Project description:The Nuclesome Remodelling and Deacetylation (NuRD) complex is an epigenetic regulator of gene expression comprising two mutually exclusive ATPase subunits CHD3 or CHD4. Here we show that CHD4 silencing in multiple types of cancer cells de-represses expression of the PADI1 (Protein Arginine Deiminase 1) and PADI3 enzymes that convert arginine to citrulline. Increased PADI1 and PADI3 expression enhances citrullination of three arginines of the key glycolytic regulatory enzyme PKM2 (pyruvate kinase) promoting excessive glycolysis, lowered ATP levels and slowed proliferation. PKM2 citrullination lowers its sensitivity to the allosteric inhibitors Tryptophan and Phenylalanine shifting equilibrium towards the allosteric activator Serine, thereby bypassing the normal physiological regulation of glycolysis by low Serine levels. Our results describe a novel pathway linking epigenetic regulation of PADI1 and PAD3 expression by CHD4 to glycolytic flux and the control of cancer cell growth.
Project description:The Nuclesome Remodelling and Deacetylation (NuRD) complex is an epigenetic regulator of gene expression comprising two mutually exclusive ATPase subunits CHD3 or CHD4. Here we show that CHD4 silencing in multiple types of cancer cells de-represses expression of the PADI1 (Protein Arginine Deiminase 1) and PADI3 enzymes that convert arginine to citrulline. Increased PADI1 and PADI3 expression enhances citrullination of three arginines of the key glycolytic regulatory enzyme PKM2 (pyruvate kinase) promoting excessive glycolysis, lowered ATP levels and slowed proliferation. PKM2 citrullination lowers its sensitivity to the allosteric inhibitors Tryptophan and Phenylalanine shifting equilibrium towards the allosteric activator Serine, thereby bypassing the normal physiological regulation of glycolysis by low Serine levels. Our results describe a novel pathway linking epigenetic regulation of PADI1 and PAD3 expression by CHD4 to glycolytic flux and the control of cancer cell growth.
Project description:Dynamic changes of histone epigenetic modifications and chromatin structure represent an universal mechanism by which cells adapt their transcriptional response to rapidly changing environmental conditions. During neuronal development, extensive chromatin remodeling takes place allowing the transition of pluripotent cells into differentiated neurons. Here we report that the ATP-dependent chromatin remodeling complex NuRD, which couples ATP-dependent nucleosome sliding with histone deacetylase activity, is a major remodeling complex in embryonic brain and plays an instructive role during mouse neuronal development. Importantly, the ATPase subunits of NuRD complex CHD3, CHD4 and CHD5 undergo a functional switch, thereby regulating distinct aspects of neuronal differentiation and migration in a sequential and mostly non-overlapping manner. We conclude that the recruitment of NuRD complexes containing specific CHDs to gene promoters and enhancers plays an instructive role in brain development. Gene expression analysis was performed in the mouse embryonic cortex at three developmental stages: E12.5, E15.5 and E18.5 using total RNA obtained from four embryos for each time point.
Project description:The NuRD complex is required for efficient and timely myelination in the peripheral nervous system. ChIP-chip assays were performed on rat sciatic nerve at P15, a peak timepoint of myelination, for binding of Chd4 to genes involved in regulating myelin formation. This experiment includes two custom ChIP-chip design incorporating many genes that are dynamically regulated during myelination. The antibodies used in this platform were Chd3/4 (Santa Cruz sc-11378) Chd4 (gift from Paul Wade), Mta2 (Santa Cruz sc-9447), and Nab2 (Santa Cruz sc-22815). Chd4 ChIP samples from experimental and input samples were hybridized.
Project description:ATP-dependent chromatin remodelers modulate gene expression by regulating genome accessibility and can contribute to tumorigenesis. In fusion-positive rhabdomyosarcoma (FP-RMS), we have previously identified the chromatin remodeler and NuRD subunit CHD4 as an essential gene for tumor survival. Here, we demonstrate that the FP-RMS vulnerability to CHD4 goes beyond its function as a NuRD member. Mechanistically, CHD4 interacts with BRD4 and co-localizes with the tumor driver and fusion protein PAX3-FOXO1 at super-enhancers where it generates a chromatin architecture permissive for the binding of the fusion protein. This allows the positioning of RNA polymerase 2 at promoters and the expression of the oncogenic program of PAX3-FOXO1. Additionally, analysis of genome-wide cancer dependency databases identifies CHD4 amongst the NuRD subunits as general novel cancer vulnerability. Our findings describe, for the first time, CHD4 as a regulator of super-enhancer-mediated gene expression and establish this chromatin remodeler as an unexpected broad tumor susceptibility.
Project description:Cardiac development relies on proper cardiomyocyte differentiation including expression and assembly of cell-type specific actomyosin subunits into a functional cardiac sarcomere. Control of this process involves not only promoting expression of cardiac sarcomere subunits but also repressing expression of non-cardiac myofibril paralogs. This level of transcriptional control requires broadly expressed multiprotein machines that modify and remodel the chromatin landscape to restrict transcription machinery access. Prominent among these is the Nucleosome Remodeling and Deacetylase (NuRD) complex, which includes the catalytic core subunit CHD4. Here, we demonstrate that direct CHD4-mediated repression of skeletal and smooth muscle myofibril isoforms is required for normal cardiac sarcomere formation, function, and embryonic survival early in gestation. Through transcriptomic and system genome-wide analyses of CHD4 localization, we identified novel CHD4 binding sites in smooth muscle myosin heavy chain, fast skeletal α-actin, and the fast skeletal troponin complex genes. We further demonstrate that in the absence of CHD4, cardiomyocytes in the developing heart form a hybrid muscle cell that contains cardiac, skeletal and smooth muscle myofibril components. These misexpressed paralogs intercalate into the nascent cardiac sarcomere to disrupt sarcomere formation and cause impaired cardiac function in utero. These results demonstrate the genomic and physiological requirements for CHD4 in mammalian cardiac development.
Project description:The combination of four proteins and their paralogues including MBD2/3, GATAD2A/B, CDK2AP1, and CHD3/4/5, which we refer to as the MGCC module, form the chromatin remodeling module of the Nucleosome Remodeling and Deacetylase (NuRD) complex. To date, mechanisms by which the MGCC module acquires paralogue-specific function and specificity have not been addressed. Understanding the protein-protein interaction (PPI) network of the MGCC subunits is essential in defining underlying mechanisms of gene regulation. Therefore, using pulldown followed by mass spectrometry analysis (PD-MS) we report a proteome-wide interaction network of the MGCC module in a paralogue-specific manner. Our data also demonstrate that the disordered C-terminal region of CHD3/4/5 is a gateway to incorporate remodeling activity into both the ChAHP (CHD4, ADNP, HP1γ) and NuRD complexes in a mutually exclusive manner. We define a short aggregation prone region (APR) within the C-terminal segment of GATAD2B that is essential for the interaction of CHD4 and CDK2AP1 with the NuRD complex. Finally, we also report an association of CDK2AP1 with the Nuclear Receptor Co-Repressor (NCOR) complex. Overall, this study provides insight into the possible mechanisms through which the MGCC module can achieve specificity and diverse biological functions.
Project description:Affinity purifications of CHD4 and CDK2AP2 to identify their interactors. The C-terminally tagged CHD4 has a C-terminal truncation to test whether this domain is required for the interaction with other NuRD subunits. GFP-purifications of both N- and C-terminally tagged CDK2AP2 were performed.