AMBRA1 interactome in ATRT cellular Model
Ontology highlight
ABSTRACT:
INSTRUMENT(S): Orbitrap Fusion
ORGANISM(S): Homo Sapiens (human)
TISSUE(S): Epithelial Cell, Cell Culture
DISEASE(S): Brain Cancer
SUBMITTER: 
Mohamed Ali Jarboui
LAB HEAD: Mohamed Ali Jarboui
PROVIDER: PXD043369 | Pride | 2023-10-10
REPOSITORIES: pride
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Project description:The initiation of cell division integrates a large number of intra- and extracellular inputs. D-type cyclins (hereafter, cyclin D) couple these inputs to the initiation of DNA replication1. Increased levels of cyclin D promote cell division by activating cyclin-dependent kinases 4 and 6 (hereafter, CDK4/6), which in turn phosphorylate and inactivate the retinoblastoma tumour suppressor. Accordingly, increased levels and activity of cyclin D-CDK4/6 complexes are strongly linked to unchecked cell proliferation and cancer2,3. However, the mechanisms that regulate levels of cyclin D are incompletely understood4,5. Here we show that autophagy and beclin 1 regulator 1 (AMBRA1) is the main regulator of the degradation of cyclin D. We identified AMBRA1 in a genome-wide screen to investigate the genetic basis of the response to CDK4/6 inhibition. Loss of AMBRA1 results in high levels of cyclin D in cells and in mice, which promotes proliferation and decreases sensitivity to CDK4/6 inhibition. Mechanistically, AMBRA1 mediates ubiquitylation and proteasomal degradation of cyclin D as a substrate receptor for the cullin 4 E3 ligase complex. Loss of AMBRA1 enhances the growth of lung adenocarcinoma in a mouse model, and low levels of AMBRA1 correlate with worse survival in patients with lung adenocarcinoma. Thus, AMBRA1 regulates cellular levels of cyclin D, and contributes to cancer development and the response of cancer cells to CDK4/6 inhibitors.
2021-02-04 | GSE146303 | GEO
Project description:The initiation of cell division is a fundamental process that integrates a large number of intra- and extra-cellular inputs. In mammalian cells, D-type cyclins (Cyclin D) couple these inputs to the decision to initiate DNA replication. Increased levels of Cyclin D promote cell cycle progression by activating cyclin-dependent kinases 4 and 6 (CDK4/6). Accordingly, increased levels and activity of Cyclin D and their associated kinases are strongly linked to unchecked cell proliferation and tumor development. Despite this central role of Cyclin D in cell cycle progression, the mechanisms regulating their levels remain incompletely understood. Here we describe AMBRA1 as the main regulator of Cyclin D protein degradation. We first identify AMBRA1 as the top candidate in a genome-wide CRISPR/Cas9 loss-of-function screen investigating the genetic basis of resistance to chemical CDK4/6 inhibition. AMBRA1 loss results in high protein levels of Cyclin D in cells and in mice. AMBRA1 loss further promotes lung cancer development in a mouse model, and low levels of AMBRA1 correlate with worse survival in lung cancer patients. Mechanistically, AMBRA1 acts as a substrate receptor for the Cullin 4 E3 ligase complex to promote ubiquitylation and proteasomal degradation of the three Cyclin D family members. Thus, AMBRA1 regulates Cyclin D protein levels and contributes to the development of cancer as well as the response of cancer cells to CDK4/6 inhibitors.
2021-02-05 | GSE159920 | GEO
Project description:The initiation of cell division is a fundamental process that integrates a large number of intra- and extra-cellular inputs. In mammalian cells, D-type cyclins (Cyclin D) couple these inputs to the decision to initiate DNA replication. Increased levels of Cyclin D promote cell cycle progression by activating cyclin-dependent kinases 4 and 6 (CDK4/6). Accordingly, increased levels and activity of Cyclin D and their associated kinases are strongly linked to unchecked cell proliferation and tumor development. Despite this central role of Cyclin D in cell cycle progression, the mechanisms regulating their levels remain incompletely understood. Here we describe AMBRA1 as the main regulator of Cyclin D protein degradation. We first identify AMBRA1 as the top candidate in a genome-wide CRISPR/Cas9 loss-of-function screen investigating the genetic basis of resistance to chemical CDK4/6 inhibition. AMBRA1 loss results in high protein levels of Cyclin D in cells and in mice. AMBRA1 loss further promotes lung cancer development in a mouse model, and low levels of AMBRA1 correlate with worse survival in lung cancer patients. Mechanistically, AMBRA1 acts as a substrate receptor for the Cullin 4 E3 ligase complex to promote ubiquitylation and proteasomal degradation of the three Cyclin D family members. Thus, AMBRA1 regulates Cyclin D protein levels and contributes to the development of cancer as well as the response of cancer cells to CDK4/6 inhibitors.
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Project description:Medulloblastoma (MB) is a childhood malignant brain tumour comprising four main subgroups characterized by different genetic alterations and rate of mortality. Among MB subgroups, patients with enhanced levels of the c-MYC oncogene (MBGroup3) have the poorest prognosis. Here we identified a previously unrecognized role of the pro-autophagy factor AMBRA1 in regulating MB. We demonstrated that AMBRA1 expression levels strongly depend on c-MYC expression and correlate with patient poor prognosis; also, knockdown of AMBRA1 reduces MB stem potential, growth and migration of MBGroup3 cells in vitro and in vivo. At a molecular level, AMBRA1 mediates these effects by suppressing SOCS3, an inhibitor of STAT3 activation. In turn, active STAT3 increases c-MYC expression that, in a positive feedback loop, sustains AMBRA1 transcription. Importantly, pharmacological inhibition of autophagy profoundly affects stem potential and metastasization of MBGroup3 cells in vitro and in vivo, and a combined anti-autophagy and anti-STAT3 approach impacts MBGroup3 cell survival. Taken together, our data identified the c-MYC/AMBRA1/STAT3 axis as a strong oncogenic signalling pathway with significance for both patient stratification strategies and targeted treatments of MBGroup3.
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Project description:AMBRA1 is a tumor suppressor protein that functions as a substrate receptor of the ubiquitin conjugation system with roles in autophagy and the cell cycle regulatory network. The intrinsic disorder of AMBRA1 has thus far precluded its structural determination. To solve this problem, we analyzed the dynamics of AMBRA1 using hydrogen deuterium exchange mass spectrometry (HDX-MS). The HDX results indicated that AMBRA1 is a highly flexible protein and can be stabilized upon interaction with DDB1, the adaptor of the Cullin4A/B E3 ligase. Here, we present the cryo-EM structure of AMBRA1 in complex with DDB1 at 3.08 Å resolution. The structure shows that parts of the N- and C-terminal structural regions in AMBRA1 fold together into the highly dynamic WD40 domain and reveals how DDB1 engages with AMBRA1 to create a binding scaffold for substrate recruitment. The N-terminal helix-loop-helix motif and WD40 domain of AMBRA1 associate with the double-propeller fold of DDB1. We also demonstrate that DDB1 binding-defective AMBRA1 mutants prevent ubiquitination of the substrate Cyclin D1 in vitro and increase cell cycle progression. Together, these results provide structural insights into the AMBRA1-ubiquitin ligase complex and suggest a mechanism by which AMBRA1 acts as a hub involved in various physiological processes.
2023-11-16 | PXD046056 | Pride
Project description:Here, using mouse squamous cell carcinoma cells, we report a completely new function for the autophagy protein Ambra1 as the first described ‘spatial rheostat’ controlling the Src/FAK pathway. Ambra1 regulates the targeting of active phospho-Src away from focal adhesions into autophagic structures that cancer cells use to survive adhesion stress. Ambra1 binds to both FAK and Src in cancer cells. When FAK is present, Ambra1 is recruited to focal adhesions, promoting FAK-regulated cancer cell direction-sensing and invasion. However, when Ambra1 cannot bind to FAK, abnormally high levels of phospho-Src and phospho-FAK accumulate at focal adhesions, positively regulating adhesion and invasive migration. Spatial control of active Src requires the trafficking proteins Dynactin 1 and IFITM3, which we identified as Ambra1 binding partners by interaction proteomics. We conclude that Ambra1 is a core component of an intracellular trafficking network linked to tight spatial control of active Src and FAK levels, and so crucially regulates their cancer-associated biological outputs.
2017-04-04 | PXD006002 | Pride
Project description:Melanoma is the most deadly type of skin cancers and, there is a continuous need to develop early biomarkers as well as treatments to improve the survivability of patients. Ambra1 is an essential regulator in autophagy and it has been recently shown to have a role in cell proliferation. We used microarrays to analyse the transcriptomic changesi n A375 melanoma cell lines following Ambra1 differential expression
2021-05-23 | GSE175361 | GEO
Project description:Here we describe AMBRA1 as the main regulator of Cyclin D protein degradation. We first identify AMBRA1 as the top candidate in a genome-wide CRISPR/Cas9 loss-of-function screen investigating the genetic basis of resistance to chemical CDK4/6 inhibition. AMBRA1 loss results in high protein levels of Cyclin D in cells and in mice. AMBRA1 loss further promotes lung cancer development in a mouse model, and low levels of AMBRA1 correlate with worse survival in lung cancer patients. Mechanistically, AMBRA1 acts as a substrate receptor for the Cullin 4 E3 ligase complex to promote ubiquitylation and proteasomal degradation of the three Cyclin D family members. Thus, AMBRA1 regulates Cyclin D protein levels and contributes to the development of cancer as well as the response of cancer cells to CDK4/6 inhibitors.
2021-07-24 | PXD021789 | Pride
Project description:We sought to identify AMBRA1 interacting proteins and to profile its loss/gain of interactions by mutation using quantitative mass spectrometry.
2018-07-11 | PXD008005 | Pride
Project description:Previously, we reported that Ambra1 is a core component of a cytoplasmic trafficking network, acting as a spatial rheostat to control active Src and FAK levels in addition to its critical roles in autophagy during neurogenesis. Here we identify a novel nuclear scaffolding function for Ambra1 that controls gene expression. Ambra1 binds to nuclear pore proteins, to other adaptor proteins like FAK and Akap8 in the nucleus, as well as to chromatin modifiers and transcriptional regulators such as Brg1, Cdk9 and the cAMP-regulated transcription factor Atf2. Ambra1 contributes to their association with chromatin and we identified genes whose transcription is regulated by Ambra1 complexes, likely via histone modifications and phospho-Atf2-dependent transcription. Therefore, Ambra1 scaffolds protein complexes at chromatin, regulating transcriptional signalling in the nucleus; in particular, it recruits chromatin modifiers and transcriptional regulators to control expression of genes such as Angpt1, Tgfb2, Tgfb3, Itga8 and Itgb7 that likely contribute to the role of Ambra1 in cancer cell invasion.
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