Modulating BAP1 expression affects ROS homeostasis, cell motility and mitochondrial function
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Lucie Hebert1, Dorine Bellanger1, Chloé Guillas1, Antoine Campagne2, Florent Dingli3, Damarys Loew3, Alice Fievet1,4, Virginie Jacquemin1, Tatiana Popova1, Didier Jean5, Fatima Mechta-Grigoriou1, Raphaël Margueron2 and Marc-Henri Stern1,4
1Department of Genetics and Biology of Cancers, INSERM U830, Institut Curie, PSL Research University, Paris 75248, France
2Department of Developmental Biology and Genetics, CNRS UMR 3215/INSERM U934, Institut Curie, PSL Research University, Paris 75248, France
3Mass Spectrometry and Proteomics facility, Institut Curie, PSL Research University, Paris 75248, France
4Department of Genetics, Institut Curie, Paris 75248, France
5INSERM UMR-1162, Paris 75010, France
Marc-Henri Stern, email: firstname.lastname@example.org
Keywords: BAP1, tumor suppressor, de-ubiquitination, proteomics, protein stability
Received: October 29, 2016 Accepted: July 23, 2017 Published: August 03, 2017
The tumor suppressor BAP1 associates with ASXL1/2 to form the core Polycomb complex PR-DUB, which catalyzes the removal of mono-ubiquitin from several substrates including histone H2A. This complex also mediates the poly-deubiquitination of HCFC1, OGT and PCG1-α, preventing them from proteasomal degradation. Surprisingly, considering its role in a Polycomb complex, no transcriptional signature was consistently found among BAP1-inactivated tumor types. It was hypothesized that BAP1 tumor suppressor activity could reside, at least in part, in stabilizing proteins through its poly-deubiquitinase activity. Quantitative mass spectrometry and gene expression arrays were used to investigate the consequences of BAP1 expression modulation in the NCI-H226 mesothelioma cell line. Analysis of differentially expressed proteins revealed enrichment in cytoskeleton organization, mitochondrial activity and ROS management, while gene expression analysis revealed enrichment in the epithelial-to-mesenchymal transition pathway. Functional assessments in BAP1 inactivated, BAP1 wild-type and BAP1 catalytically dead-expressing NCI-H226 and QR mesothelioma cell lines confirmed alteration of these pathways and demonstrated that BAP1 deubiquitinase activity was mandatory to maintain these phenotypes. Interestingly, monitoring intracellular ROS levels partly restored the morphology and the mitochondrial activity. Finally, the study suggests new tumorigenic and cellular functions of BAP1 and shows for the first time the interest of studying the proteome as readout of BAP1 inactivation.
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