Project description:Genetic mutations in pancreatic ductal adenocarcinoma (PDAC) with critical roles have been well examined. The recent discovery of alterations in genes encoding histone modifiers suggests their possible roles in the complexity of cancer development. We previously reported loss of heterozygosity of the KDM6B gene, which encodes a histone demethylase for trimethylated histone H3 lysine 27 (H3K27me3), a repressive chromatin mark, in PDAC cells. In this study, we demonstrated that loss of KDM6B enhanced aggressiveness of PDAC cells. KDM6B has been regarded as a tumor suppressor that mediates oncogenic KRAS-induced senescence. Consistently, KDM6B was highly expressed in pancreatic precancerous lesions (pancreatic intraepithelial neoplasms); then, the expression decreased as the malignant grade progressed. We found that knockdown of KDM6B in PDAC cells promoted tumor sphere formation and increased peritoneal dissemination and liver metastasis in vivo. Microarray and chromatin immunoprecipitation analysis implicated CEBPA for aggressiveness induced by KDM6B knockdown. CEBPA knockdown recapitulated the phenotypic change of PDAC cells after KDM6B knockdown, which was reversed by forced expression of C/EBPα. Moreover, similar protein expression patterns of KDM6B and C/EBPα in human PDAC emphasized their functional correlation. Notably, pharmacological inhibition of the H3K27 methylase EZH2 in PDAC cells inhibited tumor sphere formation along with the upregulation of CEBPA expression, and this effect was impaired in KDM6B knockdown cells, highlighting the role for KDM6B in the activation of CEBPA. Together, our results propose a significant role for the KDM6B-C/EBPα axis in the PDAC phenotype.
Project description:Background& Aims: The incidence of nonhepatitis B and nonhepatitis C viral (NBNC)- HCC has been rising in recent years due to the increase in NAFLD and NASH worldwide with fibrosis. However, the molecular mechanisms underlying the progression of these HCC are not fully understood. Here we observed that KDM6B, an H3K27 demethylase, was commonly downregulated in human NBNC-HCC and mouse NASH-related HCC by microarray analysis. The study aims to elucidate the molecular mechanism of KDM6B downregulation in NBNC-HCC including NASH-related HCC. Approach & Results: By immunohistochemistry, KDM6B expression was decreased in 28.7% of human HCC tissues, most of which were NBNC-HCC type. The low KDM6B expression group was accompanied by NASH in the adjacent liver. The KDM6B knockout (KO) HCC cells altered pathways of lipid metabolism by microarray and GSEA analysis. The KDM6B-KO cells significantly decreased lipid accumulation and cell reduction rates. Expression of two lipid-metabolism-related genes, G0S2 and ACSL1, were suppressed in the KDM6B-KO cells and the histone H3K27 trimethylation levels at the promoter regions were decreased when compared to the wild-type cells. Knockdown of G0S2 but not ACSL1 expression showed resistance to lipotoxicity in HCC cells. Moreover, inhibition of ATGL, a downstream target of G0S2, caused a decrease in lipid accumulation and cell proliferation. Conclusions: KDM6B regulates G0S2 expression via histone demethylation of its promoter region. Decreased KDM6B-dependent G0S2 expression through the histone modification pathway causes resistance to lipotoxicity, which may be involved in the carcinogenic mechanism of NASH-related HCC among NBNC-HCC.
Project description:Glioblastoma (GBM) tumors are enriched in immune-suppressive myeloid cells and are refractory to immune checkpoint therapy (ICT). Targeting epigenetic pathways to reprogram the functional phenotype of immune-suppressive myeloid cells to overcome resistance to ICT remains unexplored. Single-cell and spatial transcriptomic analyses of human GBM tumors demonstrated high expression of an epigenetic enzyme - histone 3 lysine 27 demethylase (KDM6B) in intra-tumoral immune-suppressive myeloid cell subsets. Importantly, myeloid-cell specific Kdm6b deletion enhanced pro-inflammatory pathways and improved survival in GBM tumor-bearing mice. Mechanistic studies elucidated that the absence of Kdm6b enhances antigen-presentation, interferon response and phagocytosis in myeloid cells by inhibiting mediators of immune suppression including Mafb, Socs3 and Sirpa. Further, pharmacological inhibition of KDM6B mirrored the functional phenotype of Kdm6b deleted myeloid cells and enhanced anti-PD1 efficacy. Thus, this study identified KDM6B as an epigenetic regulator of the functional phenotype of myeloid cell subsets and a potential therapeutic target to improve response to ICT.
Project description:Recent studies have indicated that the histone 3 lysine 27 (H3K27me2/3) demethylase KDM6B (JMJD3) is frequently upregulated in a myriad of blood disorders including myelodysplastic syndrome (MDS), T-cell acute lymphoblastic leukemia (T-ALL), and multiple myeloma (MM) suggesting it may have important functions in the pathogenesis of hematopoietic cancers. Here, we sought to determine the role of Kdm6b in hematopoietic stem cell (HSC) fate decisions under normal and malignant conditions to evaluate its potential as a therapeutic target. We show that loss of Kdm6b leads to a significant reduction in phenotypic and functional HSCs in adult mice, and that Kdm6b is necessary for HSC self-renewal in response to inflammatory, genotoxic and oncogenic stress. Additionally, we show that loss of Kdm6b in HSCs leads to a stress-response gene expression signature in native HSCs that is independent of its demethylase activity. Loss of Kdm6b lead to increased expression of a subset of genes implicated in HSC quiescence (e.g. Fos, Jun, Ier2, Dusp1, Zfp36). Upon inflammatory or replicative stress, HSCs deficient for Kdm6b are not able to efficiently resolve this gene expression program, leading to increased quiescence and a self-renewal block, forcing them to differentiate. These findings show that Kdm6b is necessary for self-renewal of normal and leukemic stem cells, and suggest inhibiting Kdm6b in blood cancers in the presence of proliferative agents may force differentiation and eventual depletion of leukemic stem cells.
Project description:Recent studies have delineated cancer type-specific roles of histone 3 lysine 27 (H3K27) demethylase KDM6B/JMJD3 depending on its H3K27 demethylase activity. Here we show that KDM6B is expressed in multiple myeloma (MM); and that shRNA-mediated knockdown and CRISPR-mediated knockout of KDM6B abrogate MM cell growth and survival. TNFα or bone marrow stromal cell culture supernatants induce KDM6B, which is blocked by IKKβ inhibitor MLN120B, suggesting KDM6B is regulated by NF-κB signaling in MM cells. RNA-sequencing and subsequent ChIP-qPCR analyses reveal that KDM6B is recruited to the loci of genes encoding components of MAPK signaling pathway including ELK1 and FOS, and upregulates these genes expression without affecting H3K27 methylation level. Overexpression of catalytically-inactive KDM6B activates expression of MAPK pathway-related genes, confirming its function independent of demethylase activity. We further demonstrate that downstream targets of KDM6B, ELK1 and FOS, confer MM cell growth. Our study therefore delineates KDM6B function that links NF-κB and MAPK signaling pathway mediating MM cell growth and survival, and validates KDM6B as a novel therapeutic target in MM.
Project description:The KDM6 histone demethylases (UTX/KDM6A and JMJD3/KDM6B) mediate removal of repressive histone H3K27me3 marks to establish transcriptionally permissive chromatin. Loss of UTX in female mice is embryonic lethal. Unexpectedly, male UTX-null mice escape embryonic lethality due to expression of UTY, a paralog lacking H3K27-demethylase activity. This suggests that UTX plays an enzyme-independent role in development, and challenges the need for active H3K27-demethylation in vivo. However, the requirement for active H3K27-demethylation in stem cell-mediated tissue regeneration remains untested. Using an inducible mouse knockout that ablates UTX in satellite cells, we show that active H3K27-demethylation is necessary for muscle regeneration. Indeed, loss of UTX in satellite cells blocks myofiber regeneration in both male and female mice. Furthermore, we demonstrate that UTX mediates muscle regeneration through its H3K27-demethylase activity using a chemical inhibitor, and a demethylase-dead UTX knock-in mouse. Mechanistically, dissection of the muscle regenerative process revealed that UTX is required for expression of the transcription factor Myogenin that drives differentiation of muscle progenitors. Thus, we have identified a critical role for the enzymatic activity of UTX in activating muscle-specific gene expression during myofiber regeneration, revealing for the first time that active H3K27-demethylation has a physiological role in vivo. Satellite cells were sorted based on Cre-dependent expression of TdT reporter gene. Sorted UTXmKO or UTX WT satellite cells were then induced to differentiate for 24 hrs. RNA was then isolated and subjected to RNA-Seq analysis.
Project description:C/EBPα is a potent inducer of lymphoid to myeloid cell transdifferentiation. Here we describe that Carm1 methylates arginine 35 in the transactivation domain of C/EBPα, modulating the factor’s activity. Inhibition of methylation or mutation of R35 dramatically enhances the capacity of C/EBPα to induce a B cell-to-macrophage conversion through accelerated chromatin remodeling and subsequent upregulation of myeloid genes and downregulation of B cell genes. This phenomenon is mediated by an increased interaction of unmethylated C/EBPα with the bi-lineage transcription factor PU.1, resulting in the accelerated relocation of PU.1 from B cell to myeloid gene regulatory elements and thus enhancing chromatin remodeling. Our data suggests that C/EBPα effectively converts PU.1 from a B cell to a myeloid regulator through a ‘stealing’ process, and that methylation of C/EBPα by Carm1 modulates this interaction. We propose that individual cells display a pool of methylated and unmethylated C/EBPα, and the proportion of the two molecular forms determines the velocity of cell fate conversion.
Project description:C/EBPα is a potent inducer of lymphoid to myeloid cell transdifferentiation. Here we describe that Carm1 methylates arginine 35 in the transactivation domain of C/EBPα, modulating the factor’s activity. Inhibition of methylation or mutation of R35 dramatically enhances the capacity of C/EBPα to induce a B cell-to-macrophage conversion through accelerated chromatin remodeling and subsequent upregulation of myeloid genes and downregulation of B cell genes. This phenomenon is mediated by an increased interaction of unmethylated C/EBPα with the bi-lineage transcription factor PU.1, resulting in the accelerated relocation of PU.1 from B cell to myeloid gene regulatory elements and thus enhancing chromatin remodeling. Our data suggests that C/EBPα effectively converts PU.1 from a B cell to a myeloid regulator through a ‘stealing’ process, and that methylation of C/EBPα by Carm1 modulates this interaction. We propose that individual cells display a pool of methylated and unmethylated C/EBPα, and the proportion of the two molecular forms determines the velocity of cell fate conversion.
Project description:C/EBPα is a potent inducer of lymphoid to myeloid cell transdifferentiation. Here we describe that Carm1 methylates arginine 35 in the transactivation domain of C/EBPα, modulating the factor’s activity. Inhibition of methylation or mutation of R35 dramatically enhances the capacity of C/EBPα to induce a B cell-to-macrophage conversion through accelerated chromatin remodeling and subsequent upregulation of myeloid genes and downregulation of B cell genes. This phenomenon is mediated by an increased interaction of unmethylated C/EBPα with the bi-lineage transcription factor PU.1, resulting in the accelerated relocation of PU.1 from B cell to myeloid gene regulatory elements and thus enhancing chromatin remodeling. Our data suggests that C/EBPα effectively converts PU.1 from a B cell to a myeloid regulator through a ‘stealing’ process, and that methylation of C/EBPα by Carm1 modulates this interaction. We propose that individual cells display a pool of methylated and unmethylated C/EBPα, and the proportion of the two molecular forms determines the velocity of cell fate conversion.
Project description:The discovery of the first histone demethylase in 2004 (LSD1/KDM1) opened new avenues for the understanding of how histone methylation impacts cellular functions. A great number of histone demethylases have been identified since, which are potentially linked to gene regulation as well as to stem cell self-renewal and differentiation. KDM6A/UTY and KDM6B/JMJD3 are both H3K27me3/2-specific histone demethylases, which are known to play a central role in regulation of posterior development, by regulating HOX gene expression. So far nothing is known about the role of histone lysine demethylases (KDMs) during early hematopoiesis. We are studying the role of KDM6A and KDM6B on self-renewal, global gene expression and on local and global chromatin states in embryonic stem cells (ESCs) and during differentiation. In order to completely abrogate KDM6 demethylase activity in ESCs we employed a specific inhibitor (GSK-J4, Kruidenier et al. 2012). Treatment of ESCs with GSK-J4 had no effect on viability and proliferation . However, ESC differentiation in the presence of GSK-J4 was completely abrogated. In conclusion we show that ESC differentiation is completely blockend in the absence of any H3K27 demethylase activity. We used microarrays to detail the global gene expression program of genes which are differentially expressed during the early differentiation of ESC derived embryoid bodies (EBs) in the presence of GSK-J4 (KDM6 Inhibitor). ESCs (R1) have been cultured and differentiated in the presence of GSK-J4 a KDM6 specific inhibitor.