Project description:Macrophage activation during the innate immune response is tightly regulated to prevent tissue damage while activating the defense to cellular attack. Using a mouse model where Trim33 is specifically deleted in mature myeloid cells, we show that TRIM33 is essential for two aspects of the inflammatory response in vivo. Loss of TRIM33 attenuates the initiation of macrophage activation by lipopolysaccharide (LPS) and TRIM33 is necessary to switch off transcription of inflammatory genes during late stages of LPS activation. Using chromatin immunoprecipitation coupled to deep sequencing, we provide a link between TRIM33 binding, RNA Polymerase II occupancy and H3K4me3 spreading on inflammatory genes in macrophages and reveal novel insights concerning the transcriptional regulation of Ifn-beta where TRIM33 exerts a repressive function via a distal regulatory region during late stages of LPS activation of macrophages. These findings pinpoint TRIM33 as a major regulator of the resolution of inflammation and indicate that transcriptional regulators can fine-tune H3K4me3 spreading. To study the role of TRIM33 in the transcriptional response induced by pathogen receptors, we analyzed whether lack of TRIM33 in macrophages affected the TLR-mediated regulation of proinflammatory and antimicrobial genes. To study this role, we bred TRIM33fl/fl mice with Lyz-Cre mice (obtained from The Jackson Laboratory, Bar Harbor, Maine, USA) where the Cre recombinase gene is under the regulatory sequences of the Lyz gene that is expressed only in mature myeloid cells. Bone marrow cells from 2 LyzCre/Trim33+/+ mice and 2 LyzCre/Trim33flox/flox mice were then differentiated in macrophages and treated during 0h, 4h, 12h and 24h with LPS. Total RNA was extracted from macrophages and analysed using cDNA microarrays. The set of gene expression consists of 16 samples of RNA of bone marrow derived macrophages activated with 100ng/ml of LPS during 0h, 4h, 12h, 24h, 8 samples from 2 LyzCre/Trim33+/+ mice and 8 samples from 2 LyzCre/Trim33flox/flox mice.
Project description:To get insight into TRIM33 functions, TRIM33 ChIP-seq was carried out in murine macrophage cell line (RAW) and in bone marrow-derived macrophages (BMDM). The results showed that, in addition to its role in hematopoietic differentiation, TRIM33 may modulate PU.1 transcriptional activity during macrophage development and/or activation.To characterize the role of TRIM33 in macrophages, we bred TRIM33fl/fl mice with Lyz-Cre mice where the Cre recombinase gene is under the regulatory sequences of the Lyz gene that is expressed only in mature myeloid cells. Bone marrow cells from LyzCre/Trim33+/+ mice and LyzCre/Trim33flox/flox mice were differentiated in macrophages and treated during 0h, 4h, 12h and 24h with LPS. Using ChIP-seq, we provide a link between TRIM33 binding and H3K4me3 spreading on inflammatory genes in macrophages. Chromatin immunoprecipitations of TRIM33 and H3K4Me3 followed by multiparallel sequencing performed in murine bone marrow-derived macrophages (BMDM).
Project description:Despite its importance during viral or bacterial infections, transcriptional regulation of the interferon-b gene (Ifnb1) in activated macrophages is only partially understood. Here we report that TRIM33 deficiency results in high-sustained expression of Ifnb1 at late stages of toll-like receptor-mediated activation in macrophages but not in fibroblasts. In macrophages, TRIM33 is recruited by PU.1 to a conserved region, Ifnb1 Control Element (ICE), located 15kb upstream of the Ifnb1 transcription start site. ICE constitutively interacts with Ifnb1 through a TRIM33-independent chromatin loop. At late phases of lipopolysaccharide activation of macrophages, TRIM33 is bound to ICE, regulates Ifnb1 enhanceosome loading, controls Ifnb1 chromatin structure, and represses Ifnb1 gene transcription by preventing recruitment of CBP/p300. These results characterize a previously unknown mechanism of macrophage-specific regulation of Ifnb1 transcription whereby TRIM33 is critical for Ifnb1 gene transcription shut down.
Project description:Deregulation of RNA polymerase II (RNAPII) by oncoproteins, such as transcription factor Myc, interferes with DNA replication and is a major source of DNA damage and genomic instability. Ubiquitination is a key pathway controlling RNAPII activity via modification of RNAPII subunits or associated regulatory proteins. We uncover a mechanism for genome maintenance by ubiquitin ligase Trim33 and transcription factor E2f4. We show that Trim33 promotes E2f4 protein turnover, restricting interactions of E2f4 with chromatin and with the Recql DNA helicase. Replicative stress blunts Trim33-dependent regulation, which stimulates E2f4 and Recql recruitment to chromatin and facilitates recovery of DNA replication. Deletion of Trim33 triggers chronic recruitment of Recql to chromatin and accelerates DNA replication under stress, accompanied by compromised DDR signaling and DNA repair. Depletion of Trim33 in Myc-overexpressing cells leads to accumulation of replication-associated DNA damage and delays Myc-driven tumorigenesis. We propose that the Trim33-E2f4-Recql axis provides a mechanism to control DNA replication at transcriptionally active chromatin to maintain genome integrity.
Project description:To get insight into TRIM33 functions, TRIM33 ChIP-seq was carried out in murine macrophage cell line (RAW) and in bone marrow-derived macrophages (BMDM). The results showed that, in addition to its role in hematopoietic differentiation, TRIM33 may modulate PU.1 transcriptional activity during macrophage development and/or activation.To characterize the role of TRIM33 in macrophages, we bred TRIM33fl/fl mice with Lyz-Cre mice where the Cre recombinase gene is under the regulatory sequences of the Lyz gene that is expressed only in mature myeloid cells. Bone marrow cells from LyzCre/Trim33+/+ mice and LyzCre/Trim33flox/flox mice were differentiated in macrophages and treated during 0h, 4h, 12h and 24h with LPS. Using ChIP-seq, we provide a link between TRIM33 binding and H3K4me3 spreading on inflammatory genes in macrophages.
Project description:Although the advances in genome-wide approaches have elucidated the functions of macrophage-specific distal regulatory elements in transcriptional responses, chromatin structures associated with PU.1 priming and the underlying mechanisms of action of these cis-acting sequences are not characterized. Here, we show that, in macrophages, FACT subunit SPT16 can bind to positioned nucleosomes directly flanking PU.1-bound sites at previously uncharacterized distal regulatory elements located near genes essential for macrophage development and functions. SPT16 can interact with the transcriptional co-regulator TRIM33 and binds to half of these sites in a TRIM33 dependent manner. Using the Atp1b3 locus as a model, we show that FACT binds to two positioned nucleosomes surrounding a TRIM33/PU.1-bound site in a region, located 35kb upstream the Atp1b3 TSS, that interact with the Atp1b3 promoter. At this -35kb region, TRIM33 deficiency leads to FACT release, loss of the two positioned nucleosomes, RNA Pol II recruitment and bidirectional transcription. These modifications are associated with higher levels of FACT binding at the Atp1b3 promoter, an increase of RNA Pol II recruitment and an increased expression of Atp1b3 in Trim33-/- macrophages. Thus, sequestering of SPT16/FACT by TRIM33 at PU.1-bound distal regions might represent a new regulatory mechanism for RNA Pol II recruitment and transcription output in macrophages.
Project description:Although the advances in genome-wide approaches have elucidated the functions of macrophage-specific distal regulatory elements in transcriptional responses, chromatin structures associated with PU.1 priming and the underlying mechanisms of action of these cis-acting sequences are not characterized. Here, we show that, in macrophages, FACT subunit SPT16 can bind to positioned nucleosomes directly flanking PU.1-bound sites at previously uncharacterized distal regulatory elements located near genes essential for macrophage development and functions. SPT16 can interact with the transcriptional co-regulator TRIM33 and binds to half of these sites in a TRIM33 dependent manner. Using the Atp1b3 locus as a model, we show that FACT binds to two positioned nucleosomes surrounding a TRIM33/PU.1-bound site in a region, located 35kb upstream the Atp1b3 TSS, that interact with the Atp1b3 promoter. At this -35kb region, TRIM33 deficiency leads to FACT release, loss of the two positioned nucleosomes, RNA Pol II recruitment and bidirectional transcription. These modifications are associated with higher levels of FACT binding at the Atp1b3 promoter, an increase of RNA Pol II recruitment and an increased expression of Atp1b3 in Trim33-/- macrophages. Thus, sequestering of SPT16/FACT by TRIM33 at PU.1-bound distal regions might represent a new regulatory mechanism for RNA Pol II recruitment and transcription output in macrophages.
Project description:Deregulation of RNA polymerase II (RNAPII) by oncoproteins, such as transcription factor Myc, interferes with DNA replication and is a major source of DNA damage and genomic instability. Ubiquitination is a key pathway controlling RNAPII activity via modification of RNAPII subunits or associated regulatory proteins. We uncover a mechanism for genome maintenance by ubiquitin ligase Trim33 and transcription factor E2f4. We show that Trim33 promotes E2f4 protein turnover, restricting interactions of E2f4 with chromatin and with the Recql DNA helicase. Replicative stress blunts Trim33-dependent regulation, which stimulates Recql recruitment to chromatin and facilitates recovery of DNA synthesis. Deletion of Trim33 triggers chronic recruitment of Recql and accelerates DNA replication under stress, accompanied by compromised DDR signaling and DNA repair. Depletion of Trim33 in Myc-overexpressing cells leads to accumulation of replication-associated DNA damage and delays Myc-driven tumorigenesis. We propose that the Trim33-E2f4-Recql axis provides a mechanism to control DNA replication at transcriptionally active chromatin to maintain genome integrity.
Project description:Deregulation of RNA polymerase II (RNAPII) by oncoproteins, such as transcription factor Myc, interferes with DNA replication and is a major source of DNA damage and genomic instability. Ubiquitination is a key pathway controlling RNAPII activity via modification of RNAPII subunits or associated regulatory proteins. We uncover a mechanism for genome maintenance by ubiquitin ligase Trim33 and transcription factor E2f4. We show that Trim33 promotes E2f4 protein turnover, restricting interactions of E2f4 with chromatin and with the Recql DNA helicase. Replicative stress blunts Trim33-dependent regulation, which stimulates Recql recruitment to chromatin and facilitates recovery of DNA synthesis. Deletion of Trim33 triggers chronic recruitment of Recql and accelerates DNA replication under stress, accompanied by compromised DDR signaling and DNA repair. Depletion of Trim33 in Myc-overexpressing cells leads to accumulation of replication-associated DNA damage and delays Myc-driven tumorigenesis. We propose that the Trim33-E2f4-Recql axis provides a mechanism to control DNA replication at transcriptionally active chromatin to maintain genome integrity.
Project description:Deregulation of RNA polymerase II (RNAPII) by oncoproteins, such as transcription factor Myc, interferes with DNA replication and is a major source of DNA damage and genomic instability. Ubiquitination is a key pathway controlling RNAPII activity via modification of RNAPII subunits or associated regulatory proteins. We uncover a mechanism for genome maintenance by ubiquitin ligase Trim33 and transcription factor E2f4. We show that Trim33 promotes E2f4 protein turnover, restricting interactions of E2f4 with chromatin and with the Recql DNA helicase. Replicative stress blunts Trim33-dependent regulation, which stimulates Recql recruitment to chromatin and facilitates recovery of DNA synthesis. Deletion of Trim33 triggers chronic recruitment of Recql and accelerates DNA replication under stress, accompanied by compromised DDR signaling and DNA repair. Depletion of Trim33 in Myc-overexpressing cells leads to accumulation of replication-associated DNA damage and delays Myc-driven tumorigenesis. We propose that the Trim33-E2f4-Recql axis provides a mechanism to control DNA replication at transcriptionally active chromatin to maintain genome integrity.