Effect of Sumo2 deletion on gene expression in the mouse brain
Ontology highlight
ABSTRACT: Mounting evidence indicates that small ubiquitin-like modifier (SUMO) conjugation regulates a wide range of neuronal functions and participates in learning and memory processes. Since many SUMO targets are transcription factors as well as other nuclear proteins modulating gene expression and SUMO2 is the predominant SUMO isoform, we aimed to identify how SUMO2 regualtes gene expression in the brain in order to better understand the role of SUMOylation in the brain fucntcion. In this study, we peformed RNA-Seq anaysis on hippocampus from SUMO2 conditional knockout mice.
Project description:Heat shock induces rapid modification of proteins with SUMO2/3. This study concentrated in charaterizing how these changes are reflected on SUMOylation of chromatin bound proteins, trancsription, and chromatin binding of SUMO ligase PIAS1. Comparison of chromatin SUMO2/3 modification pattern in non-stressed and heat shocked K562 and VCaP cells. All samples were done as biological replicates. In K562 cells, SUMO2/3 ChIP-seq was done in non-stressed (37C) and heat shocked (30min at 43C) cells. The effect of heat shock factor 1 (HSF1) to chromatin SUMOylation in HS was studied in HSF1 silenced (shHSF1) K562 cells (non-stressed vs. heat shocked) using scramble shRNA transfected cells as control (shSCR). SUMO2/3, SUMO ligase PIAS1,and RNA polymerase II binding in HS (30 min at 43C) and recovery from HS (1h at 37C after HS) was studied using ChIP-seq. Effect of PIAS1 for chromatin SUMOylation was studied in PIAS1 silenced (siRNA for PIAS1, siPIAS1) cells (non-stressed or heat shocked) using non-targeting siRNA transfected cells as a control (siNON). Effect of SUMOylation to chromatin binding of RNA polymerase II was studied in UBE2I silenced (siRNA for UBE2I) and control (non-targeting siRNA transfected, siNON) VCaP cells (non-stressed or heat shocked). Effect of transtription inhibition for chromatin SUMOylation was studied in TRP (triptolide; 1 micromolar, 3h) and DRB (5,6-Dichlorobenzimidazole 1-beta-D-ribofuranosidase; 100 micromolar, 3h) treated VCaP cells. GRO-seq was used to determine HS-induced changes in nascent transcription in K562 cells.
Project description:Heat shock induces rapid modification of proteins with SUMO2/3. This study concentrated in charaterizing how these changes are reflected on SUMOylation of chromatin bound proteins, trancsription, and chromatin binding of SUMO ligase PIAS1.
Project description:The chromatin organizers Satb1 and Satb2 regulate developmental genes in a tissue- and locus-specific manner. In mouse Embryonic Stem Cells (mESCs), the Satb proteins are involved in the balance between pluripotency and differentiation by direct control of key developmental factors such as Nanog and a number of Hox genes. Despite their structural similarities, the Satb proteins regulate mESC pluripotency in opposing ways: Satb1 promotes differentiation by repressing Nanog and activating the neural genes Bcl2 and Nestin, while Satb2 supports the pluripotent state by activating Nanog and repressing Satb1. To further address the mechanisms by which the Satb proteins regulate gene expression, we examined the conjugation of Satb2 with the small ubiquitin-like modifier (SUMO) in pluripotent and differentiated mESCs. We describe for the first time the endogenous SUMOylation of Satb2 in mESCs as a response to developmental cues. We found that Satb2 is progressively SUMO2-modified during differentiation of ESCs towards ectodermal precursors. Moreover, we identified Zfp451 as a SUMO E3 ligase able to interact with and modify Satb2 with SUMO2 in vitro and in vivo. Ablation of Zfp451 or mutation of the SUMO-acceptor lysines in the Satb2 protein disrupt the ability of mESCs to efficiently shut-down pluripotency genes and activate the differentiation program. Importantly, forced expression of SUMO2-Satb2 N-terminal fusions rescues the differentiation defect of SUMO-Satb2 deficient mESCs. Mechanistically, SUMOylation reduces binding of Satb2 to a subset of loci associated to pluripotency genes and changes the composition of Satb2-containing complexes in chromatin. Taken together, our data suggests that SUMO modification of the chromatin organizer Satb2 by the E3 ligase Zfp451 is required for the efficient downregulation of pluripotency genes and initiation of the differentiation program in mouse embryonic stem cells.
Project description:The chromatin organizers Satb1 and Satb2 regulate developmental genes in a tissue- and locus-specific manner. In mouse Embryonic Stem Cells (mESCs), the Satb proteins are involved in the balance between pluripotency and differentiation by direct control of key developmental factors such as Nanog and a number of Hox genes. Despite their structural similarities, the Satb proteins regulate mESC pluripotency in opposing ways: Satb1 promotes differentiation by repressing Nanog and activating the neural genes Bcl2 and Nestin, while Satb2 supports the pluripotent state by activating Nanog and repressing Satb1. To further address the mechanisms by which the Satb proteins regulate gene expression, we examined the conjugation of Satb2 with the small ubiquitin-like modifier (SUMO) in pluripotent and differentiated mESCs. We describe for the first time the endogenous SUMOylation of Satb2 in mESCs as a response to developmental cues. We found that Satb2 is progressively SUMO2-modified during differentiation of ESCs towards ectodermal precursors. Moreover, we identified Zfp451 as a SUMO E3 ligase able to interact with and modify Satb2 with SUMO2 in vitro and in vivo. Ablation of Zfp451 or mutation of the SUMO-acceptor lysines in the Satb2 protein disrupt the ability of mESCs to efficiently shut-down pluripotency genes and activate the differentiation program. Importantly, forced expression of SUMO2-Satb2 N-terminal fusions rescues the differentiation defect of SUMO-Satb2 deficient mESCs. Mechanistically, SUMOylation reduces binding of Satb2 to a subset of loci associated to pluripotency genes and changes the composition of Satb2-containing complexes in chromatin. Taken together, our data suggests that SUMO modification of the chromatin organizer Satb2 by the E3 ligase Zfp451 is required for the efficient downregulation of pluripotency genes and initiation of the differentiation program in mouse embryonic stem cells.
Project description:The chromatin organizers Satb1 and Satb2 regulate developmental genes in a tissue- and locus-specific manner. In mouse Embryonic Stem Cells (mESCs), the Satb proteins are involved in the balance between pluripotency and differentiation by direct control of key developmental factors such as Nanog and a number of Hox genes. Despite their structural similarities, the Satb proteins regulate mESC pluripotency in opposing ways: Satb1 promotes differentiation by repressing Nanog and activating the neural genes Bcl2 and Nestin, while Satb2 supports the pluripotent state by activating Nanog and repressing Satb1. To further address the mechanisms by which the Satb proteins regulate gene expression, we examined the conjugation of Satb2 with the small ubiquitin-like modifier (SUMO) in pluripotent and differentiated mESCs. We describe for the first time the endogenous SUMOylation of Satb2 in mESCs as a response to developmental cues. We found that Satb2 is progressively SUMO2-modified during differentiation of ESCs towards ectodermal precursors. Moreover, we identified Zfp451 as a SUMO E3 ligase able to interact with and modify Satb2 with SUMO2 in vitro and in vivo. Ablation of Zfp451 or mutation of the SUMO-acceptor lysines in the Satb2 protein disrupt the ability of mESCs to efficiently shut-down pluripotency genes and activate the differentiation program. Importantly, forced expression of SUMO2-Satb2 N-terminal fusions rescues the differentiation defect of SUMO-Satb2 deficient mESCs. Mechanistically, SUMOylation reduces binding of Satb2 to a subset of loci associated to pluripotency genes and changes the composition of Satb2-containing complexes in chromatin. Taken together, our data suggests that SUMO modification of the chromatin organizer Satb2 by the E3 ligase Zfp451 is required for the efficient downregulation of pluripotency genes and initiation of the differentiation program in mouse embryonic stem cells.
Project description:SUMOylation is a form of post-translational modification involving covalent attachment of SUMO (Small Ubiquitin-like Modifier) polypeptides to specific lysine residues in the target protein. In human cells, there are four SUMO proteins, SUMO1–4, with SUMO2 and SUMO3 forming a closely related subfamily. SUMO2/3, in contrast to SUMO1, are predominantly involved in the cellular response to certain stresses, including heat shock. Substantial evidence from studies in yeast has shown that SUMOylation plays an important role in the regulation of DNA replication and repair. Here, we report a proteomic analysis of proteins modified by SUMO2 in response to DNA replication stress in S phase in human cells. We have identified a panel of 22 SUMO2 targets with increased SUMOylation during DNA replication stress, many of which play key functions within the DNA replication machinery and/or in the cellular response to DNA damage. Interestingly, POLD3 was found modified most significantly in response to a low dose aphidicolin treatment protocol that promotes common fragile site (CFS) breakage. POLD3 is the human ortholog of POL32 in budding yeast, and has been shown to act during break-induced recombinational repair. We have also shown that deficiency of POLD3 leads to an increase in RPA-bound ssDNA when cells are under replication stress, suggesting that POLD3 plays a role in the cellular response to DNA replication stress. Considering that DNA replication stress is a source of genome instability, and that excessive replication stress is a hallmark of pre-neoplastic and tumor cells, our characterization of SUMO2 targets during a perturbed S-phase should provide a valuable resource for future functional studies in the fields of DNA metabolism and cancer biology.
Project description:The generation of induced pluripotent stem cells (iPSCs) from differentiated cells following forced expression of Oct4, Klf4, Sox2 and c-Myc (OKSM) is slow and inefficient, suggesting that transcription factors have to overcome somatic barriers that resist cell fate change. Here, we performed an ubiased serial shRNA enrichment screen to identify novel repressors of somatic cell reprogramming into iPSCs. This effort uncovered the sumoylation effector protein Sumo2 as one of the strongest roadblocks to iPSC formation. Depletion of Sumo2 both enhances and accelerates reprogramming, yielding transgene-independent, chimera-competent iPSCs after as little as 36 hours of OKSM expression. We further show that the Sumo2 pathway acts independently of exogenous c-Myc expression and in parallel with small molecule enhancers of reprogramming. Critically, suppression of SUMO2 also promotes the generation of human iPSCs. Together, our results reveal sumoylation as a crucial post-transcriptional mechanism that resists the acquisition of pluripotency from fibroblasts using defined factors. Microarray analysis was performed during reprogramming or of iPSC lines derived upon Sumo2 knockdown Total RNA was isolated from day 6 reprogramming fibroblasts with or without Sumo2 knockdown; as well as stable iPSC clones derived from Sumo2 knockdown fibroblasts.
Project description:Small ubiquitin-like modifiers (SUMOs) are post-translational modifications that play crucial roles in most cellular processes. While methods exist to study exogenous SUMOylation, large-scale characterization of endogenous SUMO has remained technically daunting. Here, we describe a proteomics approach facilitating system-wide and in vivo identification of lysines modified by endogenous and native SUMO2/3. We identified 14,869 endogenous SUMO sites in human cells during heat stress and proteasomal inhibition, and mapped 1,963 SUMO sites across eight mouse tissues; brain, heart, kidney, lung, liver, muscle, spleen, and testis. Quantification of the SUMO equilibrium highlighted striking differences in SUMO metabolism, between cells and tissues. Targeting preferences of SUMO varied across different organ types, coinciding with markedly differential SUMOylation states of all enzymes involved in the SUMO conjugation cascade. Collectively, our systemic investigation details the SUMOylation architecture across species and organs and provides a resource of endogenous SUMOylation sites on factors important in organ-specific functions and disease.
Project description:Purpose: To determine SUMO1 and SUMO2 chromatin profile in a static and dynamic manner in BMDC before and after LPS stimulation, and to determine RNAPolII chromatin occupancy in sumoylation-deficient BMDC compared to wild-type cells. Methods: SUMO1, SUMO2 and RNAPolII chromatin profiles were determined by sequencing BMDC chromatin immunoprecipitated with antibodies specific for SUMO1, SUMO2 and RNAPolII before and after LPS stimulation. Results: We show dynamic occupancy of three distal sites upstream of Ifnb1 gene by SUMO1 and SUMO2, as well as increased RNAPolII recruitment on selected genes. Conclusions: SUMO acts as a regulator of inflammatory and anti-viral gene programs. A study of SUMO and RNAPolII chromatin profile in Bone Marrow derived Dendritic Cells.
Project description:The generation of induced pluripotent stem cells (iPSCs) from differentiated cells following forced expression of Oct4, Klf4, Sox2 and c-Myc (OKSM) is slow and inefficient, suggesting that transcription factors have to overcome somatic barriers that resist cell fate change. Here, we performed an ubiased serial shRNA enrichment screen to identify novel repressors of somatic cell reprogramming into iPSCs. This effort uncovered the sumoylation effector protein Sumo2 as one of the strongest roadblocks to iPSC formation. Depletion of Sumo2 both enhances and accelerates reprogramming, yielding transgene-independent, chimera-competent iPSCs after as little as 36 hours of OKSM expression. We further show that the Sumo2 pathway acts independently of exogenous c-Myc expression and in parallel with small molecule enhancers of reprogramming. Critically, suppression of SUMO2 also promotes the generation of human iPSCs. Together, our results reveal sumoylation as a crucial post-transcriptional mechanism that resists the acquisition of pluripotency from fibroblasts using defined factors. Microarray analysis was performed during reprogramming or of iPSC lines derived upon Sumo2 knockdown