Project description:Polycomb repressive complex 2 (PRC2) maintains repression of genes specific for other cell differentiation stages through methylation of histone H3 lysine 27 (H3K27me3) and is regulated by nascent RNA. In endometrial stromal sarcoma, the PRC2 subunit SUZ12 is often fused with the transcription factor JAZF1. How JAZF1-SUZ12 affects PRC2 function and cell differentiation are unknown. Here, we show that JAZF1-SUZ12 disrupts PRC2 recruitment, gene expression and cell differentiation. The loss of the SUZ12 N-terminus in the fusion protein disrupted interaction with JARID2, EPOP and PALI1 and prevented recruitment of PRC2 from RNA to chromatin. JAZF1-SUZ12 occupied PRC2 target genes in undifferentiated cells but relocated to JAZF1 target genes during cell differentiation, altering patterns of H3K27me3 and gene expression and disrupting cell differentiation. We then performed RNA-seq in primary human cells expreesing all proteins, showing that JAZF1-SUZ12 was promoting a specific set of genes upregulated in decidualisation, while blocking immune related genes. These results reveal the defects in PRC2 function and cell differentiation caused by the JAZF1-SUZ12 fusion protein, which may underlie its role in oncogenesis.
Project description:Alternative splicing of SUZ12 exon 4 is predicted to generate two alternative isoforms differing by the inclusion or exclusion of 69 nucleotides in exon 4, which we named SUZ12-long (SUZ12-L) and SUZ12-short (SUZ12-S) respectively. At the protein level SUZ12 exon 4 encodes 23 amino acids (aa 129–152 in SUZ12-L) that partially overlap with the WD-binding domain 1 (WDB1, 110–145). To detect the existance of SUZ12-S at the protein levels we performed SUZ12 immunoprecipitation coupled with mass spectrometry (IP-MS) in the WT and ∆ex4 clones to identify SUZ12-S unique peptides. We identified a SUZ12-S specific peptide in both WT #2 and ∆ex4 #1. These observations were confirmed by SUZ12 IP followed by Western blot (WB) (size shift).
Project description:Suz12 exon 4 encodes 23 amino acids (aa 129–152 in SUZ12-L) that partially overlap with the WD-binding domain 1 (WDB1, 110–145). We reasoned that exon 4 skipping might alter the structure of SUZ12 and, possibly, PRC2 composition. To explore this possibility, we generated ESCs that lack the Suz12 exon 4 via CRISPR-Cas9–induced deletion. In addition, to rule out any biases due to the expression levels and/or SUZ12 epitope masking, we generated Suz12 knockout (KO) ESCs (herein, KO) in which Suz12 expression was subsequently rescued by re-introducing either the Suz12-L or Suz12-S mouse isoform fused to a triple-Flag tag under the regulation of a CAG promoter (KO+L/S; Figures S2H–S2K). We performed SUZ12 immunoprecipitation coupled with mass spectrometry (IP-MS) in the WT and ∆ex4 clones to compare their interactomes and with a flag antibody in the KO and rescue cell lines. As expected, no peptides corresponding to exon 4 were retrieved in ∆ex4 samples, while the rest of the sequence displayed similar coverage. Comparison of interactors in the two conditions revealed that SUZ12 binding to AEBP2 and JARID2 was strongly reduced in ∆ex4 cells with respect to WT cells, whereas SUZ12 binding to most core components or to PRC2.1-specific factors was unchanged or only slightly increased . These observations were confirmed by SUZ12 IP followed by Western blot (WB). Flag IP-MS in rescue cells confirmed that, while the long isoform was able to correctly form comparable amounts of both PRC2.1 and PRC2.2 subtypes, interaction of the SUZ12-S with PRC2.2-specific factors was drastically reduced.
Project description:Endometrial stromal sarcomas (ESSs) are a genetically heterogeneous group of rare uterine neoplasms that are frequently driven by recurrent gene rearrangements. In conventional low-grade ESSs, JAZF1-SUZ12, PHF1-JAZF1, EPC1-PHF1 and MEAF6-PHF1 chimeric fusions have been reported in > 50% of cases. The recently described t(10;17)(q22;p13) translocation yields YWHAE-FAM22A/B chimeric proteins that are associated with histologically high-grade and clinically more aggressive ESS. Integrating whole-transcriptome paired-end RNA sequencing with fluorescence in situ hybridization (FISH) and conventional cytogenetics, we identified MBTD1 (Malignant Brain Tumor Domain-containing 1) and CXorf67 (Chromosome X open reading frame 67) as the genes involved in the novel reciprocal t(X;17)(p11.2;q21.33) translocation in two independent low-grade ESS of classical histology. The presence of the MBTD1-CXorf67 fusion transcript was validated in both cases using RT-PCR followed by Sanger sequencing. A specific FISH assay to be used on paraffin tissues was developed to detect the novel t(X;17) translocation, and resulted in identification of an additional low-grade ESS case positive for the MBTD1-CXorf67 fusion among 14 uterine stromal tumours [9 ESSs and 5 undifferentiated endometrial sarcomas (UESs)] that were negative for JAZF1 and YWHAE rearrangements. Gene expression profiles of 3 ESSs with YWHAE- and 4 classical ESSs with JAZF1-rearrangements, and 4 UESs without known gene rearrangements, indicated clustering of tumours with MBTD1-CXorf67 fusion together with low-grade JAZF1-associated ESSs. The chimeric MBTD1-CXorf67 fusion identifies yet another cytogenetically distinct subgroup of low-grade ESS and offers the opportunity to shed light on the functions of two poorly characterized genes. Genomic DNA extracted from 2 low-grade ESS frozen tumor samples; Agilent CGH+SNP 4x180K array. Reference female DNA supplied with the SureTag Complete DNA Labeling Kit was used for the aCGH experiments.
Project description:Endometrial stromal sarcomas (ESSs) are a genetically heterogeneous group of rare uterine neoplasms that are frequently driven by recurrent gene rearrangements. In conventional low-grade ESSs, JAZF1-SUZ12, PHF1-JAZF1, EPC1-PHF1 and MEAF6-PHF1 chimeric fusions have been reported in >50% of cases. The recently described t(10;17)(q22;p13) translocation yields YWHAE-FAM22A/B chimeric proteins that are associated with histologically high-grade and clinically more aggressive ESS. Integrating whole-transcriptome paired-end RNA sequencing with fluorescence in situ hybridization (FISH) and conventional cytogenetics, we identified MBTD1 (Malignant Brain Tumor Domain-containing 1) and CXorf67 (Chromosome X open reading frame 67) as the genes involved in the novel reciprocal t(X;17)(p11.2;q21.33) translocation in two independent low-grade ESS of classical histology. The presence of the MBTD1-CXorf67 fusion transcript was validated in both cases using RT-PCR followed by Sanger sequencing. A specific FISH assay to be used on paraffin tissues was developed to detect the novel t(X;17) translocation, and resulted in identification of an additional low-grade ESS case positive for the MBTD1-CXorf67 fusion among 14 uterine stromal tumours [9 ESSs and 5 undifferentiated endometrial sarcomas (UESs)] that were negative for JAZF1 and YWHAE rearrangements. Gene expression profiles of 3 ESSs with YWHAE- and 4 classical ESSs with JAZF1-rearrangements, and 4 UESs without known gene rearrangements, indicated clustering of tumours with MBTD1-CXorf67 fusion together with low-grade JAZF1-associated ESSs. The chimeric MBTD1-CXorf67 fusion identifies yet another cytogenetically distinct subgroup of low-grade ESS and offers the opportunity to shed light on the functions of two poorly characterized genes. Total RNA was extracted from 11 frozen tumor samples from 4 low-grade ESS cases, 4 UES cases and 3 high-grade ESS cases; Agilent One-Color technology.
Project description:Endometrial stromal sarcomas (ESSs) are a genetically heterogeneous group of rare uterine neoplasms that are frequently driven by recurrent gene rearrangements. In conventional low-grade ESSs, JAZF1-SUZ12, PHF1-JAZF1, EPC1-PHF1 and MEAF6-PHF1 chimeric fusions have been reported in > 50% of cases. The recently described t(10;17)(q22;p13) translocation yields YWHAE-FAM22A/B chimeric proteins that are associated with histologically high-grade and clinically more aggressive ESS. Integrating whole-transcriptome paired-end RNA sequencing with fluorescence in situ hybridization (FISH) and conventional cytogenetics, we identified MBTD1 (Malignant Brain Tumor Domain-containing 1) and CXorf67 (Chromosome X open reading frame 67) as the genes involved in the novel reciprocal t(X;17)(p11.2;q21.33) translocation in two independent low-grade ESS of classical histology. The presence of the MBTD1-CXorf67 fusion transcript was validated in both cases using RT-PCR followed by Sanger sequencing. A specific FISH assay to be used on paraffin tissues was developed to detect the novel t(X;17) translocation, and resulted in identification of an additional low-grade ESS case positive for the MBTD1-CXorf67 fusion among 14 uterine stromal tumours [9 ESSs and 5 undifferentiated endometrial sarcomas (UESs)] that were negative for JAZF1 and YWHAE rearrangements. Gene expression profiles of 3 ESSs with YWHAE- and 4 classical ESSs with JAZF1-rearrangements, and 4 UESs without known gene rearrangements, indicated clustering of tumours with MBTD1-CXorf67 fusion together with low-grade JAZF1-associated ESSs. The chimeric MBTD1-CXorf67 fusion identifies yet another cytogenetically distinct subgroup of low-grade ESS and offers the opportunity to shed light on the functions of two poorly characterized genes.
Project description:Endometrial stromal sarcomas (ESSs) are a genetically heterogeneous group of rare uterine neoplasms that are frequently driven by recurrent gene rearrangements. In conventional low-grade ESSs, JAZF1-SUZ12, PHF1-JAZF1, EPC1-PHF1 and MEAF6-PHF1 chimeric fusions have been reported in >50% of cases. The recently described t(10;17)(q22;p13) translocation yields YWHAE-FAM22A/B chimeric proteins that are associated with histologically high-grade and clinically more aggressive ESS. Integrating whole-transcriptome paired-end RNA sequencing with fluorescence in situ hybridization (FISH) and conventional cytogenetics, we identified MBTD1 (Malignant Brain Tumor Domain-containing 1) and CXorf67 (Chromosome X open reading frame 67) as the genes involved in the novel reciprocal t(X;17)(p11.2;q21.33) translocation in two independent low-grade ESS of classical histology. The presence of the MBTD1-CXorf67 fusion transcript was validated in both cases using RT-PCR followed by Sanger sequencing. A specific FISH assay to be used on paraffin tissues was developed to detect the novel t(X;17) translocation, and resulted in identification of an additional low-grade ESS case positive for the MBTD1-CXorf67 fusion among 14 uterine stromal tumours [9 ESSs and 5 undifferentiated endometrial sarcomas (UESs)] that were negative for JAZF1 and YWHAE rearrangements. Gene expression profiles of 3 ESSs with YWHAE- and 4 classical ESSs with JAZF1-rearrangements, and 4 UESs without known gene rearrangements, indicated clustering of tumours with MBTD1-CXorf67 fusion together with low-grade JAZF1-associated ESSs. The chimeric MBTD1-CXorf67 fusion identifies yet another cytogenetically distinct subgroup of low-grade ESS and offers the opportunity to shed light on the functions of two poorly characterized genes.
Project description:In this study, we characterize translocations that are frequent in Low Grade Endometrial Stromal Sarcoma (LG-ESS) and Ossifying FibroMyxoid Tumors (OFMT). We find that the fusion protein assembles a mega-complex harboring both NuA4/TIP60 and PRC2 subunits and enzymatic activities and leads to mislocalization of chromatin marks in the genome, linked to aberrant gene expression.
Project description:We investigate the contribution of each SUZ12 isoform on PRC2 activity on chromatin using our different ESC lines. As an additional comparison for ∆ex4 cells (SUZ12-S), we included an ESC clone in which an unsuccessful CRISPR editing event resulted in a mutant allele with nearly constitutive splicing of exon 4 (herein, CSex4) and normal Suz12 expression levels (expressing only SUZ12-L). First, we profiled H3K27 bulk PTMs by WB and observed that, while CSex4 cells showed no major differences to control cells, ∆ex4 cells displayed lower levels of H3K27me2 and -me3, with higher levels of mono-methylation and acetylation. Similar results were obtained when comparing SUZ12-L and SUZ12-S ESC rescue lines. To validate these findings with an antibody-independent technique, and to additionally profile other histone PTMs, we analysed these cells with histone-MS. In line with the previous estimates26, WT cells displayed approximately 85% of H3K27 methylation. This proportion was largely similar in CSex4 cells, while it dropped to ~50% in ∆ex4 cells, with H3K27me2 and -me3 being the most affected modifications. Notably, H3K27me2/3 loss in ∆ex4 cells occurred at histone peptides regardless of their H3K36 methylation status. Moreover, the global H3K36 methylation rates were not affected in either CSex4 or ∆ex4 cells (Figure S4C), and no major changes in methylation or acetylation levels were observed at other residues. Importantly, reintroduction of SUZ12-L in KO cells rescued a higher degree of methylation compared to SUZ12-S. Overall, these results indicate that SUZ12-S alone is unable to maintain global physiological levels of H3K27 methylation; rather SUZ12-L is also necessary for this task.