A code of mono-phosphorylation modulates the function of RB.
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE116346 | GEO | 2019/02/01
REPOSITORIES: GEO
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Project description:The retinoblastoma tumor suppressor protein (Rb) regulates early G1 phase checkpoints, including the DNA damage response, as well as cell cycle exit and differentiation. The widely accepted model of G1 cell cycle progression proposes that cyclin D:Cdk4/6 partially inactivates the Rb tumor suppressor during early G1 phase by progressive multi-phosphorylation, termed hypo-phosphorylation, resulting in release of E2F transcription factors. However, this model remains largely unproven biochemically and the biologically active form(s) of Rb remains unknown. Here we find that Rb is un-phosphorylated in G0 cells and becomes exclusively mono-phosphorylated throughout all of early G1 phase by cyclin D:Cdk4/6. Early G1 phase mono-phosphorylated Rb is composed of 14 independent isoforms that are all targeted by the E1a oncoprotein, but each shows a preferential binding pattern to specific E2F1-4 transcription factors. At the late G1 Restriction Point, cyclin E:Cdk2 inactivates Rb by a quantum hyper-phosphorylation (>12 phosphates/Rb). Cells undergoing a DNA damage response activate cyclin D:Cdk4/6 to generate mono-phosphorylated Rb that regulates global transcription. In contrast, a non-phosphorylatable ?Cdk-Rb allele was non-functional for regulating a DNA damage response, but functional for driving cell cycle exit and differentiation during myogenesis. These observations fundamentally change our understanding of G1 cell cycle progression and show that there is no progressive multi-phosphorylation or hypo-phosphorylation inactivation of Rb during early G1 phase by cyclin D:Cdk4/6. Instead, cyclin D:Cdk4/6 generates functionally active, mono-phosphorylated Rb that is the only Rb isoform present in cells during early G1 phase. Global transcriptional analysis of murine embryonic fibroblasts (MEFs) with conditional deletion of the endogenous RB gene by treatment with cell permeable TAT-Cre. Comparison to unaltered MEFs and MEFs with physiological level of exogenous wildtype or phospho-mutant RB expressed at time of RB gene deletion.
2014-04-03 | E-GEOD-56453 | biostudies-arrayexpress
Project description:The retinoblastoma tumor suppressor protein (Rb) regulates early G1 phase checkpoints, including the DNA damage response, as well as cell cycle exit and differentiation. The widely accepted model of G1 cell cycle progression proposes that cyclin D:Cdk4/6 partially inactivates the Rb tumor suppressor during early G1 phase by progressive multi-phosphorylation, termed hypo-phosphorylation, resulting in release of E2F transcription factors. However, this model remains largely unproven biochemically and the biologically active form(s) of Rb remains unknown. Here we find that Rb is un-phosphorylated in G0 cells and becomes exclusively mono-phosphorylated throughout all of early G1 phase by cyclin D:Cdk4/6. Early G1 phase mono-phosphorylated Rb is composed of 14 independent isoforms that are all targeted by the E1a oncoprotein, but each shows a preferential binding pattern to specific E2F1-4 transcription factors. At the late G1 Restriction Point, cyclin E:Cdk2 inactivates Rb by a quantum hyper-phosphorylation (>12 phosphates/Rb). Cells undergoing a DNA damage response activate cyclin D:Cdk4/6 to generate mono-phosphorylated Rb that regulates global transcription. In contrast, a non-phosphorylatable ?Cdk-Rb allele was non-functional for regulating a DNA damage response, but functional for driving cell cycle exit and differentiation during myogenesis. These observations fundamentally change our understanding of G1 cell cycle progression and show that there is no progressive multi-phosphorylation or hypo-phosphorylation inactivation of Rb during early G1 phase by cyclin D:Cdk4/6. Instead, cyclin D:Cdk4/6 generates functionally active, mono-phosphorylated Rb that is the only Rb isoform present in cells during early G1 phase.
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Project description:Oncogenic transformation by adenovirus small e1a depends on simultaneous interactions with P300/CBP and RB proteins. To understand why, experiments with structure-based e1a mutants were analyzed with RNA- and ChIP-seq. The results indicate that e1a displaces RBs from E2F activation domains and, by promoting P300 acetylation of RB1 K873/K874, locks them into a repressing conformation that interacts with repressive chromatin modifying enzymes. e1a then delivers these repressing p300-e1a-RB1 complexes to cell genes that have unusually high P300 association with the gene body, enriched in genes of the TGFb-, TNF-, and IL1-signaling pathways. The P300-e1a-RB complex condenses chromatin, dependent on HDAC activity, P300 lysine acetylase activity, the P300 bromodomain, and acetylation of RB K873/K874 and e1a K239, contributing to repression of host genes that would otherwise inhibit cell cycling. The data suggest why e1a must bind P300/CBP as well as RBs for oncogenic transformation and why a trimeric P300-e1a-RB1 complex is required. Examination of transcriptome by mRNA sequencing before and after infection by adenoviral e1a expressing vectors in growth arrested IMR90
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Project description:Oncogenic transformation by adenovirus small e1a depends on simultaneous interactions with P300/CBP and RB proteins. To understand why, experiments with structure-based e1a mutants were analyzed with RNA- and ChIP-seq. The results indicate that e1a displaces RBs from E2F activation domains and, by promoting P300 acetylation of RB1 K873/K874, locks them into a repressing conformation that interacts with repressive chromatin modifying enzymes. e1a then delivers these repressing p300-e1a-RB1 complexes to cell genes that have unusually high P300 association with the gene body, enriched in genes of the TGFb-, TNF-, and IL1-signaling pathways. The P300-e1a-RB complex condenses chromatin, dependent on HDAC activity, P300 lysine acetylase activity, the P300 bromodomain, and acetylation of RB K873/K874 and e1a K239, contributing to repression of host genes that would otherwise inhibit cell cycling. The data suggest why e1a must bind P300/CBP as well as RBs for oncogenic transformation and why a trimeric P300-e1a-RB1 complex is required. Examination of RB1 rearrangements by adenoviral e1a in IMR90
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Project description:Oncogenic transformation by adenovirus small e1a depends on simultaneous interactions with P300/CBP and RB proteins. To understand why, experiments with structure-based e1a mutants were analyzed with RNA- and ChIP-seq. The results indicate that e1a displaces RBs from E2F activation domains and, by promoting P300 acetylation of RB1 K873/K874, locks them into a repressing conformation that interacts with repressive chromatin modifying enzymes. e1a then delivers these repressing p300-e1a-RB1 complexes to cell genes that have unusually high P300 association with the gene body, enriched in genes of the TGFb-, TNF-, and IL1-signaling pathways. The P300-e1a-RB complex condenses chromatin, dependent on HDAC activity, P300 lysine acetylase activity, the P300 bromodomain, and acetylation of RB K873/K874 and e1a K239, contributing to repression of host genes that would otherwise inhibit cell cycling. The data suggest why e1a must bind P300/CBP as well as RBs for oncogenic transformation and why a trimeric P300-e1a-RB1 complex is required. Chromatin IP background Input DNA for ChIP-seq normalization
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Project description:Oncogenic transformation by adenovirus small e1a depends on simultaneous interactions with P300/CBP and RB proteins. To understand why, experiments with structure-based e1a mutants were analyzed with RNA- and ChIP-seq. The results indicate that e1a displaces RBs from E2F activation domains and, by promoting P300 acetylation of RB1 K873/K874, locks them into a repressing conformation that interacts with repressive chromatin modifying enzymes. e1a then delivers these repressing p300-e1a-RB1 complexes to cell genes that have unusually high P300 association with the gene body, enriched in genes of the TGFb-, TNF-, and IL1-signaling pathways. The P300-e1a-RB complex condenses chromatin, dependent on HDAC activity, P300 lysine acetylase activity, the P300 bromodomain, and acetylation of RB K873/K874 and e1a K239, contributing to repression of host genes that would otherwise inhibit cell cycling. The data suggest why e1a must bind P300/CBP as well as RBs for oncogenic transformation and why a trimeric P300-e1a-RB1 complex is required. Examination of POL II rearrangements by adenoviral e1a in IMR90
2014-08-15 | E-GEOD-59691 | biostudies-arrayexpress
Project description:Oncogenic transformation by adenovirus small e1a depends on simultaneous interactions with P300/CBP and RB proteins. To understand why, experiments with structure-based e1a mutants were analyzed with RNA- and ChIP-seq. The results indicate that e1a displaces RBs from E2F activation domains and, by promoting P300 acetylation of RB1 K873/K874, locks them into a repressing conformation that interacts with repressive chromatin modifying enzymes. e1a then delivers these repressing p300-e1a-RB1 complexes to cell genes that have unusually high P300 association with the gene body, enriched in genes of the TGFb-, TNF-, and IL1-signaling pathways. The P300-e1a-RB complex condenses chromatin, dependent on HDAC activity, P300 lysine acetylase activity, the P300 bromodomain, and acetylation of RB K873/K874 and e1a K239, contributing to repression of host genes that would otherwise inhibit cell cycling. The data suggest why e1a must bind P300/CBP as well as RBs for oncogenic transformation and why a trimeric P300-e1a-RB1 complex is required. Examination of RB1 rearrangements by adenoviral e1a as well as mutant e1as in IMR90
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Project description:Oncogenic transformation by adenovirus small e1a depends on simultaneous interactions with P300/CBP and RB proteins. To understand why, experiments with structure-based e1a mutants were analyzed with RNA- and ChIP-seq. The results indicate that e1a displaces RBs from E2F activation domains and, by promoting P300 acetylation of RB1 K873/K874, locks them into a repressing conformation that interacts with repressive chromatin modifying enzymes. e1a then delivers these repressing p300-e1a-RB1 complexes to cell genes that have unusually high P300 association with the gene body, enriched in genes of the TGFb-, TNF-, and IL1-signaling pathways. The P300-e1a-RB complex condenses chromatin, dependent on HDAC activity, P300 lysine acetylase activity, the P300 bromodomain, and acetylation of RB K873/K874 and e1a K239, contributing to repression of host genes that would otherwise inhibit cell cycling. The data suggest why e1a must bind P300/CBP as well as RBs for oncogenic transformation and why a trimeric P300-e1a-RB1 complex is required. Examination of H3K27ac IMR90 before and after infection with dl1500
2014-08-15 | E-GEOD-59680 | biostudies-arrayexpress
Project description:Oncogenic transformation by adenovirus small e1a depends on simultaneous interactions with P300/CBP and RB proteins. To understand why, experiments with structure-based e1a mutants were analyzed with RNA- and ChIP-seq. The results indicate that e1a displaces RBs from E2F activation domains and, by promoting P300 acetylation of RB1 K873/K874, locks them into a repressing conformation that interacts with repressive chromatin modifying enzymes. e1a then delivers these repressing p300-e1a-RB1 complexes to cell genes that have unusually high P300 association with the gene body, enriched in genes of the TGFb-, TNF-, and IL1-signaling pathways. The P300-e1a-RB complex condenses chromatin, dependent on HDAC activity, P300 lysine acetylase activity, the P300 bromodomain, and acetylation of RB K873/K874 and e1a K239, contributing to repression of host genes that would otherwise inhibit cell cycling. The data suggest why e1a must bind P300/CBP as well as RBs for oncogenic transformation and why a trimeric P300-e1a-RB1 complex is required. Examination of P300 IMR90 before and after infection with dl1500
2014-08-15 | E-GEOD-59681 | biostudies-arrayexpress
Project description:Most E2F-binding sites repress transcription through the recruitment of Retinoblasoma (RB) family members until the end of the G1 cell-cycle phase. Although the MYB promoter contains an E2F-binding site, its transcription is activated shortly after the exit from quiescence, before RB family members inactivation, by unknown mechanisms. We had previously uncovered a nuclear factor distinct from E2F, Myb-sp, whose DNA-binding site overlapped the E2F element and had hypothesized that this factor might overcome the transcriptional repression of MYB by E2F-RB family members. We have purified Myb-sp and discovered that Myc-associated zinc finger proteins (MAZ) are major components. We show that various MAZ isoforms are present in Myb-sp and activate transcription via the MYB-E2F element. Moreover, while forced RB or p130 expression repressed the activity of a luciferase reporter driven by the MYB-E2F element, co-expression of MAZ proteins not only reverted repression, but also activated transcription. Finally, we show that MAZ binds the MYB promoter in vivo, that its binding site is critical for MYB transactivation, and that MAZ knockdown inhibits MYB expression during the exit from quiescence. Together, these data indicate that MAZ is essential to bypass MYB promoter repression by RB family members and to induce MYB expression.
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