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BMI1 promotes spermatogonial stem cell maintenance by epigenetically repressing Wnt10b/β-catenin signaling.

ABSTRACT: The self-renewal of spermatogonial stem cells (SSCs) requires a special microenvironment and is strictly controlled. Previously, we identified BMI1 as a key regulator of spermatogenesis in a knock-out mouse model. However, the mechanisms by which BMI1 regulates SSC maintenance remain largely unknown. Herein, we show that BMI1 is essential for SSC maintenance. BMI1 directs the transcriptional repression of target genes by increasing H2AK119ub and reducing H3K4me3 in SSCs. Furthermore, BMI1 inhibition resulted in the transcriptional activation of Wnt10b and thereby promoted the nuclear translocation of β-catenin in SSCs. Importantly, the suppression of Wnt/β-catenin signaling restored both the cytoplasmic expression of β-catenin and SSC maintenance in BMI1-deficient SSCs. Finally, we demonstrated that Wnt/β-catenin signaling was also involved in BMI1-mediated SSC maintenance in vivo. Altogether, our study not only reveals a novel mechanism for BMI1 in the process of SSC maintenance, but also provides a potential new strategy for treating male infertility.

SUBMITTER: Yu J

PROVIDER: S-EPMC9066105 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature

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BMI1 promotes spermatogonial stem cell maintenance by epigenetically repressing Wnt10b/β-catenin signaling.

Yu Jun J Shen Cong C Lin Meng M Chen Xia X Dai Xiuliang X Li Zhiran Z Wu Yunhao Y Fu Yangbo Y Lv Jinxing J Huang Xiaoyan X Zheng Bo B Sun Fei F

International journal of biological sciences 20220404 7

The self-renewal of spermatogonial stem cells (SSCs) requires a special microenvironment and is strictly controlled. Previously, we identified BMI1 as a key regulator of spermatogenesis in a knock-out mouse model. However, the mechanisms by which BMI1 regulates SSC maintenance remain largely unknown. Herein, we show that BMI1 is essential for SSC maintenance. BMI1 directs the transcriptional repression of target genes by increasing H2AK119ub and reducing H3K4me3 in SSCs. Furthermore, BMI1 inhibi ...[more]

PMID: 35541907

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Project description:BackgroundHepatocellular carcinoma (HCC) is the second lethal malignancy among all cancers. Many molecular alterations have been found in HCC. However, the interactions and modulatory mechanisms among these molecules in HCC are still unclear.MethodsCTB-193M12.5 expression in tissues and cells were detected by quantitative polymerase chain reaction (qPCR). In vitro experiments were conducted to evaluate the function of CTB-193M12.5 in cell proliferation, apoptosis, migration and invasion. The interaction between CTB-193M12.5 and nuclear receptor binding SET domain-containing protein 1 (NSD1) was assessed by RNA-protein pull-down and RNA immunoprecipitation assays. The roles of CTB-193M12.5 on WNT10B and Wnt/β-catenin signaling was detected by chromatin immunoprecipitation assay, qPCR, Western blot, and dual luciferase reporter assay.ResultsWe identified a novel prognosis-related long noncoding RNA (lncRNA) CTB-193M12.5 in HCC. CTB-193M12.5 was upregulated in HCC and its high expression was correlated with alpha fetoprotein, large tumor size, aggressive clinical characteristics, and poor survival. Functional experiments showed that CTB-193M12.5 enhanced HCC cellular proliferation, suppressed HCC cellular apoptosis, and promoted HCC cellular migration and invasion. CTB-193M12.5 knockdown exerted opposite effects in HCC. Mechanistic investigation demonstrated that CTB-193M12.5 was mainly distributed in nucleus. Histone methyltransferase NSD1 was identified as a CTB-193M12.5 interactor. CTB-193M12.5 bound and recruited NSD1 to the promoter of WNT10B, leading to an increase in di-methylation of histone H3 at lysine 36 (H3K36me2) and the reduction of tri-methylation of histone H3 at lysine 27 (H3K27me3) at WNT10B promoter. Therefore, CTB-193M12.5 epigenetically activated WNT10B transcription. Through upregulating WNT10B, CTB-193M12.5 further activated Wnt/β-catenin signaling. Functional rescue experiments demonstrated that overexpression of WNT10B reversed the tumor suppressive roles of CTB-193M12.5 knockdown, while Wnt/β-catenin signaling inhibitor ICG-001 abolished the oncogenic roles of CTB-193M12.5 overexpression.ConclusionCTB-193M12.5 was a highly expressed and poor prognosis-related lncRNA in HCC. CTB-193M12.5 functioned as an oncogenic lncRNA through promoting NSD1-mediated WNT10B/Wnt/β-catenin signaling activation.

Project description:BackgroundOsteosarcoma (OS) is the most common malignant tumor of bone, and the clinical efficacy of current treatments and associated survival rates need to be further improved by employing novel therapeutic strategies. Although various studies have shown that BMI1 protein is universally upregulated in OS cells and tissues, its specific role and underlying mechanism have not yet been fully explored.MethodsExpression of BMI1 protein in OS cells was detected by western blot. The effect of BMI1 on proliferation and migration of OS cells (143B and U-2OS cell lines) was investigated in vitro using CCK-8, colony formation and transwell assays, and in vivo using subcutaneous tumorigenesis and lung metastasis assays in xenograft nude mice. Expression of epithelial-mesenchymal transition (EMT)-associated proteins was detected by immunofluorescence imaging. Bioinformatic analysis was performed using ENCODE databases to predict downstream targets of BMI1. SIK1 mRNA expression in osteosarcoma cells was detected by quantitative real-time reverse transcription PCR (qPCR). Chromatin immunoprecipitation-qPCR (ChIP-qPCR) was used to investigate expression of BMI1-associated, RING1B-associated, H2AK119ub-associated and H3K4me3-associated DNA at the putative binding region of BMI1 on the SIK1 promoter in OS cells.ResultsUsing both in vitro and in vivo experimental approaches, we found that BMI1 promotes OS cell proliferation and metastasis. The tumor suppressor SIK1 was identified as the direct target gene of BMI1 in OS cells. In vitro experiments demonstrated that SIK1 could inhibit proliferation and migration of OS cells. Inhibition of SIK1 largely rescued the altered phenotypes of BMI1-deficient OS cells. Mechanistically, we demonstrated that BMI1 directly binds to the promoter region of SIK1 in a complex with RING1B to promote monoubiquitination of histone H2A at lysine 119 (H2AK119ub) and inhibit H3K4 trimethylation (H3K4me3), resulting in inhibition of SIK1 transcription. We therefore suggest that BMI1 promotes OS cell proliferation and metastasis by inhibiting SIK1.ConclusionsOur results reveal a novel molecular mechanism of OS development promoted by BMI1 and provides a new potential target for OS treatment.

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Project description:PurposeSpermatogonial stem cells (SSCs) are essential for maintaining reproductive function in males. B-lymphoma Mo-MLV insertion region 1 (BMI1) is a vital transcription repressor that regulates cell proliferation and differentiation. However, little is known about the role of BMI1 in mediating the fate of mammalian SSCs and in male reproduction. This study investigated whether BMI1 is essential for male reproduction and the role of alpha-tocopherol (α-tocopherol), a protective agent for male fertility, as a modulator of BMI1 both in vitro and in vivo.MethodsMethyl thiazolyl tetrazolium (MTT) and 5-ethynyl-2'-deoxyuridine (EDU) assays were used to assess the effect of BMI1 on the proliferative ability of the mouse SSC line C18-4. Real-time polymerase chain reaction (PCR), western blotting, and immunofluorescence were applied to investigate changes in the mRNA and protein expression levels of BMI1. Male mice were used to investigate the effect of α-tocopherol and a BMI1 inhibitor on reproduction-associated functionality in vivo.ResultsAnalysis revealed that BMI1 was expressed at high levels in testicular tissues and spermatogonia in mice. The silencing of BMI1 inhibited the proliferation of SSCs and DNA synthesis and enhanced the levels of γ-H2AX. α-tocopherol enhanced the proliferation and DNA synthesis of C18-4 cells, and increased the levels of BMI1. Notably, α-tocopherol rescued the inhibition of cell proliferation and DNA damage in C18-4 cells caused by the silencing of BMI1. Furthermore, α-tocopherol restored sperm count (Ctrl vs. PTC-209, p = 0.0034; Ctrl vs. PTC-209 + α-tocopherol, p = 0.7293) and normalized sperm malformation such as broken heads, irregular heads, lost and curled tails in vivo, as demonstrated by its antagonism with the BMI1 inhibitor PTC-209.ConclusionAnalysis demonstrated that α-tocopherol is a potent in vitro and in vivo modulator of BMI1, a transcription factor that plays an important role in in SSC proliferation and spermatogenesis. Our findings identify a new target and strategy for treating male infertility that deserves further pre-clinical investigation.

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BMI1 promotes spermatogonial stem cell maintenance by epigenetically repressing Wnt10b/β-catenin signaling.

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BMI1 promotes spermatogonial stem cell maintenance by epigenetically repressing Wnt10b/β-catenin signaling.

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