The testis-enriched histone demethylase, KDM4D, regulates methylation of histone H3 lysine 9 during spermatogenesis in the mouse but is dispensable for fertility

Structure-based mapping of the histone-binding pocket of KDM4D using functionalized tetrazole and pyridine core compounds

KDM4 histone demethylases became an exciting target for inhibitor development as the evidence linking them directly to tumorigenesis mounts. In this study, we set out to better understand the binding cavity using an X-ray crystallographic approach to provide a detailed landscape of possible interactions within the under-investigated region of KDM4. Our design strategy was based on utilizing known KDM binding motifs, such as nicotinic acid and tetrazolylhydrazides, as core motifs that we decided to enrich with flexible tails to map the distal histone binding site. The resulting X-ray structures of the novel compounds bound to KDM4D, a representative of the KDM4 family, revealed the interaction pattern with distal residues in the histone-binding site. The most prominent protein rearrangement detected upon ligand binding is the loop movement that blocks the accessibility to the histone binding site. Apart from providing new sites that potential inhibitors can target, the novel compounds may prove helpful in exploring the capacity of ligands to bind in sites distal to the cofactor-binding site of other KDMs or 2-oxoglutarate (2OG)-dependent oxygenases. The case study proves that combining a strong small binding motif with flexible tails to probe the binding pocket will facilitate lead discovery in classical drug-discovery campaigns, given the ease of accessing X-ray quality crystals.

Kdm4d mutant mice show impaired sperm motility and subfertility

Regulation of gene expression through histone modifications underlies cell homeostasis and differentiation. Kdm4d and Kdm4dl exhibit a high degree of similarity and demethylate H3K9me3. However, the physiological functions of these proteins remain unclear. In this study, we generated Kdm4dl mutant mice and found that Kdm4dl was dispensable for mouse development. However, through the generation of Kdm4d mutant mice, we unexpectedly found that Kdm4d mutant male mice were subfertile because of impaired sperm motility. The absence of Kdm4d was associated with an altered distribution of H3K9me3 in round spermatids, suggesting that the Kdm4d-mediated adjustment of H3K9me3 levels is required to generate motile sperm. Further analysis revealed that the absence of Kdm4d did not affect the functionality of sperm nuclei in generating offspring. As KDM4D is specifically expressed in the human testes, our results suggest that changes in KDM4D expression or its activity may be a risk factor for human infertility.

Unraveling the Impact of the PROCA1 Mutation in Male Infertility: Incorporating Whole Exome Sequencing in Teratozoospermia Patients and Analyzing Proca1 Knockout Mice

In the world, about 15% of couples are infertile, and nearly half of all infertility was caused by men. A large number of genetic mutations are thought to affect spermatogenesis by regulating acrosome formation. Here, we identified three patients harbouring the protein interacting with cyclin A1 (PROCA1) mutation by whole exome sequencing (WES) and Sanger sequencing among patients with predominantly acrosome-deficient teratozoospermia. However, the expression and roles of PROCA1 in infertile men remain unclear. We found that PROCA1 is predominantly expressed in the testis, where it is specifically localized to the acrosome of normal human sperm. Proca1 knockout (KO) mice were subsequently generated using CRISPR-Cas9 technology. However, Proca1 KO adult male mice were fertile, with testis-to-body weight ratios comparable to those of wild-type (WT) mice. Testicular tissue or sperm morphology were not significantly different in Proca1 KO mice compared to WT mice. Expression of the acrosome markers PNA and SP56 in the acrosome was comparable between Proca1 KO and WT mice. In summary, these findings suggested that the PROCA1 mutation identified in humans does not affect acrosome biogenesis in mice.

Oxygen-dependent histone lysine demethylase 4 restricts hepatitis B virus replication

Mammalian cells have evolved strategies to regulate gene expression when oxygen is limited. Hypoxia-inducible factors (HIF) are the major transcriptional regulators of host gene expression. We previously reported that HIFs bind and activate hepatitis B virus (HBV) DNA transcription under low oxygen conditions; however, the global cellular response to low oxygen is mediated by a family of oxygenases that work in concert with HIFs. Recent studies have identified a role for chromatin modifiers in sensing cellular oxygen and orchestrating transcriptional responses, but their role in the HBV life cycle is as yet undefined. We demonstrated that histone lysine demethylase 4 (KDM4) can restrict HBV, and pharmacological or oxygen-mediated inhibition of the demethylase increases viral RNAs derived from both episomal and integrated copies of the viral genome. Sequencing studies demonstrated that KDM4 is a major regulator of the hepatic transcriptome, which defines hepatocellular permissivity to HBV infection. We propose a model where HBV exploits cellular oxygen sensors to replicate and persist in the liver. Understanding oxygen-dependent pathways that regulate HBV infection will facilitate the development of physiologically relevant cell-based models that support efficient HBV replication.

Methylation of the epigenetic JMJD2D protein by SET7/9 promotes prostate tumorigenesis

How the function of the JMJD2D epigenetic regulator is regulated or whether it plays a role in prostate cancer has remained elusive. We found that JMJD2D was overexpressed in prostate tumors, stimulated prostate cancer cell growth and became methylated by SET7/9 on K427. Mutation of this lysine residue in JMJD2D reduced the ability of DU145 prostate cancer cells to grow, invade and form tumors and elicited extensive transcriptomic changes. This included downregulation of CBLC, a ubiquitin ligase gene with hitherto unknown functions in prostate cancer, and upregulation of PLAGL1, a transcription factor with reported tumor suppressive characteristics in the prostate. Bioinformatic analyses indicated that CBLC expression was elevated in prostate tumors. Further, downregulation of CBLC largely phenocopied the effects of the K427 mutation on DU145 cells. In sum, these data have unveiled a novel mode of regulation of JMJD2D through lysine methylation, illustrated how this can affect oncogenic properties by influencing expression of the CBLC gene, and established a pro-tumorigenic role for CBLC in the prostate. A corollary is that JMJD2D and CBLC inhibitors could have therapeutic benefits in the treatment of prostate and possibly other cancers.

Intracytoplasmic sperm injection induces transgenerational abnormalities in mice

In vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are 2 major assisted reproductive techniques (ARTs) used widely to treat infertility. Recently, spermatogonial transplantation emerged as a new ART to restore fertility to young patients with cancer after cancer therapy. To examine the influence of germ cell manipulation on behavior of offspring, we produced F1 offspring by a combination of two ARTs, spermatogonial transplantation and ICSI. When these animals were compared with F1 offspring produced by ICSI using fresh wild-type sperm, not only spermatogonial transplantation-ICSI mice but also ICSI-only control mice exhibited behavioral abnormalities, which persisted in the F2 generation. Furthermore, although these F1 offspring appeared normal, F2 offspring produced by IVF using F1 sperm and wild-type oocytes showed various types of congenital abnormalities, including anophthalmia, hydrocephalus, and missing limbs. Therefore, ARTs can induce morphological and functional defects in mice, some of which become evident only after germline transmission.

Vitamin C activates young LINE-1 elements in mouse embryonic stem cells via H3K9me3 demethylation

BACKGROUND

Vitamin C (vitC) enhances the activity of 2-oxoglutarate-dependent dioxygenases, including TET enzymes, which catalyse DNA demethylation, and Jumonji-domain histone demethylases. The epigenetic remodelling promoted by vitC improves the efficiency of induced pluripotent stem cell derivation, and is required to attain a ground-state of pluripotency in embryonic stem cells (ESCs) that closely mimics the inner cell mass of the early blastocyst. However, genome-wide DNA and histone demethylation can lead to upregulation of transposable elements (TEs), and it is not known how vitC addition in culture media affects TE expression in pluripotent stem cells.

RESULTS

Here we show that vitC increases the expression of several TE families, including evolutionarily young LINE-1 (L1) elements, in mouse ESCs. We find that TET activity is dispensable for L1 upregulation, and that instead it occurs largely as a result of H3K9me3 loss mediated by KDM4A/C histone demethylases. Despite increased L1 levels, we did not detect increased somatic insertion rates in vitC-treated cells. Notably, treatment of human ESCs with vitC also increases L1 protein levels, albeit through a distinct, post-transcriptional mechanism.

CONCLUSION

VitC directly modulates the expression of mouse L1s and other TEs through epigenetic mechanisms, with potential for downstream effects related to the multiple emerging roles of L1s in cellular function.

Testis-specific knockout of Kdm2a reveals nonessential roles in male fertility but partially compromises spermatogenesis

Lysine-specific histone demethylase 2 (Kdm2a) is a regulatory factor of histone modifications that participates in gametogenesis and embryonic development. The mis-regulation of Kdm2a can lead to aberrant gene expression, thereby contributing to abnormal cell proliferation, differentiation, apoptosis, and tumorigenesis. However, due to the potential confounding effects that are secondary to the loss of Kdm2a function from the soma in existing whole-animal mutants, the in vivo function of Kdm2a in spermatogenesis for male fertility remains unknown. Herein, we focus on exploring the spatiotemporal expression profile and biological functions of Kdm2a in the spermatogenesis and fertility of male mice. A testis-specific knockout Kdm2a model (Kdm2a cKO) was established by using the Stra8-Cre/loxP recombinase system to explore the roles of Kdm2a in male fertility. Our results showed that Kdm2a was ubiquitously expressed and dynamically distributed in multiple tissues and cell types in the testis of mice. Surprisingly, Kdm2a-deficient adult males were completely fertile and comparable with their control (Kdm2aflox/flox) counterparts. Despite the significantly reduced total number of sperm and density of seminiferous tubules in Kdm2a cKO testis accompanied by the degeneration of spermatogenesis, the fertilization ability and embryonic developmental competence of the Kdm2a cKO were comparable with those of their control littermates, suggesting that Kdm2a disruption did not markedly affect male fertility, at least during younger ages. Furthermore, Kdm2a homozygous mutants exhibited a lower total number and motility of sperm than the control group and showed notably affected serum 17β-estradiol concentration. Interestingly, the transcriptome sequencing revealed that the loss of Kdm2a remarkably upregulated the expression level of Kdm2b. This effect, in turn, may induce compensative effects in the case of Kdm2a deficiency to maintain normal male reproduction. Together, our results reveal that Kdm2a shows spatiotemporal expression during testicular development and that its loss is insufficient to compromise the production of spermatozoa completely. The homologous Kdm2b gene might compensate for the loss of Kdm2a. Our work provides a novel Kdm2a cKO mouse allowing for the efficient deletion of Kdm2a in a testis-specific manner, and further investigated the biological function of Kdm2a and the compensatory effects of Kdm2b. Our study will advance our understanding of underlying mechanisms in spermatogenesis and male fertility.

KDM4 Demethylases: Structure, Function, and Inhibitors

KDM4 histone demethylases mainly catalyze the removal of methyl marks from H3K9 and H3K36 to epigenetically regulate chromatin structure and gene expression. KDM4 expression is strictly regulated to ensure proper function in a myriad of biological processes, including transcription, cellular proliferation and differentiation, DNA damage repair, immune response, and stem cell self-renewal. Aberrant expression of KDM4 demethylase has been documented in many types of blood and solid tumors, and thus, KDM4s represent promising therapeutic targets. In this chapter, we summarize the current knowledge of the structures and regulatory mechanisms of KDM4 proteins and our understanding of their alterations in human pathological processes with a focus on development and cancer. We also review the reported KDM4 inhibitors and discuss their potential as therapeutic agents.

Recent Advances with KDM4 Inhibitors and Potential Applications

The histone lysine demethylase 4 (KDM4) family plays an important role in regulating gene transcription, DNA repair, and metabolism. The dysregulation of KDM4 functions is associated with many human disorders, including cancer, obesity, and cardiovascular diseases. Selective and potent KDM4 inhibitors may help not only to understand the role of KDM4 in these disorders but also to provide potential therapeutic opportunities. Here, we provide an overview of the field and discuss current status, challenges, and opportunities lying ahead in the development of KDM4-based anticancer therapeutics.

Histone Demethylase JMJD2D: A Novel Player in Colorectal and Hepatocellular Cancers

Simple Summary

Histone demethylase JMJD2D is a multifunctional epigenetic factor coordinating androgen receptor activation, DNA damage repair, DNA replication, cell cycle regulation, and inflammation modulation. JMJD2D is also a well-established epigenetic facilitator in the progression of multiple malignant tumors, especially in colorectal cancer (CRC) and hepatocellular cancer (HCC). This review aims to summarize the mechanisms of JMJD2D in promoting CRC and HCC progression, which provides novel ideas for targeting JMJD2D in oncotherapy. JMJD2D promotes gene transcription by reducing H3K9 methylation and serves as a coactivator to enhance the activities of multiple carcinogenic pathways, including Wnt/β-catenin, Hedgehog, HIF1, JAK-STAT3, and Notch signaling; or acts as an antagonist of the tumor suppressor p53.

Abstract

Posttranslational modifications (PTMs) of histones are well-established contributors in a variety of biological functions, especially tumorigenesis. Histone demethylase JMJD2D (also known as KDM4D), a member of the JMJD2 subfamily, promotes gene transcription by antagonizing H3K9 methylation. JMJD2D is an epigenetic factor coordinating androgen receptor activation, DNA damage repair, DNA replication, and cell cycle regulation. Recently, the oncogenic role of JMJD2D in colorectal cancer (CRC) and hepatocellular cancer (HCC) has been recognized. JMJD2D serves as a coactivator of β-catenin, Gli1/2, HIF1α, STAT3, IRF1, TCF4, and NICD or an antagonist of p53 to promote the progression of CRC and HCC. In this review, we summarize the molecular mechanisms of JMJD2D in promoting the progression of CRC and HCC as well as the constructive role of its targeting inhibitors in suppressing tumorigenesis and synergistically enhancing the efficacy of anti-PD-1/PD-L1 immunotherapy.

Transcriptomic and Drug Discovery Analyses Reveal Natural Compounds Targeting the KDM4 Subfamily as Promising Adjuvant Treatments in Cancer

KDM4 proteins are a subfamily of histone demethylases that target the trimethylation of lysines 9 and 36 of histone H3, which are associated with transcriptional repression and elongation respectively. Their deregulation in cancer may lead to chromatin structure alteration and transcriptional defects that could promote malignancy. Despite that KDM4 proteins are promising drug targets in cancer therapy, only a few drugs have been described as inhibitors of these enzymes, while studies on natural compounds as possible inhibitors are still needed. Natural compounds are a major source of biologically active substances and many are known to target epigenetic processes such as DNA methylation and histone deacetylation, making them a rich source for the discovery of new histone demethylase inhibitors. Here, using transcriptomic analyses we determined that the KDM4 family is deregulated and associated with a poor prognosis in multiple neoplastic tissues. Also, by molecular docking and molecular dynamics approaches, we screened the COCONUT database to search for inhibitors of natural origin compared to FDA-approved drugs and DrugBank databases. We found that molecules from natural products presented the best scores in the FRED docking analysis. Molecules with sugars, aromatic rings, and the presence of OH or O- groups favor the interaction with the active site of KDM4 subfamily proteins. Finally, we integrated a protein-protein interaction network to correlate data from transcriptomic analysis and docking screenings to propose FDA-approved drugs that could be used as multitarget therapies or in combination with the potential natural inhibitors of KDM4 enzymes. This study highlights the relevance of the KDM4 family in cancer and proposes natural compounds that could be used as potential therapies.

Comprehensive Analysis of the Transcriptome-Wide m6A Methylation in Mouse Pachytene Spermatocytes and Round Spermatids

Spermatogenesis, an efficient and complex system in male germline development, requires a series of elaborately regulated genetic events in which diploid spermatogonia differentiate into haploid spermatozoa. N6-methyladenosine (m6A) is an important epigenetic RNA modification that occurs during spermatogenesis. ALKBH5 is an m6A eraser and knocking out Alkbh5 increases the level of total m6A methylation and causes male infertility. In this study, comprehensive analyses of MeRIP-seq and RNA-seq data revealed differences between wild-type (WT) and Alkbh5 knockout (KO) mice. In pachytene spermatocytes (PA), 8,151 m6A peaks associated with 9,959 genes were tested from WT and 10,856 m6A peaks associated with 10,016 genes were tested from KO mice. In the round spermatids (RO), 10,271 m6A peaks associated with 10,109 genes were tested from WT mice and 9,559 m6A peaks associated with 10,138 genes were tested from KO mice. The peaks were mainly concentrated in the coding region and the stop codon of the GGAC motif. In addition, enrichment analysis showed significant m6A methylation genes in related pathways in spermatogenesis. Furthermore, we conducted joint analyses of the m6A methylome and RNA transcription, suggesting an m6A regulatory mechanism of gene expression. Finally, seven differentially expressed mRNAs from RNA-seq data in both PA and RO were verified using qPCR. Overall, our study provides new information on m6A modification changes between WT and KO in PA and RO, and may provide new insights into the molecular mechanisms of m6A modification in germ cell development and spermatogenesis.

WDFY1, a WD40 repeat protein, is not essential for spermatogenesis and male fertility in mice

The mouse WD repeat and FYVE domain containing 1 (Wdfy1) gene is located in chromosome 1qC4 and spans over 73.7 kilobases. It encodes a protein of 410-amino acid protein that shares 97.8% amino acid sequence identity with the human WDFY1 protein. However, the expression pattern of WDFY1 in reproductive organs and its function in male fertility remain unknown. In this study, we generated transgenic mice expressing FLAG-Wdfy1-mCherry cDNA driven by the Wdfy1 promoter to clarify the expression of WDFY1. The results showed that WDFY1 is highly expressed in mouse testes and located in the cytoplasm of late pachytene spermatocytes to elongated spermatids. Interestingly, the global Wdfy1 knockout (KO) male mice displayed normal growth, development, and fertility. Further histological analysis of Wdfy1 knockout mouse testes revealed that all spermatogenic cells are present in Wdfy1 KO seminiferous tubules. Together, our data demonstrate that WDFY1 is dispensable for mouse spermatogenesis and male fertility.

Histone demethylase IBM1-mediated meiocyte gene expression ensures meiotic chromosome synapsis and recombination

Histone methylation and demethylation play important roles in plant growth and development, but the involvement of histone demethylation during meiosis is poorly understood. Here we show that disruption of Arabidopsis thaliana INCREASE IN BONSAI METHYLATION 1 (IBM1) causes incomplete synapsis, chromosome entanglement and reduction of recombination during meiosis, leading to sterility. Interestingly, these ibm1 meiotic defects are rescued by mutations in either SUVH4/KYP or CMT3. Using transcriptomic analyses we show that mutation of IBM1 down-regulates thousands of genes expressed in meiocytes, and that expression of about 38% of these genes are restored to wild type levels in ibm1 cmt3 double mutants. Changes in the expression of 437 of these, including the ARABIDOPSIS MEI2-LIKE AML3-5 genes, are correlated with a significant reduction of gene body CHG methylation. Consistently, the aml3 aml4 aml5 triple have defects in synapsis and chromosome entanglement similar to ibm1. Genetic analysis shows that aml3 aml4 aml5 ibm1 quadruple mutants resembles the ibm1 single mutant. Strikingly, over expression of AML5 in ibm1 can partially rescue the ibm1 meiotic defects. Taken together, our results demonstrate that histone demethylase IBM1 is required for meiosis likely via coordinated regulation of meiocyte gene expression during meiosis.

The Diverse Roles of Histone Demethylase KDM4B in Normal and Cancer Development and Progression

Histone methylation status is an important process associated with cell growth, survival, differentiation and gene expression in human diseases. As a member of the KDM4 family, KDM4B specifically targets H1.4K26, H3K9, H3K36, and H4K20, which affects both histone methylation and gene expression. Therefore, KDM4B is often regarded as a key intermediate protein in cellular pathways that plays an important role in growth and development as well as organ differentiation. However, KDM4B is broadly defined as an oncoprotein that plays key roles in processes related to tumorigenesis, including cell proliferation, cell survival, metastasis and so on. In this review, we discuss the diverse roles of KDM4B in contributing to cancer progression and normal developmental processes. Furthermore, we focus on recent studies highlighting the oncogenic functions of KDM4B in various kinds of cancers, which may be a novel therapeutic target for cancer treatment. We also provide a relatively complete report of the progress of research related to KDM4B inhibitors and discuss their potential as therapeutic agents for overcoming cancer.

KDM4 Involvement in Breast Cancer and Possible Therapeutic Approaches

Breast cancer (BC) is the second leading cause of cancer death in women, although recent scientific and technological achievements have led to significant improvements in progression-free disease and overall survival of patients. Genetic mutations and epigenetic modifications play a critical role in deregulating gene expression, leading to uncontrolled cell proliferation and cancer progression. Aberrant histone modifications are one of the most frequent epigenetic mechanisms occurring in cancer. In particular, methylation and demethylation of specific lysine residues alter gene accessibility via histone lysine methyltransferases (KMTs) and histone lysine demethylases (KDMs). The KDM family includes more than 30 members, grouped into six subfamilies and two classes based on their sequency homology and catalytic mechanisms, respectively. Specifically, the KDM4 gene family comprises six members, KDM4A-F, which are associated with oncogene activation, tumor suppressor silencing, alteration of hormone receptor downstream signaling, and chromosomal instability. Blocking the activity of KDM4 enzymes renders them "druggable" targets with therapeutic effects. Several KDM4 inhibitors have already been identified as anticancer drugs in vitro in BC cells. However, no KDM4 inhibitors have as yet entered clinical trials due to a number of issues, including structural similarities between KDM4 members and conservation of the active domain, which makes the discovery of selective inhibitors challenging. Here, we summarize our current knowledge of the molecular functions of KDM4 members in BC, describe currently available KDM4 inhibitors, and discuss their potential use in BC therapy.

Structural and Functional Characterization of a Testicular Long Non-coding RNA (4930463O16Rik) Identified in the Meiotic Arrest of the Mouse Topaz1 -/- Testes

Spermatogenesis involves coordinated processes, including meiosis, to produce functional gametes. We previously reported Topaz1 as a germ cell-specific gene highly conserved in vertebrates. Topaz1 knockout males are sterile with testes that lack haploid germ cells because of meiotic arrest after prophase I. To better characterize Topaz1^–/– testes, we used RNA-sequencing analyses at two different developmental stages (P16 and P18). The absence of TOPAZ1 disturbed the expression of genes involved in microtubule and/or cilium mobility, biological processes required for spermatogenesis. Moreover, a quarter of P18 dysregulated genes are long non-coding RNAs (lncRNAs), and three of them are testis-specific and located in spermatocytes, their expression starting between P11 and P15. The suppression of one of them, 4939463O16Rik, did not alter fertility although sperm parameters were disturbed and sperm concentration fell. The transcriptome of P18-4939463O16Rik^–/– testes was altered and the molecular pathways affected included microtubule-based processes, the regulation of cilium movement and spermatogenesis. The absence of TOPAZ1 protein or 4930463O16Rik produced the same enrichment clusters in mutant testes despite a contrasted phenotype on male fertility. In conclusion, although Topaz1 is essential for the meiosis in male germ cells and regulate the expression of numerous lncRNAs, these studies have identified a Topaz1 regulated lncRNA (4930463O16Rik) that is key for both sperm production and motility.

Knockout of the family with sequence similarity 181, member A (Fam181a) gene does not impair spermatogenesis or male fertility in the mouse

Family with sequence similarity 181 (Fam181 ) is a gene family with two paralogues (Fam181a and Fam181b ) found among vertebrates. Fam181a exhibits dynamic and stage-specific expression during murine embryo development. Furthermore, searching in the National Center for Biotechnology Information database revealed predominant expression of Fam181a in mouse and human testes, implying that it may have essential roles in spermatogenesis. In this study we investigated the invivo function of Fam181a in mouse spermatogenesis and fertility by generating Fam181a -/- mice using clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) 9 genome editing technology. The resulting Fam181a -/- mice exhibited normal growth and development. In addition, the mice were completely fertile, with no obvious differences in the testis-to-bodyweight ratio, epididymal sperm count or sperm motility compared with wild-type mice. Further examination of testicular and epididymal histology of Fam181a -/- mice found an intact seminiferous tubule structure and the presence of all types of germ cells, from spermatogonia to mature spermatozoa, similar to wild-type littermates. Similarly, analysis of meiotic prophase I progression revealed normal populations of each substage of prophase I in Fam181a +/+ and Fam181a -/- testes, suggesting that this gene is dispensable for male fertility. These negative findings will help avoid research overlap, save time and resources and allow researchers to concentrate on genes that are critical for male fertility and spermatogenesis.

Comparative distributions of RSBN1 and methylated histone H4 Lysine 20 in the mouse spermatogenesis

During spermatogenesis, nuclear architecture of male germ cells is dynamically changed and epigenetic modifications, in particular methylation of histones, highly contribute to its regulation as well as differentiation of male germ cells. Although several methyltransferases and demethylases for histone H3 are involved in the regulation of spermatogenesis, roles of either histone H4 lysine 20 (H4K20) methyltransferases or H4K20 demethylases during spermatogenesis still remain to be elucidated. Recently, RSBN1 which is a testis-specific gene expressed in round spermatids was identified as a demethylase for dimethyl H4K20. In this study, therefore, we confirm the demethylase function of RSBN1 and compare distributions between RSBN1 and methylated H4K20 in the seminiferous tubules. Unlike previous report, expression analyses for RSBN1 reveal that RSBN1 is not a testis-specific gene and is expressed not only in round spermatids but also in elongated spermatids. In addition, RSBN1 can demethylate not only dimethyl H4K20 but also trimethyl H4K20 and could convert both dimethyl H4K20 and trimethyl H4K20 into monomethyl H4K20. When distribution pattern of RSBN1 in the seminiferous tubule is compared to that of methylated H4K20, both dimethyl H4K20 and trimethyl H4K20 but not monomethyl H4K20 are disappeared from RSBN1 positive germ cells, suggesting that testis-specific distribution patterns of methylated H4K20 might be constructed by RSBN1. Thus, novel expression and function of RSBN1 could be useful to comprehend epigenetic regulation during spermatogenesis.

Inactivation of testis-specific gene C4orf46 is dispensable for spermatogenesis and fertility in mouse

Several genes have been reported to be involved in spermatogenesis but their functional importance in male fertility is yet needed to be elucidated. Therefore, in current research, we focused to explore the in vivo role of evolutionary conserved and testis-specifically expressed, C4orf46, gene in male mouse fertility and spermatogenesis. The expression profile of C4orf46 is specific to testes and expressed in testes from 7 days of postpartum to onward. Thus, we generated the C4orf46 knockout mice by utilizing CRISPR/Cas9 genome editing technology and examined gene function in spermatogenesis and fertility. Surprisingly, C4orf46 knockout mice were completely fertile, displayed normal testes morphology, however, higher sperm contents were observed in knockout mice compared to wild type (WT) littermates. Subsequently, intact testis histology and architecture of seminiferous tubules were observed in C4orf46 knockout and WT mice. Similarly, sperm morphology and swimming velocity of C4orf46 knockout mice were comparable with the WT littermates. Furthermore, all type of germ cells ranging from spermatogonia to mature spermatozoa were observed in the testes and epididymis sections of C4orf46 knockout mice suggesting that disruption of C4orf46 did not impact spermatogenesis. Moreover, meiotic prophase I progression was normal, and each type of cell population was comparable between knockout and WT mice. Overall, finding from this research indicates that C4orf46 is not an essential gene for fertility in mice. This study will help researchers to avoid the repetition and duplication of efforts, and to explore the genes that are indispensable for spermatogenesis and male fertility.

The KDM4B-CCAR1-MED1 axis is a critical regulator of osteoclast differentiation and bone homeostasis

Bone undergoes a constant and continuous remodeling process that is tightly regulated by the coordinated and sequential actions of bone-resorbing osteoclasts and bone-forming osteoblasts. Recent studies have shown that histone demethylases are implicated in osteoblastogenesis; however, little is known about the role of histone demethylases in osteoclast formation. Here, we identified KDM4B as an epigenetic regulator of osteoclast differentiation. Knockdown of KDM4B significantly blocked the formation of tartrate-resistant acid phosphatase-positive multinucleated cells. Mice with myeloid-specific conditional knockout of KDM4B showed an osteopetrotic phenotype due to osteoclast deficiency. Biochemical analysis revealed that KDM4B physically and functionally associates with CCAR1 and MED1 in a complex. Using genome-wide chromatin immunoprecipitation (ChIP)-sequencing, we revealed that the KDM4B–CCAR1–MED1 complex is localized to the promoters of several osteoclast-related genes upon receptor activator of NF-κB ligand stimulation. We demonstrated that the KDM4B–CCAR1–MED1 signaling axis induces changes in chromatin structure (euchromatinization) near the promoters of osteoclast-related genes through H3K9 demethylation, leading to NF-κB p65 recruitment via a direct interaction between KDM4B and p65. Finally, small molecule inhibition of KDM4B activity impeded bone loss in an ovariectomized mouse model. Taken together, our findings establish KDM4B as a critical regulator of osteoclastogenesis, providing a potential therapeutic target for osteoporosis.

Overexpression of KDM4D promotes acute myeloid leukemia cell development by activating MCL-1

Acute myeloid leukemia (AML) is regarded as a fatal cancer in the world. The overall survival in adult patients with AML is still poor. As lysine demethylases, the KDM4 family is found highly expressed in many kinds of tumors. In this study, we demonstrate that KDM4D is overexpressed in AML and knockdown of KDM4D not only inhibits the proliferation of AML cells, but also induces cell cycle arrest and apoptosis. Furthermore, our research shows that KDM4D can regulate the expression of MCL-1 by demethylating H3K9me3 at the promoter region in AML cells. Besides, we find that high expression of KDM4D is correlated with poor overall survival in AML patients. Taken together, our study demonstrated that KDM4D can promote MCL-1 expression in AML and may serve as a novel target for the treatment of AML.

Dynamic Histone H3 Modifications Regulate Meiosis Initiation via Respiration

Meiosis is essential for genetic stability and diversity during sexual reproduction in most eukaryotes. Chromatin structure and gene expression are drastically changed during meiosis, and various histone modifications have been reported to participate in this unique process. However, the dynamic of histone modifications during meiosis is still not well investigated. Here, by using multiple reaction monitoring (MRM) based LC-MS/MS, we detected dynamic changes of histone H3 lysine post-translational modifications (PTMs). We firstly quantified the precise percentage of H3 modifications on different lysine sites during mouse and yeast meiosis, and found H3 acetylation and methylation were dramatically changed. To further study the potential functions of H3 acetylation and methylation in meiosis, we performed histone H3 lysine mutant screening in yeast, and found that yeast strains lacking H3K18 acetylation (H3K18ac) failed to initiate meiosis due to insufficient IME1 expression. Further studies showed that the absence of H3K18ac impaired respiration, leading to the reduction of Rim101p, which further upregulated a negative regulator of IME1 transcription, Smp1p. Together, our studies reveal a novel meiosis initiation pathway mediated by histone H3 modifications.

Roles of HIF and 2-Oxoglutarate-Dependent Dioxygenases in Controlling Gene Expression in Hypoxia

Simple Summary

Hypoxia—reduction in oxygen availability—plays key roles in both physiological and pathological processes. Given the importance of oxygen for cell and organism viability, mechanisms to sense and respond to hypoxia are in place. A variety of enzymes utilise molecular oxygen, but of particular importance to oxygen sensing are the 2-oxoglutarate (2-OG) dependent dioxygenases (2-OGDs). Of these, Prolyl-hydroxylases have long been recognised to control the levels and function of Hypoxia Inducible Factor (HIF), a master transcriptional regulator in hypoxia, via their hydroxylase activity. However, recent studies are revealing that such dioxygenases are involved in almost all aspects of gene regulation, including chromatin organisation, transcription and translation.

Abstract

Hypoxia—reduction in oxygen availability—plays key roles in both physiological and pathological processes. Given the importance of oxygen for cell and organism viability, mechanisms to sense and respond to hypoxia are in place. A variety of enzymes utilise molecular oxygen, but of particular importance to oxygen sensing are the 2-oxoglutarate (2-OG) dependent dioxygenases (2-OGDs). Of these, Prolyl-hydroxylases have long been recognised to control the levels and function of Hypoxia Inducible Factor (HIF), a master transcriptional regulator in hypoxia, via their hydroxylase activity. However, recent studies are revealing that dioxygenases are involved in almost all aspects of gene regulation, including chromatin organisation, transcription and translation. We highlight the relevance of HIF and 2-OGDs in the control of gene expression in response to hypoxia and their relevance to human biology and health.

The landscape of long noncoding RNA-involved and tumor-specific fusions across various cancers

The majority of the human genome encodes long noncoding RNA (lncRNA) genes, critical regulators of various cellular processes, which largely outnumber protein-coding genes. However, lncRNA-involved fusions have not been surveyed and characterized yet. Here, we present a systematic study of the lncRNA fusion landscape across cancer types and identify >30 000 high-confidence tumor-specific lncRNA fusions (using 8284 tumor and 6946 normal samples). Fusions positively correlated with DNA damage and cancer stemness and were specifically low in microsatellite instable (MSI)-High or virus-infected tumors. Moreover, fusions distribute differently among cancer molecular subtypes, but with shared enrichment in tumors that are microsatellite stable (MSS), with high somatic copy number alterations (SCNA), and with poor survival. Importantly, we find a potentially new mechanism, mediated by enhancer RNAs (eRNA), which generates secondary fusions that form densely connected fusion networks with many fusion hubs targeted by FDA-approved drugs. Finally, we experimentally validate functions of two tumor-promoting chimeric proteins derived from mRNA-lncRNA fusions, KDM4B-G039927 and EPS15L1-lncOR7C2-1. The EPS15L1 fusion protein may regulate (Gasdermin E) GSDME, critical in pyroptosis and anti-tumor immunity. Our study completes the fusion landscape in cancers, sheds light on fusion mechanisms, and enriches lncRNA functions in tumorigenesis and cancer progression.

Multiple Effects of Ascorbic Acid against Chronic Diseases: Updated Evidence from Preclinical and Clinical Studies

Severe disease commonly manifests as a systemic inflammatory process. Inflammation is associated withthe enhanced production of reactive oxygen and nitrogen species and with a marked reduction in the plasma concentrations of protective antioxidant molecules. This imbalance gives rise to oxidative stress, which is greater in patients with more severe conditions such as sepsis, cancer, cardiovascular disease, acute respiratory distress syndrome, and burns. In these patients, oxidative stress can trigger cell, tissue, and organ damage, thus increasing morbidity and mortality. Ascorbic acid (ASC) is a key nutrient thatserves as an antioxidant and a cofactor for numerous enzymatic reactions. However, humans, unlike most mammals, are unable to synthesize it. Consequently, ASC must be obtained through dietary sources, especially fresh fruit and vegetables. The value of administering exogenous micronutrients, to reestablish antioxidant concentrations in patients with severe disease, has been recognized for decades. Despite the suggestion that ASC supplementation may reduce oxidative stress and prevent several chronic conditions, few large, randomized clinical trials have tested it in patients with severe illness. This article reviews the recent literature on the pharmacological profile of ASC and the role of its supplementation in critically ill patients.

Spermatogenesis is normal in Tex33 knockout mice

Testis expressed gene 33 (Tex33) is a recently reported testis-specific gene and it is evolutionarily conserved in vertebrates. The Tex33 expression is found in cytoplasm of round spermatids in Mus musculus. However, the in vivo function of Tex33 remains unknown. In this study, we made a 62bp in frame deletion on Exon2 of Tex33 gene by CRISPR/Cas9 in C57B/L6 mouse, which cause frame shift mutation of Tex33 gene. Tex33^-/-adult male were fertile, and there is no significant change on litter size compared with male wildtype (Tex33^+/+) adult. Besides, no overt differences were found in testis/body weight ratios, testicular/epididymal tissue morphology, sperm counts, sperm morphology and spermatozoa motility in adult Tex33^-/-male mice (N = 3), in comparison with Tex33^+/+ adult (N = 3). TUNEL assay also indicates the germ cells apoptosis ratio was not significantly changed in adult Tex33^-/- adult male mouse testis (N = 3), compared with adult Tex33^+/+ male (N = 3). Importantly, the first wave of elongating spermatids formation happens in 5w old mice. We find that the first wave of spermiogenesis is not disrupted in both 5-week-old Tex33^+/+ and Tex33^-/-male mouse testes and three hallmarks of spermatogenesis, PLZF,γ-H2AX and TNP1, are all detectable in seminiferous tubule. All results indicate that Tex33 is a redundant gene to spermatogenesis. This study can help other researchers avoid repetitive works on redundant genes.

Emerging of lysine demethylases (KDMs): From pathophysiological insights to novel therapeutic opportunities

In recent years, there have been remarkable scientific advancements in the understanding of lysine demethylases (KDMs) because of their demethylation of diverse substrates, including nucleic acids and proteins. Novel structural architectures, physiological roles in the gene expression regulation, and ability to modify protein functions made KDMs the topic of interest in biomedical research. These structural diversities allow them to exert their function either alone or in complex with numerous other bio-macromolecules. Impressive number of studies have demonstrated that KDMs are localized dynamically across the cellular and tissue microenvironment. Their dysregulation is often associated with human diseases, such as cancer, immune disorders, neurological disorders, and developmental abnormalities. Advancements in the knowledge of the underlying biochemistry and disease associations have led to the development of a series of modulators and technical compounds. Given the distinct biophysical and biochemical properties of KDMs, in this review we have focused on advances related to the structure, function, disease association, and therapeutic targeting of KDMs highlighting improvements in both the specificity and efficacy of KDM modulation.

Comprehensive histochemical profiles of histone modification in male germline cells during meiosis and spermiogenesis: Comparison of young and aged testes in mice

Human epidemiological studies have shown that paternal aging as one of the risk factors for neurodevelopmental disorders, such as autism, in offspring. A recent study has suggested that factors other than de novo mutations due to aging can influence the biology of offspring. Here, we focused on epigenetic alterations in sperm that can influence developmental programs in offspring. In this study, we qualitatively and semiquantitatively evaluated histone modification patterns in male germline cells throughout spermatogenesis based on immunostaining of testes taken from young (3 months old) and aged (12 months old) mice. Although localization patterns were not obviously changed between young and aged testes, some histone modification showed differences in their intensity. Among histone modifications that repress gene expression, histone H3 lysine 9 trimethylation (H3K9me3) was decreased in the male germline cells of the aged testis, while H3K27me2/3 was increased. The intensity of H3K27 acetylation (ac), an active mark, was lower/higher depending on the stages in the aged testis. Interestingly, H3K27ac was detected on the putative sex chromosomes of round spermatids, while other chromosomes were occupied by a repressive mark, H3K27me3. Among other histone modifications that activate gene expression, H3K4me2 was drastically decreased in the male germline cells of the aged testis. In contrast, H3K79me3 was increased in M-phase spermatocytes, where it accumulates on the sex chromosomes. Therefore, aging induced alterations in the amount of histone modifications and in the differences of patterns for each modification. Moreover, histone modifications on the sex chromosomes and on other chromosomes seems to be differentially regulated by aging. These findings will help elucidate the epigenetic mechanisms underlying the influence of paternal aging on offspring development.

Expression profiling of the Kdm genes in scallop Patinopecten yessoensis suggests involvement of histone demethylation in regulation of early development and gametogenesis

Histone demethylation modification is an important means of gene expression regulation and is widely involved in biological processes such as animal reproduction and development. Histone lysine demethylases (Kdm) plays an important role in the demethylation of histones. To understand the role of histone demethylation in scallops, we identified the Kdm gene family of the Yesso scallop Patinopecten yessoensis, and analyzed its expression during the gonad and early development. The results showed that the P. yessoensis has a complete Kdm family including seventeen members that belong to sixteen subfamilies (Hif1an, Hspbap1, Jarid2, Jmjd4, Jmjd6, Jmjd7, Jmjd8, Kdm1, Kdm2, Kdm3, Kdm4, Kdm5, Kdm6, Kdm7, Kdm8 and Kdm9). The Kdm genes showed five different expression patterns in the early development of scallop, with some of them (e.g. Jmjd7, Jmjd8 and Kdm8) being highly expressed in only one or two stage and the others (e.g. Kdm1A, Kdm9, Jmjd4 and Jmjd6) in several consecutive stages. During gonadal development, the Kdm genes also display various expression patterns. Some genes (e.g. Kdm2, Kdm4 and Jmjd7) display preferential expression in the testis, and the others have no obvious sex bias but show stage preference (resting, proliferative, growing or maturation stage). These results suggest that various histone demethylation modifications (e.g. H3K4, H3K9 and H3K27) may participate in the regulation of gametogenesis and early development of Yesso scallop. It will facilitate a better understanding of the epigenetic contributions to mollusk development.

IL-6 and IL-8 are involved in JMJD2A-regulated malignancy of ovarian cancer cells

Emerging evidence shows that histone modification and its related regulators are involved in the progression and chemoresistance of ovarian cancer (OC) cells. Our present study found that the expression of Jumonji C domain-containing 2A (JMJD2A), while not JMJD2B or JMJD2C, is increased in OC cells and tissues as compared with that in their corresponding controls. Knockdown of JMJD2A can decrease proliferation while increase cisplatin (CDDP) sensitivity of OC cells. By screening the expression of cytokines involved in the progression of ovarian cancer, we found that knockdown of JMJD2A can inhibit the expression of interleukin-6 (IL-6) and IL-8 in ovarian cancer cells. Recombinant IL-6 (rIL-6) and rIL-8 can attenuate si-JMJD2A-suppressed malignancy of OC cells. Mechanistically, JMJD2A can directly bind with the promoter of IL-6 to trigger its transcription. For IL-8, JMJD2A can increase it mRNA stability in OC cells. Collectively, we revealed that JMJD2A can trigger the malignancy of OC cells via upregulation of IL-6 and IL-8. It suggested that JMJD2A might be a potential target for OC treatment and therapy.

Histone Post-Translational Modifications and CircRNAs in Mouse and Human Spermatozoa: Potential Epigenetic Marks to Assess Human Sperm Quality

Spermatozoa (SPZ) are motile cells, characterized by a cargo of epigenetic information including histone post-translational modifications (histone PTMs) and non-coding RNAs. Specific histone PTMs are present in developing germ cells, with a key role in spermatogenic events such as self-renewal and commitment of spermatogonia (SPG), meiotic recombination, nuclear condensation in spermatids (SPT). Nuclear condensation is related to chromatin remodeling events and requires a massive histone-to-protamine exchange. After this event a small percentage of chromatin is condensed by histones and SPZ contain nucleoprotamines and a small fraction of nucleohistone chromatin carrying a landascape of histone PTMs. Circular RNAs (circRNAs), a new class of non-coding RNAs, characterized by a nonlinear back-spliced junction, able to play as microRNA (miRNA) sponges, protein scaffolds and translation templates, have been recently characterized in both human and mouse SPZ. Since their abundance in eukaryote tissues, it is challenging to deepen their biological function, especially in the field of reproduction. Here we review the critical role of histone PTMs in male germ cells and the profile of circRNAs in mouse and human SPZ. Furthermore, we discuss their suggested role as novel epigenetic biomarkers to assess sperm quality and improve artificial insemination procedure.

The KDM4/JMJD2 histone demethylases are required for hematopoietic stem cell maintenance

KDM4/JMJD2 are H3K9- and H3K36-specific demethylases, which are considered promising therapeutic targets for the treatment of acute myeloid leukemia (AML) harboring MLL translocations. Here, we investigate the long-term effects of depleting KDM4 activity on normal hematopoiesis to probe potential side effects of continuous inhibition of these enzymes. Utilizing conditional Kdm4a/Kdm4b/Kdm4c triple-knockout mice, we show that KDM4 activity is required for hematopoietic stem cell (HSC) maintenance in vivo. The knockout of the KDM4 demethylases leads to accumulation of H3K9me3 on transcription start sites and the corresponding downregulation of expression of several genes in HSCs. We show that 2 of these genes, Taf1b and Nom1, are essential for the maintenance of hematopoietic cells. Taken together, our results show that the KDM4 demethylases are required for the expression of genes essential for the long-term maintenance of normal hematopoiesis.

Enhanced histone H3K9 tri-methylation suppresses steroidogenesis in rat testis chronically exposed to arsenic

Arsenic poses a profound health risk including male reproductive dysfunction upon prolonged exposure. Histone methylation is an important epigenetic driver; however, its role in arsenic- induced steroidogenic pathogenesis remains obscure. In current study, we investigated the effect of histone H3K9 tri-methylation (H3K9me3) on expression pattern of steroidogenic genes in rat testis after long-term arsenic exposure. Our results revealed that arsenic exposure down-regulated the mRNA expressions of all studied steroidogenic genes (Lhr, Star, P450scc, Hsd3b, Cyp17a1, Hsd17b and Arom). Moreover, arsenic significantly increased the H3K9me3 level in rat testis. The plausible explanation of increased H3K9me3 was attributable to the up-regulation of histone H3K9me3 methyltransferase, Suv39h1 and down-regulation of demethylase, Jmjd2a. Since H3K9me3 activation leads to gene repression, we further investigated whether the down-regulation of steroidogenic genes was ascribed to the increased H3K9me3 level. To elucidate this, we determined the H3K9me3 levels in steroidogenic gene promoters, which also showed significant increase of H3K9me3 in the investigated regions after arsenic exposure. In conclusion, arsenic exposure suppressed the steroidogenic gene expression by activating H3K9me3 status, which contributed to steroidogenic inhibition in rat testis.

KDM4B: A Nail for Every Hammer?

Epigenetic changes are well-established contributors to cancer progression and normal developmental processes. The reversible modification of histones plays a central role in regulating the nuclear processes of gene transcription, DNA replication, and DNA repair. The KDM4 family of Jumonj domain histone demethylases specifically target di- and tri-methylated lysine 9 on histone H3 (H3K9me3), removing a modification central to defining heterochromatin and gene repression. KDM4 enzymes are generally over-expressed in cancers, making them compelling targets for study and therapeutic inhibition. One of these family members, KDM4B, is especially interesting due to its regulation by multiple cellular stimuli, including DNA damage, steroid hormones, and hypoxia. In this review, we discuss what is known about the regulation of KDM4B in response to the cellular environment, and how this context-dependent expression may be translated into specific biological consequences in cancer and reproductive biology.

An ancient germ cell-specific RNA-binding protein protects the germline from cryptic splice site poisoning

Male germ cells of all placental mammals express an ancient nuclear RNA binding protein of unknown function called RBMXL2. Here we find that deletion of the retrogene encoding RBMXL2 blocks spermatogenesis. Transcriptome analyses of age-matched deletion mice show that RBMXL2 controls splicing patterns during meiosis. In particular, RBMXL2 represses the selection of aberrant splice sites and the insertion of cryptic and premature terminal exons. Our data suggest a Rbmxl2 retrogene has been conserved across mammals as part of a splicing control mechanism that is fundamentally important to germ cell biology. We propose that this mechanism is essential to meiosis because it buffers the high ambient concentrations of splicing activators, thereby preventing poisoning of key transcripts and disruption to gene expression by aberrant splice site selection.

In humans and other mammals, a sperm from a male fuses with an egg cell from a female to produce an embryo that may ultimately grow into a new individual. Sperm and egg cells are made when certain cells in the body divide in a process called meiosis. Many proteins are required for meiosis to happen and these proteins are made using instructions provided by genes, which are made of a molecule called DNA.

The DNA within a gene is transcribed to make molecules of ribonucleic acid (or RNA for short). The cell then modifies many of these RNAs in a process called splicing before using them as templates to make proteins. During splicing, segments of RNA known as introns are discarded and other segments termed exons are joined together. Some exons may also be removed from RNAs in different combinations to create different proteins from the same gene.

A protein called RBMXL2 is able to bind to RNA molecules and is only made during and after meiosis in humans and most other mammals. RBMXL2 can also bind to other proteins that are known to be involved in controlling splicing of RNAs, but its role in splicing remains unclear.

To address this question, Ehrmann et al. studied the gene that encodes the RBMXL2 protein in mice. Removing this gene prevented male mice from being able to make sperm. Further experiments using a technique called RNA sequencing showed that the RBMXL2 protein helps to ensure that splicing happens correctly by preventing bits of exons and introns in mouse genes from being rearranged. These findings suggest that the gene encoding RBMXL2 is part of a splicing control mechanism that is important for making sperm and egg cells.

The work of Ehrmann et al. could eventually help some couples understand why they have problems conceiving children. Male infertility is poorly understood, and not knowing its causes can harm the mental health of affected men. Furthermore, these findings may help researchers to understand the role of a closely related protein called RBMY that has also been linked to infertility in men, but is much more difficult to study.

Molecular Mechanisms of Apical Periodontitis: Emerging Role of Epigenetic Regulators

Conventional root canal therapies yield high success rates. The treatment outcomes are negatively affected by the presence of apical periodontitis (AP), which reflects active root canal infection and inflammatory responses. Also, cross-sectional studies revealed surprisingly high prevalence of AP in the general population, especially in those with prior endodontic treatments. Hence, AP is an ongoing disease entity in endodontics that needs further understanding of the pathogenesis and disease progression. The current Chapter will discuss the basic mechanisms of AP with emphasis on emerging role of epigenetic regulators in regulation of inflammatory mediators.

Cooperation between ETS variant 2 and Jumonji domain‑containing 2 histone demethylases

The E26 transformation-specific (ETS) variant 2 (ETV2) protein, also designated as ETS-related 71, is a member of the ETS transcription factor family and is essential for blood and vascular development in the embryo. The role of ETV2 in cancer has not yet been investigated. In the present study, the expression of ETV2 mRNA was identified in a variety of tumor types, including prostate carcinoma. In addition, ETV2 gene amplification was identified in several types of cancer, suggesting that ETV2 plays an oncogenic role in tumorigenesis. It was demonstrated that ETV2 forms complexes with two histone demethylases: Jumonji domain-containing (JMJD)2A and JMJD2D; JMJD2A has been previously reported as a driver of prostate cancer development. In the present study, it was reported that ETV2 exhibited the potential to stimulate the promoters of matrix metalloproteinases (MMPs), including MMP1 and MMP7, within LNCaP prostate cancer cells. JMJD2A and JMJD2D could synergize with ETV2 to activate the MMP1 promoter, whereas only JMJD2A stimulated the MMP7 promoter in cooperation with ETV2. Furthermore, ETV2 expression was positively associated with JMJD2A and JMJD2D mRNA levels in neuroendocrine prostate tumors, in which an ETV2 gene amplification rate of 17.8% was identified. Collectively, the results of the present study indicated that ETV2, JMJD2A and JMJD2D may jointly promote tumorigenesis, particularly neuroendocrine prostate tumors. In addition, the interaction with the JMJD2A and JMJD2D epigenetic regulators may be important in the ability of ETV2 to reprogram cells, modulate normal and cancer stem cells, and affect spermatogenesis.

MAFB is dispensable for the fetal testis morphogenesis and the maintenance of spermatogenesis in adult mice

The transcription factor MAFB is an important regulator of the development and differentiation of various organs and tissues. Previous studies have shown that MAFB is expressed in embryonic and adult mouse testes and is expected to act as the downstream target of retinoic acid (RA) to initiate spermatogenesis. However, its exact localization and function remain unclear. Here, we localized MAFB expression in embryonic and adult testes and analyzed its gene function using Mafb-deficient mice. We found that MAFB and c-MAF are the only large MAF transcription factors expressed in testes, while MAFA and NRL are not. MAFB was localized in Leydig and Sertoli cells at embryonic day (E) 18.5 but in Leydig cells, Sertoli cells, and pachytene spermatocytes in adults. Mafb-deficient testes at E18.5 showed fully formed seminiferous tubules with no abnormal structure or differences in testicular somatic cell numbers compared with those of control wild-type mice. Additionally, the expression levels of genes related to development and function of testicular cells were unchanged between genotypes. In adults, the expression of MAFB in Sertoli cells was shown to be stage specific and induced by RA. By generating Mafb^fl/fl CAG-CreER^™ (Mafb-cKO) mice, in which Cre recombinase was activated upon tamoxifen treatment, we found that the neonatal cKO mice died shortly upon Mafb deletion, but adult cKO mice were alive upon deletion. Adult cKO mice were fertile, and spermatogenesis maintenance was normal, as indicated by histological analysis, hormone levels, and germ cell stage-specific markers. Moreover, there were no differences in the proportion of seminiferous stages between cKO mice and controls. However, RNA-Seq analysis of cKO Sertoli cells revealed that the down-regulated genes were related to immune function and phagocytosis activity but not spermatogenesis. In conclusion, we found that MAFB is dispensable for fetal testis morphogenesis and spermatogenesis maintenance in adult mice, despite the significant gene expression in different cell types, but MAFB might be critical for phagocytosis activity of Sertoli cells.

Estrogen, through estrogen receptor 1, regulates histone modifications and chromatin remodeling during spermatogenesis in adult rats

Estrogen receptors (ESR1 and ESR2) play crucial roles in various processes during spermatogenesis. To elucidate individual roles of ESRs in male fertility, we developed in vivo selective ESR agonist administration models. Adult male rats treated with ESR1 and ESR2 agonist for 60 days show spermatogenic defects leading to reduced sperm counts and fertility. While studying epigenetic changes in the male germ line that could have affected fertility, we earlier observed a decrease in DNA methylation and its machinery upon ESR2 agonist treatment. Here, we explored the effects on histone modifications, which could contribute to decreased male fertility upon ESR agonist administration. ESR1 agonist treatment affected testicular levels of histone modifications associated with active and repressed chromatin states, along with heterochromatin marks. This was concomitant with deregulation of corresponding histone modifying enzymes in the testis. In addition, there was increased retention of histones along with protamine deficiency in the caudal spermatozoa after ESR1 agonist treatment. This could be due to the observed decrease in several chromatin remodeling proteins implicated in mediating histone-to-protamine exchange during spermiogenesis. The activating and repressing histone marks in spermatozoa, which play a critical role in early embryo development, were deregulated after both the ESR agonist treatments. Together, these epigenetic defects in the male germ line could affect the spermatozoa quality and lead to the observed decrease in fertility. Our results thus highlight the importance of ESRs in regulating different epigenetic processes during spermatogenesis, which are crucial for male fertility.

Systematic discovery of genetic modulation by Jumonji histone demethylases in Drosophila

Jumonji (JmjC) domain proteins influence gene expression and chromatin organization by way of histone demethylation, which provides a means to regulate the activity of genes across the genome. JmjC proteins have been associated with many human diseases including various cancers, developmental and neurological disorders, however, the shared biology and possible common contribution to organismal development and tissue homeostasis of all JmjC proteins remains unclear. Here, we systematically tested the function of all 13 Drosophila JmjC genes. Generation of molecularly defined null mutants revealed that loss of 8 out of 13 JmjC genes modify position effect variegation (PEV) phenotypes, consistent with their ascribed role in regulating chromatin organization. However, most JmjC genes do not critically regulate development, as 10 members are viable and fertile with no obvious developmental defects. Rather, we find that different JmjC mutants specifically alter the phenotypic outcomes in various sensitized genetic backgrounds. Our data demonstrate that, rather than controlling essential gene expression programs, Drosophila JmjC proteins generally act to “fine-tune” different biological processes.

Discovery of pyrazolo[1,5-a]pyrimidine-3-carbonitrile derivatives as a new class of histone lysine demethylase 4D (KDM4D) inhibitors

Herein we report the discovery of a series of new small molecule inhibitors of histone lysine demethylase 4D (KDM4D). Molecular docking was first performed to screen for new KDM4D inhibitors from various chemical databases. Two hit compounds were retrieved. Further structural optimization and structure-activity relationship (SAR) analysis were carried out to the more selective one, compound 2, which led to the discovery of several new KDM4D inhibitors. Among them, compound 10r is the most potent one with an IC₅₀ value of 0.41±0.03μM against KDM4D. Overall, compound 10r could be taken as a good lead compound for further studies.

Epigenetically repressing human cytomegalovirus lytic infection and reactivation from latency in THP-1 model by targeting H3K9 and H3K27 histone demethylases

Human Cytomegalovirus (hCMV) infects a broad range of the population and establishes life-long latency in the infected individuals. Periodically the latently infected virus can reactivate and becomes a significant cause of morbidity and mortality in immunocompromised individuals. In latent infection, the viral genome is suppressed in a heterochromatic state and viral gene transcription is silenced. Upon reactivation, the repressive chromatin is remodeled to an active form, allowing viral lytic gene transcription, initiated by the expression of viral Immediate Early (IE) genes. During this process, a number of histone modification enzymes, including histone demethylases (HDMs), play important roles in driving IE expression, but the mechanisms involved are not fully understood. To get a better understanding of these mechanisms, we focused on two HDMs, KDM4 and KDM6, which reverse the repressive histone H3-lysine 9 and lysine 27 methylation, respectively. Our studies show that in lytic infection, both demethylases are important in the activation of viral IE gene expression. Simultaneous disruption of both via genetic or chemical methods leads to severely impaired viral IE gene expression and viral replication. Additionally, in an experimental latency-reactivation model in THP-1 cells, the KDM6 family member JMJD3 is induced upon viral reactivation and its knockdown resulted in reduced IE gene transcription. These findings suggest pharmacological inhibition of these HDMs may potentially block hCMV lytic infection and reactivation, and control the viral infection associated diseases, which are of significant unmet medical needs.