Epigenetic regulation of Atrophin1 by lysine-specific demethylase 1 is required for cortical progenitor maintenance
ABSTRACT: Lysine-specific demethylase 1 (LSD1) is involved in gene regulation and development; however, its precise function, molecular targets and underlying mechanisms during development are poorly understood. Here, we show that LSD1 is required for neuronal progenitor cell (NPC) maintenance during cortical development. A ChIP-seq analysis identified a LSD1 binding site (LBAL) downstream of Atrophin1 (ATN1). Surprisingly, tranylcypromine (LSD1 inhibitor) treatment increased H3K4 methylation at LBAL, leading to ATN1 repression and NPC differentiation. Knockdown of LSD1 and ATN1 phenocopied each other in inducing NPC premature differentiation and depletion which could be rescued by ATN1 overexpression, suggesting that LSD1 controls NPC differentiation via regulation of ATN1 methylation status and expression. The involvement of LSD1 in ATN1 expression and NPC maintenance were confirmed in knockout mice. These findings hint at the potential application for the clinical drug, tranylcypromine, in the prevention and/or treatment of ATN1-associated degenerative disease, dentatorubral-pallidoluysian atrophy. Examination of LSD1 binding sites in neuronal progenitor cells.
Project description:Here we describe that lysine-specific demethylase 1 (Lsd1/KDM1a), which demethylates histone H3 on Lys 4 or Lys 9 (H3K4/K9), is an indispensible epigenetic governor of hematopoietic differentiation. Integrative genomic analysis in primary hematopoietic cells, combining global occupancy of Lsd1, genome-wide analysis of its histone substrates H3K4 mono- and di-methylation and gene expression profiling, reveals that Lsd1 represses hematopoietic stem and progenitor cell (HSPC) gene expression programs during hematopoietic differentiation. We found that Lsd1 function was not restricted to transcription start sites, but is also critical at enhancers. Loss of Lsd1 at these sites was associated with increased H3K4me1 and H3K4me2 methylation levels on HSPC genes and their derepression. Failure to fully silence HSPC genes compromised differentiation of hematopoietic stem cells and mature blood cell lineages. Our data indicate that Lsd1-mediated concurrent repression of enhancer and promoter activity of stem and progenitor cell genes is a pivotal epigenetic mechanism required for proper hematopoietic maturation. To identify direct target genes of Lsd1 in myeloid cells we mapped global occupancy of Lsd1 in 32D granuolocytic progenitor cells and compared H3K4me1/me2/me3 and H3K27ac histone modifications in Lsd1fl/fl (wild type) vs. Lsd1fl/f Mx1Cre (knockout) Gr1dim Mac1 granuolocytic progenitor cells.
Project description:Cellular differentiation requires cells to undergo dramatic but strictly controlled changes in chromatin organization, transcriptional regulation, and protein production and interaction. To understand the regulatory connections between these processes, we applied a multi-omics approach integrating proteomic, transcriptomic, chromatin accessibility, protein occupancy, and protein-chromatin interaction data acquired during differentiation of mouse embryonic stem cells (ESCs) into post-mitotic neurons. We found extensive remodeling of the chromatin that was preceding changes on RNA and protein levels. We found the pluripotency factor Sox2 as regulator of neuron-specific genes and, as a potential mechanism, revealed its genomic redistribution from pluripotency enhancers to neuronal promoters and concomitant change of its protein interaction network upon differentiation. We identified Atrx as a major Sox2 partner in neurons, whose co-localisation correlated with an increase in active enhancer marks and increased expression of nearby genes, and where deletion of a Sox2-Atrx co-bound site resulted in reduced expression of the proximal gene. Collectively, these findings provide key insights into the regulatory transformation of Sox2 during neuronal differentiation and highlight the significance of multi-omic approaches in understanding gene regulation in complex systems.
Project description:Adipogenic differentiation and metabolic adaptation are initiated through transcriptional and epigenetic reprogramming. In particular, dynamic changes in histone modifications may play central roles in the rearrangement of gene expression patterns. LSD1 (KDM1) protein, encoded by aof2 gene, is a histone demethylase, which is involved in transcriptional regulation. Since the enzymatic activity of LSD1 is FAD (flavin adenine dinucleotide)-dependent, its effects on gene expression may be influenced by FAD availability. To address the importance of histone demethylation in adipogenic differentiation and function, we performed cDNA microarray in LSD1-deficient 3T3-L1 cells as well as in the cells treated with LSD1 inhibitor tranylcypromine (TC). FAD-synthesizing enyme, riboflavin kinase (RFK) -deficient cells were also subjected to the microarray analysis. Overall design: 3T3-L1 preadipocytes were transfected with aof2- or rfk- specific siRNA or control siRNA (siGL3) . 24 hours later, cells were subjected to adipogenic induction. 24 hours later, cells were harvested for total RNA extraction. For the TC treatment, TC was added to the adipogenic induction medium.
Project description:Analysis of differentiating C2C12 myoblasts treated with two LSD1 specific inhibitors. We found LSD1 is an important regulator of oxidative phenotypes in skeletal muscle cells. Results provide insight into the molecular mechanisms underlying roles of LSD1 in myocytes. Overall design: C2C12 cells were induced to differentiate with LSD1 inhibitors, tranylcypromine (TC) or S2101, or vehicle control. 48 hours later total RNAs were isolated and subjected with microarray analysis.
Project description:Adipogenic differentiation and metabolic adaptation are initiated through transcriptional and epigenetic reprogramming. In particular, dynamic changes in histone modifications may play central roles in the rearrangement of gene expression patterns. LSD1 (KDM1) protein, encoded by aof2 gene, is a histone demethylase, which is involved in transcriptional regulation. Since the enzymatic activity of LSD1 is FAD (flavin adenine dinucleotide)-dependent, its effects on gene expression may be influenced by FAD availability. To address the importance of histone demethylation in adipogenic differentiation and function, we performed cDNA microarray in LSD1-deficient 3T3-L1 cells as well as in the cells treated with LSD1 inhibitor tranylcypromine (TC). FAD-synthesizing enyme, riboflavin kinase (RFK) -deficient cells were also subjected to the microarray analysis. 3T3-L1 preadipocytes were transfected with aof2- or rfk- specific siRNA or control siRNA (siGL3) . 24 hours later, cells were subjected to adipogenic induction. 24 hours later, cells were harvested for total RNA extraction. For the TC treatment, TC was added to the adipogenic induction medium.
Project description:Transcription factors and chromatin modifiers play important roles in programming and reprogramming of cellular states during development. Much is known about the role of these regulators in gene activation, but relatively little is known about the critical process of enhancer silencing during differentiation. Here we show that the H3K4/K9 histone demethylase LSD1 plays an essential role in decommissioning enhancers during differentiation of embryonic stem cells (ESCs). LSD1 occupies enhancers of active genes critical for control of ESC state. However, LSD1 is not essential for maintenance of ESC identity. Instead, ESCs lacking LSD1 activity fail to fully differentiate and ESC-specific enhancers fail to undergo the histone demethylation events associated with differentiation. At enhancers, LSD1 is a component of the NuRD complex, which contains additional subunits that are necessary for ESC differentiation. We propose that the LSD1-NuRD complex decommissions enhancers of the pluripotency program upon differentiation, which is essential for complete shutdown of the ESC gene expression program and the transition to new cell states. This is the ChIP-seq part of the study.
Project description:Using a mouse model of human MLL-AF9 leukemia, we identified the lysine-specific demethylase KDM1A (LSD1 or AOF2) as an essential regulator of leukemia stem cell (LSC) potential. KDM1A acts at genomic loci bound by MLL-AF9 to sustain expression of the associated oncogenic program, thus preventing differentiation and apoptosis. In vitro and in vivo pharmacologic targeting of KDM1A using tranylcypromine analogues active in the nanomolar range phenocopied Kdm1a knockdown in both murine and primary human AML cells exhibiting MLL translocations. By contrast, the clonogenic and repopulating potential of normal hematopoietic stem and progenitor cells was spared. Our data establish KDM1A as a key effector of the differentiation block in MLL leukemia which may be selectively targeted to therapeutic effect. To investigate the effects of Kdm1a KD on histone modifications, we performed chromatin immunoprecipitation followed by next-generation sequencing (ChIP-Seq) in control and Kdm1a KD MLL-AF9 AML cells for dimethyl-H3K4 and dimethyl-H3K9, as well as for trimethyl-H3K4 and trimethyl-H3K9. Dimethyl-H3K4 and dimethyl-H3K9 are targeted for demethylation by KDM1A. For each of these histone modifications, we compared the mean ChIP-Seq signal across and around protein coding genes bound by the MLL-AF9 oncoprotein (Bernt et al., 2011) with the mean signal from genes not bound by MLL-AF9 expressed at high, middle or low levels.
Project description:Loss of Lsd1 in Drosophila in specific cells of the Drosophila ovary results in increased BMP signaling outside the cap cell niche and an expanded germline stem cell (GSC) phenotype. To better characterize the function of Lsd1 in different cell populations within the ovary, we performed Chromatin immunoprecipitation coupled with massive parallel sequencing (ChIP-seq). This analysis shows that Lsd1 associates with a surprisingly limited number of sites in escort cells and fewer, and often, different sites in cap cells. These findings indicate that Lsd1 displays highly selective binding in specific cellular contexts. Examination of epitope tagged Lsd1 transgenes in specific cell populations within the Drosophila ovary
Project description:We report the identification of LSD1 binding genomic regions in mouse embryonic stem cells (ESC) by high throughput sequencing. By obtaining over 10 million 36 bp reads of sequence from each chromatin immunoprecipitated DNA, we generated genome-wide maps for LSD1 and histone H3 dimethylated on lysine 4 (H3K4me2), the substrate for LSD1 in mouse ESCs. Our results showed an extensive overlap between the LSD1 and H3K4me2 genomic regions and a correlation between the genomic levels of LSD1/H3K4me2 and gene expression, including many highly expressed ESC genes. LSD1 is recruited to the chromatin of cells in the G1/S/G2 phases and is displaced from the chromatin of M phase cells, suggesting that LSD1 or H3K4me2 alternatively occupies LSD1 genomic regions during cell cycle progression. LSD1 knockdown by RNA interference or its displacement from the chromatin by anti-neoplastic agents caused an increase in the levels of a subset of LSD1 target genes. Taken together, these results suggest that cell-cycle dependent association and dissociation of LSD1 with chromatin mediates short-time scale gene expression changes during ES cell cycle progression. Examination of LSD1 and lysine 4 dimethylated histone H3 (H3K4me2) binding genomic regions in embryonic stem cells. Input genomic DNA and DNA immunoprecipitaed with control IgG was included as controls.
Project description:we explored the changes in metabolic gene expression during neuronal differentiation from neural progenitor cells (NPC). Overall design: Examination of transcription profile in NPC and neurons.