASXL1 and BAP1, resulting in BAP1 localization change. Furthermore, the Gametogenetin binding protein 2 deletion reduced H2B ubiquitination by affecting E2 enzymes and E3 ligase binding. Gametogenetin binding protein 2 regulated H2A and H2B ubiquitination levels and controlled H3K27 and H3K79 methylation by PRC2 subunits and histone H3K79 methyltransferase. Altogether, our results suggest that Ggnbp2 knockout increased DNA damage response by promoting H2A ubiquitination and H3K27trimethylation (H3K27me3) and reduced nucleosome stability by decreasing H2B ubiquitination and H3K79 dimethylation (H3K79me2), revealing new mechanisms of epigenetic phenomenon during spermatogenesis. Gametogenetin binding protein 2 seems critical in regulating histone modification and chromatin structure in spermatogenesis.

Dissecting shared genetic architecture between obesity and multiple sclerosis

BACKGROUND

Observational studies have associated obesity with an increased risk of multiple sclerosis (MS). However, the role of genetic factors in their comorbidity remains largely unknown. Our study aimed to investigate the shared genetic architecture underlying obesity and MS.

METHODS

By leveraging data from genome-wide association studies, we investigated the genetic correlation of body mass index (BMI) and MS by linkage disequilibrium score regression and genetic covariance analyser. The casualty was identified by bidirectional Mendelian randomisation. Linkage disequilibrium score regression in specifically expressed genes and multimarker analysis of GenoMic annotation was utilised to explore single-nucleotide polymorphism (SNP) enrichment at the tissue and cell-type levels. Shared risk SNPs were derived using cross-trait meta-analyses and Heritability Estimation from Summary Statistics. We explored the potential functional genes using summary-data-based Mendelian randomization (SMR). The expression profiles of the risk gene in tissues were further examined.

FINDINGS

We found a significantly positive genetic correlation between BMI and MS, and the causal association of BMI with MS was supported (β = 0.22, P = 8.03E-05). Cross-trait analysis yielded 39 shared risk SNPs, and the risk gene GGNBP2 was consistently identified in SMR. We observed tissue-specific level SNP heritability enrichment for BMI mainly in brain tissues for MS in immune-related tissues, and cell-type-specific level SNP heritability enrichment in 12 different immune cell types in brain, spleen, lung, and whole blood. The expressions of GGNBP2 were significantly altered in the tissues of patients with obesity or MS compared to those of control subjects.

INTERPRETATION

Our study indicates the genetic correlation and shared risk genes between obesity and MS. These findings provide insights into the potential mechanisms behind their comorbidity and the future development of therapeutics.

FUNDING

This work was funded by the National Natural Science Foundation of China (82171698, 82170561, 81300279, and 81741067), the Program for High-level Foreign Expert Introduction of China (G2022030047L), the Natural Science Foundation for Distinguished Young Scholars of Guangdong Province (2021B1515020003), Natural Science Foundation of Guangdong Province (2022A1515012081), the Foreign Distinguished Teacher Program of Guangdong Science and Technology Department (KD0120220129), the Climbing Programme of Introduced Talents and High-level Hospital Construction Project of Guangdong Provincial People's Hospital (DFJH201803, KJ012019099, KJ012021143, and KY012021183), and in part by VA Clinical Merit and ASGE clinical research funds (FWL).

Identification of TSGA10 and GGNBP2 splicing variants in 5' untranslated region with distinct expression profiles in brain tumor samples

Introduction

Brain tumors (BTs) are perceived as one of the most common malignancies among children. The specific regulation of each gene can play a critical role in cancer progression. The present study aimed to determine the transcripts of the TSGA10 and GGNBP2 genes, considering the alternative 5'UTR region, and investigating the expression of these different transcripts in BTs.

Material and methods

Public data on brain tumor microarray datasets in GEO were analyzed with R software to evaluate the expression levels of TSGA10 and GGNBP2 genes (the Pheatmap package in R was also used to plot DEGs in a heat map). In addition, to validate our in-silico data analysis, RT-PCR was performed to determine the splicing variants of TSGA10 and GGNBP2 genes in testis and brain tumor samples. The expression levels of splice variants of these genes were analyzed in 30 brain tumor samples and two testicular tissue samples as a positive control.

Results

In silico results show that the differential expression levels of TSGA10 and GGNBP2 were significant in the GEO datasets of BTs compared to normal samples (with adjusted p-value<0.05 and log fold change > 1). This study's experimental results showed that the TSGA10 gene produces four different transcripts with two distinct promoter regions and splicing exon 4. The relative mRNA expression of transcripts without exon 4 was higher than transcripts with exon 4 in BT samples (p-value<001). In GGNBP2, exon 2 in the 5'UTR region and exon 6 in the coding sequence were spliced. The expression analysis results showed that the relative mRNA expression of transcript variants without exon 2 was higher than other transcript variants with exon 2 in BT samples (p-value<001).

Conclusion

The decreased expression levels of transcripts with longer 5'UTR in BT samples than in testicular or low-grade brain tumor samples may decrease their translation efficiency. Therefore, decreased amounts of TSGA10 and GGNBP2 as potential tumor suppressor proteins, especially in high-grade brain tumors, may cause cancer development by angiogenesis and metastasis.

Fbxo45 promotes the malignant development of esophageal squamous cell carcinoma by targeting GGNBP2 for ubiquitination and degradation

Esophageal squamous cell carcinoma (ESCC) is one of the most common and deadly cancers. Fbxo45, a substrate recognition subunit of E3 ligase, is critically involved in tumorigenesis and tumor progression. However, the function of Fbxo45 and the underlying mechanisms have not been elucidated in ESCC. We used cellular and molecular methods to explore the molecular basis of Fbxo45-mediated ESCC development. We found that ectopic overexpression of Fbxo45 promoted the growth of Kyse-150, Kyse30 and ECA-109 cells and inhibited the apoptosis. Moreover, overexpression of Fbxo45 promoted the migration and invasion of ESCC cells. Consistently, knockdown of Fbxo45 exhibited the opposite effects on ESCC cells. Mechanistically, we observed that Fbxo45 binds to GGNBP2 via its SPRY domain and targets GGNBP2 for ubiquitination and degradation. GGNBP2 overexpression exhibited anticancer activity in ESCC cells. Furthermore, Fbxo45 exerted its functions by regulating GGNBP2 stability in ESCC cells. Notably, overexpression of Fbxo45 facilitated tumor growth in mice. Strikingly, Fbxo45 was highly expressed in ESCC tissues, and GGNBP2 had a lower expression in ESCC specimens. High expression of Fbxo45 and low expression of GGNBP2 were associated with poor prognosis in ESCC patients. Fbxo45 was negatively correlated with GGNBP2 expression in ESCC tissues. Therefore, Fbxo45 serves as an oncoprotein to promote ESCC tumorigenesis by targeting the stability of the tumor suppressor GGNBP2 in ESCC.

Amyotrophic Lateral Sclerosis: A Diet Review

Amyotrophic lateral sclerosis (ALS) is a fatal disease related to upper and lower motor neurons degeneration. Although the environmental and genetic causes of this disease are still unclear, some factors involved in ALS onset such as oxidative stress may be influenced by diet. A higher risk of ALS has been correlated with a high fat and glutamate intake and β-methylamino-L-alanine. On the contrary, a diet based on antioxidant and anti-inflammatory compounds, such as curcumin, creatine, coenzyme Q10, vitamin E, vitamin A, vitamin C, and phytochemicals could reduce the risk of ALS. However, data are controversial as there is a discrepancy among different studies due to a limited number of samples and the many variables that are involved. In addition, an improper diet could lead to an altered microbiota and consequently to an altered metabolism that could predispose to the ALS onset. In this review we summarized some research that involve aspects related to ALS such as the epidemiology, the diet, the eating behaviour, the microbiota, and the metabolic diseases. Further research is needed to better comprehend the role of diet and the metabolic diseases in the mechanisms leading to ALS onset and progression.

Genome-wide genetic links between amyotrophic lateral sclerosis and autoimmune diseases

BACKGROUND

Epidemiological and clinical studies have suggested comorbidity between amyotrophic lateral sclerosis (ALS) and autoimmune disorders. However, little is known about their shared genetic architecture.

METHODS

To examine the relation between ALS and 10 autoimmune diseases, including asthma, celiac disease (CeD), Crohn's disease (CD), inflammatory bowel disease (IBD), multiple sclerosis (MS), psoriasis, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), and ulcerative colitis (UC), and identify shared risk loci, we first estimated the genetic correlation using summary statistics from genome-wide association studies, and then analyzed the genetic enrichment leveraging the conditional false discovery rate statistical method.

RESULTS

We identified a significant positive genetic correlation between ALS and CeD, MS, RA, and SLE, as well as a significant negative genetic correlation between ALS and IBD, UC, and CD. Robust genetic enrichment was observed between ALS and CeD and MS, and moderate enrichment was found between ALS and UC and T1D. Thirteen shared genetic loci were identified, among which five were suggestively significant in another ALS GWAS, namely rs3828599 (GPX3), rs3849943 (C9orf72), rs7154847 (G2E3), rs6571361 (SCFD1), and rs9903355 (GGNBP2). By integrating cis-expression quantitative trait loci analyses in Braineac and GTEx, we further identified GGNBP2, ATXN3, and SLC9A8 as novel ALS risk genes. Functional enrichment analysis indicated that the shared risk genes were involved in four pathways including membrane trafficking, vesicle-mediated transport, ER to Golgi anterograde transport, and transport to the Golgi and subsequent modification.

CONCLUSIONS

Our findings demonstrate a specific genetic correlation between ALS and autoimmune diseases and identify shared risk loci, including three novel ALS risk genes. These results provide a better understanding for the pleiotropy of ALS and have implications for future therapeutic trials.

Shared genetic links between amyotrophic lateral sclerosis and obesity-related traits: a genome-wide association study

Epidemiological and clinical studies have suggested comorbidities between amyotrophic lateral sclerosis (ALS) and obesity-related traits. However, little is known about their shared genetic architecture. To examine whether genetic enrichment exists between ALS and obesity-related traits and to identify shared risk loci, we analyzed summary statistics from genome-wide association studies using the conditional false discovery rate statistical framework, and further conducted functional enrichment analysis. Robust genetic enrichment was observed for ALS conditional on body mass index, body fat percentage, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and type 2 diabetes. Nine shared genetic loci were identified, among which 6 were replicated in a second ALS cohort, including C9orf72, G2E3, SCFD1, ATXN3, CLCN3 and GGNBP2. We further identified GGNBP2 as a novel ALS risk gene, by integrating summary data-based Mendelian randomization analysis. Functional enrichment analysis indicated that the shared risk genes were involved in 2 pathways, namely membrane trafficking and vesicle-mediated transport. These results provide a better understanding for the pleiotropy of ALS and have implications for future therapeutic trials.

Effects of zinc finger protein 403 on the proliferation, migration and invasion abilities of prostate cancer cells

Zinc finger protein 403 (ZFP403), located on human chromosome 17q12-21, is closely associated with the development of cancer. However, to date, there are a limited number of studies on the biological functions of this gene, particularly in prostate cancer (PCa). The results of the present study demonstrated that compared with normal tissues, the expression of ZFP403 was markedly lower in PCa tissues, as shown by the evaluation of the Gene Expression Profiling Interactive Analysis 2 database. The decreased expression of ZFP403 in PCa clinical tissues and cell lines was confirmed by immunohistochemistry, reverse transcription-quantitative PCR and western blot analysis. Using short harpin (sh)RNA inhibition, stably-silenced ZFP403 cell lines were then constructed by lentiviral transfection (LV-PC3-shRNA-1 and 2; LV-DU145-shRNA-1 and 2). The results revealed that the knockdown of ZFP403 in PCa cells promoted cellular proliferation, colony formation, migration and invasiveness in vitro. Moreover, the levels of tumor growth- and motility-related proteins were significantly altered after ZFP403-knockdown. A xenograft tumor model using nude mice was established to elucidate the role of ZFP403 in tumorigenesis in vivo. Tumor growth was significantly increased in mice injected with ZFP403-knockdown cells compared with the control mice. Overall, the findings of the present study demonstrate that ZFP403 functions as a tumor suppressor gene in PCa by affecting the proliferation, migration and invasiveness of PCa cells, suggesting its potential use as a clinical diagnostic marker.

Effects of gametogenetin-binding protein 2 on proliferation, invasion and migration of prostate cancer PC-3 cells

We aimed to assess the effects of gametogenetin-binding protein 2 (GGNBP2) on the proliferation, invasion and migration of prostate cancer PC-3 cells. PcDNA3-HisC-GGNBP2 was transfected to overexpress GGNBP2. Proliferation was tested by MTT assay, and migration and invasion were detected by Transwell assay. Cell cycle was detected by flow cytometry. The protein expressions of COX-2, cyclin D1, PI3K, Akt and p-Akt were detected by Western blot. A subcutaneous xenograft model of prostate cancer was established. Mice were randomly divided into three groups (n = 9) and intratumorally injected with pcDNA3-HisC-GGNBP2, pcDNA3-HisC and normal saline respectively. The xenograft tumour volume was measured every 3 days, and weight was measured after 2 weeks. After GGNBP2 overexpression, the proliferation, migration and invasion capacities of PC-3 cells decreased, and cell cycle was arrested in the G1 phase. The protein expressions of COX-2, cyclin D1, PI3K, Akt and p-Akt all reduced. The tumour volume and weight of pcDNA3-HisC-GGNBP2 group were significantly lower than those of pcDNA3-HisC group (p < .05). The proliferation capacity of GGNBP2-overexpressing prostate cancer cells is significantly attenuated, tumour growth is significantly inhibited, and cell cycle is arrested in the G1 phase. GGNBP2 overexpression affects the growth of castration-resistant prostate cancer via the PI3K/Akt signalling pathway.

GGN Promotes Tumorigenesis by Regulating Proliferation and Apoptosis in Colorectal Cancer

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. GGN is a germ cell-specific gene, but its function in CRC has been rarely reported to date. The aim of this study was to investigate the potential role of GGN in CRC tumorigenesis. Therefore, in this study, we examined the expression of GGN in CRC cell lines and tissues and its effects on cellular proliferation and apoptosis. We then explored the underlying mechanism. Our results showed that GGN was significantly overexpressed in both CRC cell lines and tissues. Silencing GGN robustly inhibited proliferation of CRC cells, and it also promoted apoptosis of CRC cells. Moreover, knockdown of GGN inhibited the expression of p-Akt in CRC cells. Taken together, these results showed that knockdown of GGN inhibits proliferation and promotes apoptosis of CRC cells through the PI3K/Akt signaling pathway. Our findings revealed for the first time a potential oncogenic role for GGN in CRC progress. This finding may provide a unique perspective on how a germ cell-specific gene might serve as a biomarker, or even as a therapeutic target, for CRC.

GGNBP2 suppresses triple-negative breast cancer aggressiveness through inhibition of IL-6/STAT3 signaling activation

BACKGROUND

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, lacking effective targeted therapies, and whose underlying mechanisms are still unclear. The gene coding for Gametogenetin-binding protein (GGNBP2), also known as Zinc Finger Protein 403 (ZNF403), is located on chromosome 17q12-q23, a region known as a breast cancer susceptibility locus. We have previously reported that GGNBP2 functions as a tumor suppressor in estrogen receptor-positive breast cancer. The aim of this study was to evaluate the role and mechanisms of GGNBP2 in TNBC.

METHODS

The effect of GGNBP2 on TNBC aggressiveness was investigated both in vitro and in vivo. The protein and mRNA expression levels were analyzed by western blotting and reverse transcription quantitative polymerase chain reaction, respectively. Fluorescence-activated cell sorting analysis was used to evaluate the cell cycle distribution and cell apoptosis. Immunohistochemistry was used to determine the expression of GGNBP2 in breast cancer tissues.

RESULTS

We find that GGNBP2 expression decreases in TNBC tissues and is associated with the outcome of breast cancer patients. Furthermore, experimental overexpression of GGNBP2 in MDA-MB-231 and Cal51 cells suppresses cell proliferation, migration and invasion, reduces the cancer stem cell subpopulation, and promotes cell apoptosis in vitro as well as inhibits tumor growth in vivo. In these cell models, overexpression of GGNBP2 decreases the activation of IL-6/STAT3 signaling.

CONCLUSION

Our data demonstrate that GGNBP2 suppresses cancer aggressiveness by inhibition of IL-6/STAT3 activation in TNBC.

Ablation of Ggnbp2 impairs meiotic DNA double-strand break repair during spermatogenesis in mice

Gametogenetin (GGN) binding protein 2 (GGNBP2) is a zinc finger protein expressed abundantly in spermatocytes and spermatids. We previously discovered that Ggnbp2 resection caused metamorphotic defects during spermatid differentiation and resulted in an absence of mature spermatozoa in mice. However, whether GGNBP2 affects meiotic progression of spermatocytes remains to be established. In this study, flow cytometric analyses showed a decrease in haploid, while an increase in tetraploid spermatogenic cells in both 30‐ and 60‐day‐old Ggnbp2 knockout testes. In spread spermatocyte nuclei, Ggnbp2 loss increased DNA double‐strand breaks (DSB), compromised DSB repair and reduced crossovers. Further investigations demonstrated that GGNBP2 co‐immunoprecipitated with a testis‐enriched protein GGN1. Immunofluorescent staining revealed that both GGNBP2 and GGN1 had the same subcellular localizations in spermatocyte, spermatid and spermatozoa. Ggnbp2 loss suppressed Ggn expression and nuclear accumulation. Furthermore, deletion of either Ggnbp2 or Ggn in GC‐2spd cells inhibited their differentiation into haploid cells in vitro. Overexpression of Ggnbp2 in Ggnbp2 null but not in Ggn null GC‐2spd cells partially rescued the defect coinciding with a restoration of Ggn expression. Together, these data suggest that GGNBP2, likely mediated by its interaction with GGN1, plays a role in DSB repair during meiotic progression of spermatocytes.

Estrogen and progesterone promote breast cancer cell proliferation by inducing cyclin G1 expression

Breast cancer is the most common cause of cancer among women in most countries (WHO). Ovarian hormone disorder is thought to be associated with breast tumorigenesis. The present study investigated the effects of estrogen and progesterone administration on cell proliferation and underlying mechanisms in breast cancer MCF-7 cells. It was found that a single administration of estradiol (E2) or progesterone increased MCF-7 cell viability in a dose-dependent manner and promoted cell cycle progression by increasing the percentage of cells in the G2/M phase. A combination of E2 and progesterone led to a stronger effect than single treatment. Moreover, cyclin G1 was up-regulated by E2 and/or progesterone in MCF-7 cells. After knockdown of cyclin G1 in MCF-7 cells using a specific shRNA, estradiol- and progesterone-mediated cell viability and clonogenic ability were significantly limited. Additionally, estradiol- and progesterone-promoted cell accumulation in the G2/M phase was reversed after knockdown of cyclin G1. These data indicated that estrogen and progesterone promoted breast cancer cell proliferation by inducing the expression of cyclin G1. Our data indicated that novel therapeutics against cyclin G1 are promising for the treatment of estrogen- and progesterone-mediated breast cancer progression.

GGNBP2 is necessary for testis morphology and sperm development

Gametogenetin Binding Protein 2 (GGNBP2) was identified as a tumor suppressor and verified as such by several studies. GGNBP2 has also been reported to be essential for pregnancy maintenance via regulation of trophoblast stem cells. Gametogenetin (GGN) is a testicular germ cell-specific gene expressed in adult testes. As a potential GGN1-interacting protein, the role of GGNBP2 in spermatogenesis has not yet been clarified. We generated heterozygous GGNBP2 knockout mice and bred them by intercrossing. We found that among the offspring, homozygous GGNBP2 knockout (KO) mice were present in severely reduced numbers. The GGNBP2 KO pups developed normally, but the male siblings showed dramatically reduced fertility. In these male homozygous GGNBP2 KO mice, the only pathological finding was abnormal morphology of the testes and absence of spermatozoa. In addition, increased apoptosis was observed in the testes of GGNBP2 KO mice. SOX9 staining revealed that SOX9-positive Sertoli cells were absent in the seminiferous tubules. In homozygous mice, proliferating cell nuclear antigen (PCNA)-positive cells were localized in the lumen of the convoluted seminiferous tubules. These results suggest that GGNBP2 plays a key role in spermatogenesis by affecting the morphology and function of SOX9-positive Sertoli cells.

GGNBP2 Suppresses the Proliferation, Invasion, and Migration of Human Glioma Cells

Gliomas are the most common and aggressive type of primary adult brain tumors. Although GGNBP2 has previously been considered to be a tumor suppressor gene, little is known about the association between GGNBP2 and glioma. In this study, we clearly demonstrated that GGNBP2 was downexpressed in glioma tissues, and its downexpression is related to the pathological grade and overall survival of patients with gliomas. Overexpression of GGNBP2 suppressed the proliferation, migration, and invasion of glioma cells. Mechanistically, we demonstrated that the PI3K/Akt and Wnt/β-catenin signaling pathways were suppressed by GGNBP2 overexpression. In contrast, knockdown of GGNBP2 has precisely the opposite effect. Collectively, these data indicate that GGNBP2 shows tumor suppressive activity in human glioma cells and may stand out as a potential therapeutic target for glioma.