UHRF1 establishes crosstalk between somatic and germ cells in male reproduction

Betaine alleviates spermatogenic cells apoptosis of oligoasthenozoospermia rat model by up-regulating methyltransferases and affecting DNA methylation

BACKGROUND

Oligoasthenozoospermia is the most common type of semen abnormality in male infertile patients. Betaine (BET) has been proved to have pharmacological effects on improving semen quality. BET also belongs to endogenous physiological active substances in the testis. However, the physiological function of BET in rat testis and its pharmacological mechanism against oligoasthenozoospermia remain unclear.

PURPOSE

This research aims to prove the therapeutic effect and potential mechanism of BET on oligoasthenozoospermia rat model induced by Tripterygium wilfordii glycosides (TWGs).

METHODS

The oligoasthenozoospermia rat model was established by a continuous gavage of TWGs (60 mg/kg) for 28 days. Negative control group, oligoasthenozoospermia group, positive drug group (levocarnitine, 300 mg/kg), and 200 mg/kg, 400 mg/kg, and 800 mg/kg BET groups were created for exploring the therapeutic effect of BET on the oligoasthenozoospermia rat model. The therapeutic effect was evaluated by HE and TUNEL staining. Immunofluorescence assay of DNMT3A, PIWIL1, PRMT5, SETDB1, BHMT2, and METTL3, methylation capture sequencing, Pi-RNA sequencing, and molecular docking were used to elucidate potential pharmacological mechanisms.

RESULTS

It is proved that BET can significantly restore testicular pathological damage induced by TWGs, which also can significantly reverse the apoptosis of spermatogenic cells. The spermatogenic cell protein expression levels of DNMT3A, PIWIL1, PRMT5, SETDB1, BHMT2, and METTL3 significantly decreased in oligoasthenozoospermia group. 400 mg/kg and 800 mg/kg BET groups can significantly increase expression level of the above-mentioned proteins. Methylation capture sequencing showed that BET can significantly increase the 5mC methylation level of Spata, Spag, and Specc spermatogenesis-related genes. Pi-RNA sequencing proved that the above-mentioned genes produce a large number of Pi-RNA under BET intervention. Pi-RNA can form complexes with PIWI proteins to participate in DNA methylation of target genes. Molecular docking indicated that BET may not directly act as substrate for methyltransferase and instead participates in DNA methylation by promoting the methionine cycle and increasing S-adenosylmethionine synthesis.

CONCLUSION

BET has a significant therapeutic effect on oligoasthenozoospermia rat model induced by TWPs. The mechanism mainly involves that BET can increase the methylation level of Spata, Specc, and Spag target genes through the PIWI/Pi-RNA pathway and up-regulation of methyltransferases (including DNA methyltransferases and histone methyltransferases).

The E3 ubiquitin-protein ligase UHRF1 promotes adipogenesis and limits fibrosis by suppressing GPNMB-mediated TGF-β signaling

The E3 ubiquitin-ligase UHRF1 is an epigenetic regulator coordinating DNA methylation and histone modifications. However, little is known about how it regulates adipogenesis or metabolism. In this study, we discovered that UHRF1 is a key regulatory factor for adipogenesis, and we identified the altered molecular pathways that UHRF1 targets. Using CRISPR/Cas9-based knockout strategies, we discovered the whole transcriptomic changes upon UHRF1 deletion. Bioinformatics analyses revealed that key adipogenesis regulators such PPAR-γ and C/EBP-α were suppressed, whereas TGF-β signaling and fibrosis markers were upregulated in UHRF1-depleted differentiating adipocytes. Furthermore, UHRF1-depleted cells showed upregulated expression and secretion of TGF-β1, as well as the glycoprotein GPNMB. Treating differentiating preadipocytes with recombinant GPNMB led to an increase in TGF-β protein and secretion levels, which was accompanied by an increase in secretion of fibrosis markers such as MMP13 and a reduction in adipogenic conversion potential. Conversely, UHRF1 overexpression studies in human cells demonstrated downregulated levels of GPNMB and TGF-β, and enhanced adipogenic potential. In conclusion, our data show that UHRF1 positively regulates 3T3-L1 adipogenesis and limits fibrosis by suppressing GPNMB and TGF-β signaling cascade, highlighting the potential relevance of UHRF1 and its targets to the clinical management of obesity and linked metabolic disorders.

hnRNPA2B1 represses the disassembly of arsenite-induced stress granules and is essential for male fertility

Although the composition and assembly of stress granules (SGs) are well understood, the molecular mechanisms underlying SG disassembly remain unclear. Here, we identify that heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNPA2B1) is associated with SGs and that its absence specifically enhances the disassembly of arsenite-induced SGs depending on the ubiquitination-proteasome system but not the autophagy pathway. hnRNPA2B1 interacts with many core SG proteins, including G3BP1, G3BP2, USP10, and Caprin-1; USP10 can deubiquitinate G3BP1; and hnRNPA2B1 depletion attenuates the G3BP1-USP10/Caprin-1 interaction but elevates the G3BP1 ubiquitination level under arsenite treatment. Moreover, the disease-causing mutation FUSR521C also disassembles faster from SGs in HNRNPA2B1 mutant cells. Furthermore, knockout of hnRNPA2B1 in mice leads to Sertoli cell-only syndrome (SCOS), causing complete male infertility. Consistent with this, arsenite-induced SGs disassemble faster in Hnrnpa2b1 knockout (KO) mouse Sertoli cells as well. These findings reveal the essential roles of hnRNPA2B1 in regulating SG disassembly and male mouse fertility.

Effect of tumor exosome-derived Lnc RNA HOTAIR on the growth and metastasis of gastric cancer

PURPOSE

HOX transcribed antisense RNA (HOTAIR) is a long noncoding RNA (LncRNA) that promotes tumor progression. Exosomes are critically involved in cancer progression. The presence of HOTAIR in the circulating exosomes and the roles of exosomal HOTAIR in gastric cancer (GC) remains unknown. This study aimed to investigate the role of HOTAIR in exosomes in promoting the growth and metastasis of GC.

METHODS

Serum exosomes from GC patients were captured by CD63 immunoliposome magnetic spheres (CD63-IMS), and the biological characteristics of the exosomes were identified. The expression levels of HOTAIR in GC cells, tissues, serum and serum exosomes were detected by fluorescence quantitative PCR (qRT-PCR), and the clinicopathological correlation was statistically analyzed. The growth and metastasis abilities of GC cells with HOTAIR knockdown in vitro were evaluated by cell experiment. The effects of HOTAIR highly-expressed NCI-N87 cell-derived exosomes were used to treat HOTAIR lowly-expressed MKN45 cells on GC growth and metastasis were also evaluated.

RESULTS

The exosomes isolated by CD63-IMS had a particle size of 89.78 ± 4.8 nm and were oval membranous particles. The expression of HOTAIR in tumor tissues and serum of GC patients was increased (P < 0.05), and the expression of HOTAIR in serum exosomes was significantly increased (P < 0.01). The in NCI-N87 and MKN45 cell experiment demonstrated that HOTAIR knockdown by RNA interference suppressed cell growth and metastasis in NCI-N87 cells. Coculture of exosomes secreted by NCI-N87 cells with MKN45 cells significantly increased the expression of HOTAIR, and enhanced cell growth and metastasis.

CONCLUSION

LncRNA HOTAIR can be used as a potential biomarker which provides a new way for the diagnosis and treatment of GC.

UHRF1 inhibition epigenetically reprograms cancer stem cells to suppress the tumorigenic phenotype of hepatocellular carcinoma

Cancer stem cells (CSCs) contribute to tumor initiation, progression, and recurrence in many types of cancer, including hepatocellular carcinoma (HCC). Epigenetic reprogramming of CSCs has emerged as a promising strategy for inducing the transition from malignancy to benignity. Ubiquitin-like with PHD and ring finger domains 1 (UHRF1) is required for DNA methylation inheritance. Here, we investigated the role and mechanism of UHRF1 in regulating CSC properties and evaluated the impact of UHRF1 targeting on HCC. Hepatocyte-specific Uhrf1 knockout (Uhrf1^HKO) strongly suppressed tumor initiation and CSC self-renewal in both diethylnitrosamine (DEN)/CCl₄-induced and Myc-transgenic HCC mouse models. Ablation of UHRF1 in human HCC cell lines yielded consistent phenotypes. Integrated RNA-seq and whole genome bisulfite sequencing revealed widespread hypomethylation induced by UHRF1 silencing epigenetically reprogrammed cancer cells toward differentiation and tumor suppression. Mechanistically, UHRF1 deficiency upregulated CEBPA and subsequently inhibited GLI1 and Hedgehog signaling. Administration of hinokitiol, a potential UHRF1 inhibitor, significantly reduced tumor growth and CSC phenotypes in mice with Myc-driven HCC. Of pathophysiological significance, the expression levels of UHRF1, GLI1, and key axis proteins consistently increased in the livers of mice and patients with HCC. These findings highlight the regulatory mechanism of UHRF1 in liver CSCs and have important implications for the development of therapeutic strategies for HCC.

FZD7, Regulated by Non-CpG Methylation, Plays an Important Role in Immature Porcine Sertoli Cell Proliferation

The regulatory role of non-CpG methylation in mammals has been important in whole-genome bisulfite sequencing. It has also been suggested that non-CpG methylation regulates gene expression to affect the development and health of mammals. However, the dynamic regulatory mechanisms of genome-wide, non-CpG methylation during testicular development still require intensive study. In this study, we analyzed the dataset from the whole-genome bisulfite sequencing (WGBS) and the RNA-seq of precocious porcine testicular tissues across two developmental stages (1 and 75 days old) in order to explore the regulatory roles of non-CpG methylation. Our results showed that genes regulated by non-CpG methylation affect the development of testes in multiple pathways. Furthermore, several hub genes that are regulated by non-CpG methylation during testicular development-such as VEGFA, PECAM1, and FZD7-were also identified. We also found that the relative expression of FZD7 was downregulated by the zebularine-induced demethylation of the first exon of FZD7. This regulatory relationship was consistent with the results of the WGBS and RNA-seq analysis. The immature porcine Sertoli cells were transfected with RNAi to mimic the expression patterns of FZD7 during testicular development. The results of the simulation test showed that cell proliferation was significantly impeded and that cell cycle arrest at the G2 phase was caused by the siRNA-induced FZD7 inhibition. We also found that the percentage of early apoptotic Sertoli cells was decreased by transfecting them with the RNAi for FZD7. This indicates that FZD7 is an important factor in linking the proliferation and apoptosis of Sertoli cells. We further demonstrated that Sertoli cells that were treated with the medium collected from apoptotic cells could stimulate proliferation. These findings will contribute to the exploration of the regulatory mechanisms of non-CpG methylation in testicular development and of the relationship between the proliferation and apoptosis of normal somatic cells.

hnRNPH1 establishes Sertoli-germ cell crosstalk through cooperation with PTBP1 and AR, and is essential for male fertility in mice

Spermatogenesis depends on the crosstalk of Sertoli cells (SCs) and germ cells. However, the gene regulatory network establishing the communications between SCs and germ cells remains unclear. Here, we report that heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) in SCs is essential for the establishment of crosstalk between SCs and germ cells. Conditional knockout of hnRNPH1 in mouse SCs leads to compromised blood-testis barrier function, delayed meiotic progression, increased germ cell apoptosis, sloughing of germ cells and, eventually, infertility of mice. Mechanistically, we discovered that hnRNPH1 could interact with the splicing regulator PTBP1 in SCs to regulate the pre-mRNA alternative splicing of the target genes functionally related to cell adhesion. Interestingly, we also found hnRNPH1 could cooperate with the androgen receptor, one of the SC-specific transcription factors, to modulate the transcription level of a group of genes associated with the cell-cell junction and EGFR pathway by directly binding to the gene promoters. Collectively, our findings reveal a crucial role for hnRNPH1 in SCs during spermatogenesis and uncover a potential molecular regulatory network involving hnRNPH1 in establishing Sertoli-germ cell crosstalk.

hnRNPH1 recruits PTBP2 and SRSF3 to modulate alternative splicing in germ cells

Coordinated regulation of alternative pre-mRNA splicing is essential for germ cell development. However, the underlying molecular mechanism that controls alternative mRNA expression during germ cell development remains elusive. Herein, we show that hnRNPH1 is highly expressed in the reproductive system and recruits the PTBP2 and SRSF3 to modulate the alternative splicing in germ cells. Conditional knockout Hnrnph1 in spermatogenic cells causes many abnormal splicing events, thus affecting the genes related to meiosis and communication between germ cells and Sertoli cells. This is characterized by asynapsis of chromosomes and impairment of germ-Sertoli communications, which ultimately leads to male sterility. Markedly, Hnrnph1 germline-specific mutant female mice are also infertile, and Hnrnph1-deficient oocytes exhibit a similar defective synapsis and cell-cell junction as seen in Hnrnph1-deficient male germ cells. Collectively, our data support a molecular model wherein hnRNPH1 governs a network of alternative splicing events in germ cells via recruitment of PTBP2 and SRSF3.

Coordinated regulation of alternative splicing is essential for germ cell development. Here, the authors report that hnRNPH1 interacts with alternative splicing factors PTBP2 and SRSF3 in the germline to regulate pre-mRNA alternative splicing.