Project description:The deubiquitinase activity of Bap1 modifies osteoclast function by metabolic reprogramming. Bap1 deficient osteoclast lineage cells upregulate the cystine transporter, Slc7a11, by enhanced H2Aub occupancy of its promoter. SLC7A11 controls cellular ROS levels and redirects the mitochondrial metabolites away from the TCA cycle, both of which are necessary for osteoclast function.
Project description:Inactivating mutations of BAP1 are linked with an increased risk of developing metastasis in UM, but the roles of BAP1 in UM progression is unclear. To characterize BAP1’s functions in UM, we performed RNA sequencing on BAP1 wild-type and mutant UM cell lines. Gene set enrichment analysis showed that there is metabolic heterogeneity in BAP1 mutant UM cells based on their oxidative phosphorylation gene signature.
Project description:Supplemental data for the article: Characterization of functional reprogramming during osteoclast development using quantitative proteomics and mRNA profiling Eunkyung An, Manikandan Narayanan, and Aleksandra Nita-Lazar* *corresponding author: Cellular Networks Proteomics Unit Laboratory of Systems Biology National Institute of Allergy and Infectious Diseases National Institutes of Health Bethesda, Maryland, 20892, USA Tel. +1 301-451-4394 Fax: +1 301-480-5170 E-mail: nitalazarau@niaid.nih.gov This dataset includes: 1. Raw LC-MS(/MS) spectra (*.raw), and 2. The output from data analyses using IP2 (Intergrated Proteomics Application, San Diego, CA) searched against the UniProt_mouse_01-18-2011 set of protein sequences (normal + reversed). Note that the version of IP2 that was used could only analyze two SILAC channels at a time, so two analyses were performed (light-medium, light-heavy) (the current version can analyze 3-plex SILAC all together in one analysis). Also, IP2 was run using two criteria (1 or 2 peptides per protein). Lanes D and E were lanes of an SDS-PAGE gel, and each was 3-plex SILAC: Lane D: Light (Osteoclast Precursor), Medium (Mature Osteoclast), Heavy (Intermediate Osteoclast) Lane E: Light (Osteoclast Precursor), Medium (Intermediate Osteoclast), Heavy (Mature Osteoclast)
Project description:Enhanced osteoclastogenesis and osteoclast activity contribute to the development of osteoporosis, which is characterized by increased bone resorption and inadequate bone formation. As novel anti-osteoporotic therapeutics are needed, understanding the genetic regulation of human osteoclastogenesis could help identify potential treatment targets. This study aimed to provide an overview of the transcriptional reprogramming during human osteoclast differentiation. Osteoclasts were differentiated from CD14+-monocytes from eight female donors. RNA-sequencing during differentiation demonstrated 8980 differentially expressed genes grouped into eight temporal patterns conserved across donors. These patterns showed distinct molecular functions, associated with postmenopausal osteoporosis susceptibility genes based on RNA from iliac crest biopsies, and bone mineral density SNPs. Network analyses showed mutual dependencies between the temporal expression patterns and provides insight into subtype-specific transcriptional networks. Donor specific expression patterns identified genes at monocyte stage, such as filamin B (FLNB) and oxidized low density lipoprotein receptor 1 (OLR1, encoding LOX-1), that are predictive for the resorptive activity of mature osteoclasts. Differentially expressed G-protein coupled receptors showed strong expression during osteoclast differentiation and associated with bone mineral density SNPs, implying a pivotal role in osteoclast differentiation and activity. The regulatory effects of three differentially expressed G-protein coupled receptors were exemplified by in vitro pharmacological modulation of complement 5A receptor 1 (C5AR1), somatostatin receptor 2 (SSTR2), and free fatty acid receptor 4 (FFAR4/GPR120). Activating C5AR1 enhanced osteoclast formation, while activating SSTR2 decreased resorptive activity of mature osteoclasts, and activating FFAR4 decreased both number and resorptive activity of mature osteoclasts. In conclusion, we report the transcriptional reprogramming during human osteoclast differentiation and identified SSTR2 and FFAR4 as anti-resorptive G-protein coupled receptors as well as FLNB and LOX-1 as potential molecular markers of osteoclast activity. These data can help future investigations to identify molecular regulators of osteoclast differentiation and activity and provide the basis for novel anti-osteoporotic targets.
Project description:In Drosophila, a complex consisting of Calypso and ASX catalyzes H2A deubiquitination and has been reported to act as part of the Polycomb machinery in transcriptional silencing. The mammalian homologs of these proteins (BAP1 and ASXL1/2/3, respectively), are frequently mutated in various cancer types, yet their precise functions remain unclear. Using an integrative approach based on isogenic cell lines generated with CRISPR/Cas9, we uncover an unanticipated role for BAP1 in gene activation. This function requires the assembly of an enzymatically active BAP1-associated core complex (BAP1.com) containing one of the redundant ASXL proteins. We investigate the mechanism underlying BAP1.com-mediated transcriptional regulation and show that it does not participate in Polycomb-mediated silencing. Instead, our results establish that the function of BAP1.com is to safeguard transcriptionally active genes against silencing by the Polycomb Repressive Complex 1.
Project description:ASXL1 is the obligate regulatory subunit of a deubiquitinase complex whose catalytic subunit is BAP1. Heterozygous mutations of ASXL1 that result in premature truncations are frequent in myeloid leukemias and Bohring-Opitz syndrome. Here, we demonstrate that truncated ASXL1 proteins confer enhanced activity on the ASXL1-BAP1 complex. Stable expression of truncated, hyperactive ASXL1-BAP1 complexes in a hematopoietic precursor cell line resulted in global erasure of H2AK119Ub, striking depletion of H3K27me3, selective upregulation of a subset of genes whose promoters bore both H2AK119Ub and H3K4me3, and spontaneous differentiation to the mast cell lineage. These outcomes required the catalytic activity of BAP1, indicating these events were downstream consequences of H2AK119Ub erasure. In bone marrow precursors, truncated ASXL1-BAP1 expression cooperated with TET2 loss-of-function to increase differentiation to the myeloid lineage in vivo. We propose that pathological ASXL1 mutations confer gain-of-function on the ASXL-BAP1 complex. ChIP-Seq for H2AK119Ub, H3K4me3, H3K27me3 on EML cells. RNA-Seq on EML cells expressing ASXL1(1-479)+BAP1 and control.
Project description:The deubiquitinating enzyme BAP1 is a tumour suppressor, amongst others involved in cholangiocarcinoma. BAP1 has many proposed molecular targets, while its Drosophila homolog is known to deubiquitinate Histone H2AK119. Here, we mutate BAP1 by CRISPR/Cas9 in normal human liver organoids. We find that BAP1 controls the expression of junctional/cytoskeleton components by regulating chromatin accessibility. Consequently, we observe loss of multiple epithelial characteristics, while motility increases. Importantly, restoring the catalytic activity of BAP1 in the nucleus rescues these cellular and molecular changes. We engineer human liver organoids to combine four common cholangiocarcinoma mutations (TP53, PTEN, SMAD4, NF1). In this genetic background, BAP1 loss results in acquisition of malignant features upon xenotransplantation. Thus, control of epithelial identity through the regulation of chromatin accessibility appears a key aspect of BAP1’s tumour suppressor function. Organoid technology combined with CRISPR/Cas9 provides an experimental platform for mechanistic studies of cancer gene function in a human context.
Project description:The deubiquitinase BAP1 is a candidate tumor suppressor regulating cell proliferation in human and is required for development in Drosophila. BAP1 is assembled into high molecular weight transcriptional multi-protein complexes. In order to identify potential BAP1 target genes, global mRNA expression profiling using microarrays was conducted. U2OS cells, transfected with a non-target control shRNA or shRNAs targeting BAP1, were selected with puromycin containing medium and then synchronized at the G1/S border to allow comparative analysis of gene expression.
Project description:We report the genome wide binding sites of BAP1, HCF1 and OGT in bone marrow derived macrophages. De-ubiquitinating enzyme BAP1 is mutated in a hereditary cancer syndrome with increased risk of mesothelioma and uveal melanoma. Somatic BAP1 mutations occur in various malignancies. We show that mouse Bap1 gene deletion is lethal during embryogenesis, but systemic or hematopoietic-restricted deletion in adults recapitulates features of human myelodysplastic syndrome (MDS). Knockin mice expressing BAP1 with a 3xFlag tag revealed that BAP1 interacts with host cell factor–1 (HCF-1), O-linked N-acetylglucosamine transferase (OGT), and the polycomb group proteins ASXL1 and ASXL2 in vivo. OGT and HCF-1 levels were decreased by Bap1 deletion, indicating a critical role for BAP1 in stabilizing these epigenetic regulators. Human ASXL1 is mutated frequently in chronic myelomonocytic leukemia (CMML) so an ASXL/BAP1 complex may suppress CMML. A BAP1 catalytic mutation found in a MDS patient implies that BAP1 loss of function has similar consequences in mice and humans. For BAP1, bone marrow derived macrophages were used differentiated from bone marrow cells of BAP1-3X Flag Tagged KI mice we generated. For OGT and HCF1, bone marrow derived macrophages were used from BAP1 WT mice.