Knockout of the Histone Demethylase Kdm3b Decreases Spermatogenesis and Impairs Male Sexual Behaviors

Kdm3b is a JmjC domain-containing histone H3 (H3) demethylase and its physiological functions are largely unknown. In this study, we found that Kdm3b protein is highly expressed in multiple cell types in the mouse testes, including Leydig cells, Sertoli cells, spermatogonia and spermatocytes at different differentiation stages. We also observed Kdm3b protein in the epithelial cells of the caput epididymis, prostate and seminal vesicle. Breeding tests revealed that the number of pups produced by the breeding pairs with Kdm3b knockout (Kdm3bKO) males and wild type (WT) females was reduced 68% because of the decreased number of litters when compared with the breeding pairs with WT males and females. Further analysis demonstrated that Kdm3bKO male mice produced 44% fewer number of mature sperm in their cauda epididymides, displaying significantly reduced sperm motility. No significant differences in the circulating concentration of testosterone and the expression levels of androgen receptor and its representative target genes in the testis were observed. However, the circulating levels of 17β-estradiol, a modulator of sperm maturation and male sexual behaviors, was markedly reduced in Kdm3bKO male mice. Strikingly, abrogation of Kdm3b in male mice significantly increased the latencies to mount, intromit and ejaculate and decreased the number of mounts and intromissions, largely due to their loss of interest in female odors. These findings indicate that Kdm3b is required for normal spermatogenesis and sexual behaviors in male mice.     

Kdm4b Histone Demethylase Is a DNA Damage Response Protein and Confers a Survival Advantage following γ-Irradiation

DNA damage evokes a complex and highly coordinated DNA damage response (DDR) that is integral to the suppression of genomic instability. Double-strand breaks (DSBs) are considered the most deleterious form damage. Evidence suggests that trimethylation of histone H3 lysine 9 (H3K9me3) presents a barrier to DSB repair. Also, global levels of histone methylation are clinically predictive for several tumor types. Therefore, demethylation of H3K9 may be an important step in the repair of DSBs. The KDM4 subfamily of demethylases removes H3K9 tri- and dimethylation and contributes to the regulation of cellular differentiation and proliferation; mutation or aberrant expression of KDM4 proteins has been identified in several human tumors. We hypothesize that members of the KDM4 subfamily may be components of the DDR. We found that Kdm4b-enhanced GFP (EGFP) and KDM4D-EGFP were recruited rapidly to DNA damage induced by laser micro-irradiation. Focusing on the clinically relevant Kdm4b, we found that recruitment was dependent on poly(ADP-ribose) polymerase 1 activity as well as Kdm4b demethylase activity. The Kdm4 proteins did not measurably accumulate at γ-irradiation-induced γH2AX foci. Nevertheless, increased levels of Kdm4b were associated with decreased numbers of γH2AX foci 6 h after irradiation as well as increased cell survival. Finally, we found that levels of H3K9me2 and H3K9me3 were decreased at early time points after 2 gray of γ-irradiation. Taken together, these data demonstrate that Kdm4b is a DDR protein and that overexpression of Kdm4b may contribute to the failure of anti-cancer therapy that relies on the induction of DNA damage.     

Dynamic patterns of histone H3 lysine 4 methyltransferases and demethylases during mouse preimplantation development

Extensive and dynamic chromatin remodeling occurs after fertilization, including DNA methylation and histone modifications. These changes underlie the transition from gametic to embryonic chromatin and are thought to facilitate early embryonic development. Histone H3 lysine 4 methylation (H3K4me) is an important epigenetic mechanism that associates with gene-specific activation and functions in development. However, dynamic regulation of H3K4me during early embryonic development remains unclear. Herein, the authors examined the dynamic changes of H3K4me and its key regulators (Ash1l, Ash2l, Kmt2a, Kmt2b, Kmt2c, Setd1a, Setd7, Kdm1a, Kdm1b, Kdm5a, Kdm5b, Kdm5c, and Kdm5d) in mouse oocytes and preimplantation embryos. An increase in levels of H3K4me2 and me3 was observed at the one- to two-cell stages (P?P?P?相似文献   

Kdm6a suppresses the alternative activation of macrophages and impairs energy expenditure in obesity

Histone lysine demethylase 6a (Kdm6a) mediates the removal of repressive trimethylation from histone H3 lysine 27 (H3K27me3) to activate target gene expression. Obesity is associated with metabolic inflammation, and adipose tissue macrophages (ATMs) are key players orchestrating metabolic inflammation. However, it is still unclear whether the Kdm6a pathway in ATMs regulates energy homeostasis. Here, we identified Kdm6a as a critical epigenetic switch that modulates macrophage polarisation and further disrupts energy balance. Myeloid-specific Kdm6a knockout in Kdm6a^F/Y;Lyz2-Cre mice significantly reversed the high-fat diet (HFD)-induced M1–M2 imbalance in white adipose tissue (WAT) and blocked HFD-induced obesity. The brown adipose tissue (BAT) activity, WAT browning and energy expenditure were significantly increased in Kdm6a^F/Y;Lyz2-Cre mice. Furthermore, Kdm6a regulated the Ire1α expression in a demethylase activity-dependent manner and augmented the M2 polarisation of macrophages. Macrophage with higher Kdm6a significantly promotes adipogenesis in white adipocyte and inhibits thermogenesis in beige adipocytes. These results suggest that the Kdm6a in macrophages drives obesity and metabolic syndrome by impairing BAT activity and WAT differentiation.Subject terms: Interleukins, Epigenetics     

Kdm2a deficiency in macrophages enhances thermogenesis to protect mice against HFD-induced obesity by enhancing H3K36me2 at the Pparg locus

Kdm2a catalyzes H3K36me2 demethylation to play an intriguing epigenetic regulatory role in cell proliferation, differentiation, and apoptosis. Herein we found that myeloid-specific knockout of Kdm2a (LysM-Cre-Kdm2a^f/f, Kdm2a^−/−) promoted macrophage M2 program by reprograming metabolic homeostasis through enhancing fatty acid uptake and lipolysis. Kdm2a^−/− increased H3K36me2 levels at the Pparg locus along with augmented chromatin accessibility and Stat6 recruitment, which rendered macrophages with preferential M2 polarization. Therefore, the Kdm2a^−/− mice were highly protected from high-fat diet (HFD)-induced obesity, insulin resistance, and hepatic steatosis, and featured by the reduced accumulation of adipose tissue macrophages and repressed chronic inflammation following HFD challenge. Particularly, Kdm2a^−/− macrophages provided a microenvironment in favor of thermogenesis. Upon HFD or cold challenge, the Kdm2a^−/− mice manifested higher capacity for inducing adipose browning and beiging to promote energy expenditure. Collectively, our findings demonstrate the importance of Kdm2a-mediated H3K36 demethylation in orchestrating macrophage polarization, providing novel insight that targeting Kdm2a in macrophages could be a viable therapeutic approach against obesity and insulin resistance.Subject terms: Chronic inflammation, Histone post-translational modifications, Epigenetics, Endocrine system and metabolic diseases     

Contrasting effects of IGF binding protein-3 expression in mammary tumor cells and the tumor microenvironment

IGFBP-3 has both stimulatory and inhibitory effects on cancer progression. The growth of EO771 mammary carcinoma cells as syngeneic tumors in C57BL/6 mice is reduced in Igfbp3-null (BP3KO) mice, suggesting that systemic IGFBP-3 enhances tumor progression. In this study we assessed the growth of EO771 cells expressing human IGFBP-3 in BP3KO mice. Cells expressing hIGFBP-3 showed decreased proliferation in vitro and increased levels of IGF-1 receptor (IGF1R) protein but not mRNA, consistent with sequestration of endogenous IGF by IGFBP-3. The growth rate of these cells was restored by exposure to IGF-1 or analogues with reduced affinity for IGFBP-3 (long Arg³-IGF-1) or IGF1R (Leu²⁴-IGF-1). In EO771 cells implanted orthotopically into mice, hIGFBP-3 expression by the cells inhibited tumor establishment in BP3KO but not wild-type mice. For tumors that successfully established, final weight was not affected significantly by hIGFBP-3 expression. However, final tumor weight was inversely related to intratumoral T cell counts, and sera from BP3KO mice with tumors showed low-titer immunoreactivity against IGFBP-3. The contrasting effects on tumor establishment and progression of IGFBP-3 expressed by mammary carcinoma cells, compared to systemic stromal and circulating IGFBP-3, highlights the complexity of growth regulation by IGFBP-3 in mammary tumors.     

Multimerization and H3K9me3 Binding Are Required for CDYL1b Heterochromatin Association

Proteins containing defined recognition modules mediate readout and translation of histone modifications. These factors are thought to initiate downstream signaling events regulating chromatin structure and function. We identified CDYL1 as an interaction partner of histone H3 trimethylated on lysine 9 (H3K9me3). CDYL1 belongs to a family of chromodomain factors found in vertebrates. We show that three different splicing variants of CDYL1, a, b, and c, are differentially expressed in various tissues with CDYL1b being the most abundant variant. Although all three splicing variants share a common C-terminal enoyl-CoA hydratase-like domain, only CDYL1b contains a functional chromodomain implicated in H3K9me3 binding. A splicing event introducing an N-terminal extension right at the beginning of the chromodomain of CDYL1a inactivates its chromodomain. CDYL1c does not contain a chromodomain at all. Although CDYL1b displays binding affinity to methyl-lysine residues in different sequence context similar to chromodomains in other chromatin factors, we demonstrate that the CDYL1b chromodomain/H3K9me3 interaction is necessary but not sufficient for association of the factor with heterochromatin. Indeed, multimerization of the protein via the enoyl-CoA hydratase-like domain is essential for H3K9me3 chromatin binding in vitro and heterochromatin localization in vivo. In agreement, overexpression of CDYL1c that can multimerize, but does not interact with H3K9me3 can displace CDYL1b from heterochromatin. Our results imply that multimeric binding to H3K9me3 by CDYL1b homomeric complexes is essential for efficient chromatin targeting. We suggest that similar multivalent binding stably anchors other histone modification binding factors on their target chromatin regions.     

Postnatal developmental expression and localization of apelin and apelin receptor protein in the ovary and uterus of mice

Postnatal ovarian and uterine development is crucial to accomplished female fertility. Thus, the investigations of factors that present in pre-pubertal stages are important as it might be responsible for the regulation of ovarian and uterine function. Apelin, an adipokine and its receptor (APJ) are present in female reproductive organs. However, no study has reported its postnatal expression in uterus and ovary. Thus, we investigated the postnatal developmental changes in expression and localization of apelin and APJ in the ovary and uterus of mice. Postnatal ovary and uterus were collected from postnatal day (PND) 1, 7, 14, 21, 42, 65 and performed western blot analysis and immunohistochemistry. Uterine APJ is elevated in PND14 and PND65, whereas, ovarian APJ elevated in PND7, PND14, and PND65. Apelin expression in both ovary and uterus showed intense staining at PND65 and PND14. Our results showed that apelin and APJ abundance was lower at PND21 in uterus and ovary. In conclusion, apelin and APJ are developmentally regulated in the ovary and uterus, and its localization in the different compartments of ovary and uterus suggest its distribution specific physiological role in the uterus and ovary.     

Association between Circulating Levels of IGF-1 and IGFBP-3 and Lung Cancer Risk: A Meta-Analysis

Background

The insulin-like growth factor (IGF) system was documented to play a predominant role in neoplasia. As lung cancer is one of the most malignant cancers, we conducted a meta-analysis in order to investigate the strength of association between circulating IGF-1 and IGFBP-3 levels and lung cancer.

Methodology/Principal Findings

A systematic literature search was conducted to identify all prospective case-control studies and case-control studies on circulating IGFs and IGFBPs levels. Six nested case-control studies (1 043 case subjects and 11 472 control participants) and eight case-control studies (401 case subjects and 343 control participants) were included in this meta-analysis. Pooled measure was calculated as the inverse variance-weighted mean of the natural logarithm of multivariate adjusted OR with 95% CIs for highest vs. lowest levels to assess the association of circulating IGF-1 and IGFBP-3 concentrations and lung cancer. Standard mean difference (SMD) was also calculated to indicate the difference of the circulating IGF-1 and IGFBP-3 concentrations between the lung cancer case group and the control group. Of the nested case-control studies, ORs for the highest vs. lowest levels of IGF-1 and IGFBP-3 were 1.047 (95% CI: [0.802,1.367], P = 0.736) and 0.960 (95%CI: [0.591,1.559], P = 0.868) respectively; and SMDs were −0.079 (95%CI:[ −0.169, 0.011], P = 0.086) and −0.097 (95%CI:[ −0.264,0.071], P = 0.258) for IGF-1 and IGFBP-3 respectively. As to the case-control studies, SMDs were 0.568 (95%CI:[ −0.035, 1.171], P = 0.065) and −0.780 (95%CI:[ −1.358, −0.201], P = 0.008) for IGF-1 and IGFBP-3 respectively.

Conclusions/Significance

Inverse association was shown between IGFBP-3 and lung cancer in the case-control studies,and the circulating level of IGFBP-3 underwent a decline during tumorogenesis and development of lung cancer, which suggested IGFBP-3 a promising candidate for the biomarker of lung cancer.     

The histone demethylase Kdm3a is essential to progression through differentiation

Histone demethylation has important roles in regulating gene expression and forms part of the epigenetic memory system that regulates cell fate and identity by still poorly understood mechanisms. Here, we examined the role of histone demethylase Kdm3a during cell differentiation, showing that Kdm3a is essential for differentiation into parietal endoderm-like (PE) cells in the F9 mouse embryonal carcinoma model. We identified a number of target genes regulated by Kdm3a during endoderm differentiation; among the most dysregulated were the three developmental master regulators Dab2, Pdlim4 and FoxQ1. We show that dysregulation of the expression of these genes correlates with Kdm3a H3K9me2 demethylase activity. We further demonstrate that either Dab2 depletion or Kdm3a depletion prevents F9 cells from fully differentiating into PE cells, but that ectopic expression of Dab2 cannot compensate for Kdm3a knockdown; Dab2 is thus necessary, but insufficient on its own, to promote complete terminal differentiation. We conclude that Kdm3a plays a crucial role in progression through PE differentiation by regulating expression of a set of endoderm differentiation master genes. The emergence of Kdm3a as a key modulator of cell fate decision strengthens the view that histone demethylases are essential to cell differentiation.