Project description:Histone H2A monoubiquitination is associated with transcriptional repression and needs to be removed by deubiquitinases to facilitate gene transcription in eukaryotes. However, the deubiquitinase responsible for genome-wide H2A deubiquitination in plants has yet to be identified. We found that UBP5, an ubiquitin-specific protease, interacts with a previously identified PEAT (PWWP-EPCR-ARID-TRB) complex to form a larger version of PEAT complex in Arabidopsis thaliana. UBP5 functions as an H2A deubiquitinase in a nucleosome substrate-dependent manner in vitro and mediates H2A deubiquitination at the whole-genome level in vivo. Moreover, our results indicated that the histone acetyltransferases HAM1 and HAM2 (HAM1/2), catalytic subunits of the NuA4 histone acetyltransferase complex, are also part of the PEAT complex at PEAT target genomic loci. Within the PEAT complex, the PWWP components (PWWP1, PWWP2 and PWWP3) directly interact with UBP5 and are necessary for UBP5-mediated H2A deubiquitination, while the EPCR components (EPCR1 and EPCR2) directly interact with HAM1/2 and are required for HAM1/2-mediated H4K5 acetylation. This study identifies previously unknown regulators of H2A deubiquitination and H4K5 acetylation and illustrates how these processes collaborate at the whole-genome level.
Project description:Histone H2A monoubiquitination is associated with transcriptional repression and needs to be removed by deubiquitinases to facilitate gene transcription in eukaryotes. However, the deubiquitinase responsible for genome-wide H2A deubiquitination in plants has yet to be identified. We found that UBP5, an ubiquitin-specific protease, interacts with a previously identified PEAT (PWWP-EPCR-ARID-TRB) complex to form a larger version of PEAT complex in Arabidopsis thaliana. UBP5 functions as an H2A deubiquitinase in a nucleosome substrate-dependent manner in vitro and mediates H2A deubiquitination at the whole-genome level in vivo. Moreover, our results indicated that the histone acetyltransferases HAM1 and HAM2 (HAM1/2), catalytic subunits of the NuA4 histone acetyltransferase complex, are also part of the PEAT complex at PEAT target genomic loci. Within the PEAT complex, the PWWP components (PWWP1, PWWP2 and PWWP3) directly interact with UBP5 and are necessary for UBP5-mediated H2A deubiquitination, while the EPCR components (EPCR1 and EPCR2) directly interact with HAM1/2 and are required for HAM1/2-mediated H4K5 acetylation. This study identifies previously unknown regulators of H2A deubiquitination and H4K5 acetylation and illustrates how these processes collaborate at the whole-genome level.
Project description:Polycomb Repressive Complex 1 and histone H2A ubiquitination (ubH2A) contribute to embryonic stem cell (ESC) pluripotency by repressing lineage-specific gene expression. However, whether active deubiquitination co-regulates ubH2A levels in ESCs and during differentiation is not known. Here, we report that the histone H2A deubiquitinase Usp16 regulates H2A deubiquitination and gene expression in ESCs, and importantly, is required for ESC differentiation. Usp16 knockout is embryonic lethal in mice, but does not affect ESC viability or identity. Usp16 binds to the promoter regions of a large number of genes in ESCs and Usp16 binding is inversely correlated with ubH2A levels and positively correlated with gene expression levels. Intriguingly, Usp16-/- ESCs fail to differentiate due to ubH2A-mediated repression of lineage-specific genes. Finally, Usp16, but not the enzymatically inactive mutant, rescues the differentiation defects of Usp16-/- ESCs. Therefore, this study identifies Usp16 and H2A deubiquitination as critical regulators of ESC gene expression and differentiation. Examination of binding pattern of H2A deubiquitinase Usp16 and ubH2A in mouse embryonic stem cells and embroid bodies
Project description:Polycomb Repressive Complex 1 and histone H2A ubiquitination (ubH2A) contribute to embryonic stem cell (ESC) pluripotency by repressing lineage-specific gene expression. However, whether active deubiquitination co-regulates ubH2A levels in ESCs and during differentiation is not known. Here, we report that the histone H2A deubiquitinase Usp16 regulates H2A deubiquitination and gene expression in ESCs, and importantly, is required for ESC differentiation. Usp16 knockout is embryonic lethal in mice, but does not affect ESC viability or identity. Usp16 binds to the promoter regions of a large number of genes in ESCs and Usp16 binding is inversely correlated with ubH2A levels and positively correlated with gene expression levels. Intriguingly, Usp16-/- ESCs fail to differentiate due to ubH2A-mediated repression of lineage-specific genes. Finally, Usp16, but not the enzymatically inactive mutant, rescues the differentiation defects of Usp16-/- ESCs. Therefore, this study identifies Usp16 and H2A deubiquitination as critical regulators of ESC gene expression and differentiation.
Project description:In addition to acetylation, histones are modified by a series of competing longer chain acylations. Most of these acylation marks are enriched and co-exist with acetylation on active gene regulatory elements. Their seemingly redundant functions have hindered the understanding of histone acylations’ specific roles. Here, by using an acute lymphoblastic leukaemia (ALL) cell model and blasts from B-ALL patients, we demonstrate a role for mitochondrial activity in controlling histone acylation/acetylation ratio, especially at H4K5. An increase of the crotonylation and butyrylation over acetylation on H4K5 weakens BRD4-chromatin interaction and increases BRD4 nuclear mobility and availability for binding transcription start site associated nucleosome free regions of active genes. Our data suggest that, with regard to BRD4 dynamics, histone acylations including acetylation, should be considered collectively. A metabolism dependant control of the histone acetylation/longer chain acylation(s) ratio could constitute a common mechanism regulating bromodomain factors’ “reservoir” pool, availability and functional genomic distribution.
Project description:In addition to acetylation, histones are modified by a series of competing longer chain acylations. Most of these acylation marks are enriched and co-exist with acetylation on active gene regulatory elements. Their seemingly redundant functions have hindered the understanding of histone acylations’ specific roles. Here, by using an acute lymphoblastic leukaemia (ALL) cell model and blasts from B-ALL patients, we demonstrate a role for mitochondrial activity in controlling histone acylation/acetylation ratio, especially at H4K5. An increase of the crotonylation and butyrylation over acetylation on H4K5 weakens BRD4-chromatin interaction and increases BRD4 nuclear mobility and availability for binding transcription start site associated nucleosome free regions of active genes. Our data suggest that, with regard to BRD4 dynamics, histone acylations including acetylation, should be considered collectively. A metabolism dependant control of the histone acetylation/longer chain acylation(s) ratio could constitute a common mechanism regulating bromodomain factors’ “reservoir” pool, availability and functional genomic distribution.
Project description:In addition to acetylation, histones are modified by a series of competing longer chain acylations. Most of these acylation marks are enriched and co-exist with acetylation on active gene regulatory elements. Their seemingly redundant functions have hindered the understanding of histone acylations’ specific roles. Here, by using an acute lymphoblastic leukaemia (ALL) cell model and blasts from B-ALL patients, we demonstrate a role for mitochondrial activity in controlling histone acylation/acetylation ratio, especially at H4K5. An increase of the crotonylation and butyrylation over acetylation on H4K5 weakens BRD4-chromatin interaction and increases BRD4 nuclear mobility and availability for binding transcription start site associated nucleosome free regions of active genes. Our data suggest that, with regard to BRD4 dynamics, histone acylations including acetylation, should be considered collectively. A metabolism dependant control of the histone acetylation/longer chain acylation(s) ratio could constitute a common mechanism regulating bromodomain factors’ “reservoir” pool, availability and functional genomic distribution.