Project description:Promoter-specific recruitment of PPARG in adipocytes depends on GPS2-dependent stabilization of histone demethylase KDM4A/JMJD2 [GPS2]
Project description:Promoter-specific recruitment of PPARG in adipocytes depends on GPS2-dependent stabilization of histone demethylase KDM4A/JMJD2 [KDM4A]
Project description:Timely and selective recruitment of transcription factors to their appropriate DNA-binding sites represents a critical step in regulating gene activation; however the regulatory strategies underlying each factor’s effective recruitment to specific promoter and/or enhancer regions are not fully understood. Here, we identify an unexpected regulatory mechanism by which promoter-specific binding, and therefore function, of PPARG in adipocytes requires G protein Suppressor 2 (GPS2) to prime the local chromatin environment via inhibition of the ubiquitin ligase RNF8 and stabilization of the H3K9 histone demethylase KDM4A/JMJD2. Integration of genome-wide profiling data indicates that the pioneering activity of GPS2/KDM4A is required for PPARG mediated regulation of a specific transcriptional program, including the lipolytic enzymes ATGL and HSL. Hence, our findings reveal that GPS2 exerts a biologically important function in adipose tissue lipid mobilization by directly regulating ubiquitin signaling and indirectly modulating chromatin remodeling to prime selected genes for activation.
Project description:Timely and selective recruitment of transcription factors to their appropriate DNA-binding sites represents a critical step in regulating gene activation; however the regulatory strategies underlying each factor’s effective recruitment to specific promoter and/or enhancer regions are not fully understood. Here, we identify an unexpected regulatory mechanism by which promoter-specific binding, and therefore function, of PPARG in adipocytes requires G protein Suppressor 2 (GPS2) to prime the local chromatin environment via inhibition of the ubiquitin ligase RNF8 and stabilization of the H3K9 histone demethylase KDM4A/JMJD2. Integration of genome-wide profiling data indicates that the pioneering activity of GPS2/KDM4A is required for PPARG mediated regulation of a specific transcriptional program, including the lipolytic enzymes ATGL and HSL. Hence, our findings reveal that GPS2 exerts a biologically important function in adipose tissue lipid mobilization by directly regulating ubiquitin signaling and indirectly modulating chromatin remodeling to prime selected genes for activation.
Project description:Here we demonstrate that the loss of GPS2 triggers the reprogramming of cellular processes related to adipocyte differentiation by increasing the responses to the adipogenic cocktail. Moreover, GPS2-depleted human adipocytes are characterized by hypertrophy, triglyceride and phospholipid accumulation, and sphingomyelin depletion. These changes are likely a consequence of the increased expression of ATP-Binding cassette subfamily G member 1 (ABCG1) that mediates sphingomyelin efflux from adipocytes and modulates lipoprotein lipase (LPL) activity. We identify ABCG1 as a direct transcriptional target, as GPS2 depletion leads to coordinated changes of transcription and H3K27 acetylation at promoter and enhancers which are occupied by GPS2 in wild-type adipocytes. Finally, we find that in omental adipose tissue of obese humans GPS2 levels correlate with ABCG1 levels, type 2 diabetic status, and lipid metabolic status.
Project description:We have characterized the role of the Jmjd2/Kdm4 proteins in embryonic stem cell (ESC) biology, histone methylation and gene regulation. The Jmjd2 proteins are H3K9/H3K36 histone demethylases and three Jmjd2 family members are expressed in ESCs: Jmjd2a/Kdm4a, Jmjd2b/Kdm4b and Jmjd2c/Kdm4c/Gasc1. We find that specifically Jmjd2a and Jmjd2c exert redundant functions, which are essential for ESC self-renewal and early embryonic development. ChIP-seq studies show that Jmjd2a and Jmjd2c both localize to H3K4me3 marked regions, where they have general and widespread roles preventing the accumulation of especially H3K9me3, but also H3K36me3. Jmjd2 catalytic activity is required for ESC maintenance, and increased H3K9me3 levels in knockout ESCs compromise the expression of several Jmjd2a/c targets, including genes that are important for ESC self-renewal. Thus, continual removal of H3K9 promoter methylation by Jmjd2 demethylases represents a novel mechanism ensuring transcriptional competence and stability of the pluripotent cell identity.
Project description:We have characterized the role of the Jmjd2/Kdm4 proteins in embryonic stem cell (ESC) biology, histone methylation and gene regulation. The Jmjd2 proteins are H3K9/H3K36 histone demethylases and three Jmjd2 family members are expressed in ESCs: Jmjd2a/Kdm4a, Jmjd2b/Kdm4b and Jmjd2c/Kdm4c/Gasc1. We find that specifically Jmjd2a and Jmjd2c exert redundant functions, which are essential for ESC self-renewal and early embryonic development. ChIP-seq studies show that Jmjd2a and Jmjd2c both localize to H3K4me3 marked regions, where they have general and widespread roles preventing the accumulation of especially H3K9me3, but also H3K36me3. Jmjd2 catalytic activity is required for ESC maintenance, and increased H3K9me3 levels in knockout ESCs compromise the expression of several Jmjd2a/c targets, including genes that are important for ESC self-renewal. Thus, continual removal of H3K9 promoter methylation by Jmjd2 demethylases represents a novel mechanism ensuring transcriptional competence and stability of the pluripotent cell identity.
Project description:To establish a robust cellular model system for screening genes associated with cell invasion, we over-expressed the oncogenic translocated promoter region (Tpr)-MET proteins in SCC23 cells (SCC23/MET). Using a functional siRNA screen, we identified that the histone demethylase KDM4A played a critical role in the invasive growth and metastasis of SCC mediated by the Oncogenic MET. To investigate the molecular mechanism through which KDM4A inhibit the tumor cell invasion, we knock-down KDM4A in SCC23/MET cell and performed a gene microarray to examine which genes may be regulaged by kDM4A. We generated two stable cell lines. one was infected with virus containing scramble and another infected with virus infected with virus containing KDM4A shRNA. Total RNA were extracted from these two cell lines and subject to microarray.
Project description:To establish a robust cellular model system for screening genes associated with cell invasion, we over-expressed the oncogenic translocated promoter region (Tpr)-MET proteins in SCC23 cells (SCC23/MET). Using a functional siRNA screen, we identified that the histone demethylase KDM4A played a critical role in the invasive growth and metastasis of SCC mediated by the Oncogenic MET. To investigate the molecular mechanism through which KDM4A inhibit the tumor cell invasion, we knock-down KDM4A in SCC23/MET cell and performed a gene microarray to examine which genes may be regulaged by kDM4A.
Project description:As most of the mitochondrial proteome is encoded in the nucleus, mitochondrial functions critically depend on nuclear gene expression and bidirectional mito-nuclear communication. However, mitochondria-to-nucleus communication pathways are incompletely understood. Here, we identify G-Protein Pathway Suppressor 2 (GPS2) as a mediator of mitochondrial retrograde signaling and a key transcriptional activator of nuclear-encoded mitochondrial genes in mammals. GPS2 regulated translocation from mitochondria to nucleus is essential for the transcriptional activation of the nuclear stress response to mitochondrial depolarization and for supporting basal mitochondrial biogenesis in differentiating adipocytes and in brown adipose tissue from mice. In the nucleus, GPS2 recruitment to target gene promoters regulates histone H3K9 demethylation and RNA Polymerase II (POL2) activation through inhibition of Ubc13-mediated ubiquitination. These findings, together, reveal an unexpected layer of regulation of mitochondrial gene transcription, uncover a novel direct mitochondria-nuclear communication pathway and indicate that GPS2 retrograde signaling is a key component of the mitochondrial stress response in mammals.