Project description:Structural genetic variants like copy number variants (CNVs) comprise a large part of human genetic variation and may be inherited as well as somatically acquired. Recent studies have reported the presence of somatically acquired structural variants in the human genome and it has been suggested that they may accumulate in elderly individuals. To further explore the presence and the age-related acquisition of somatic structural variants in the human genome, we investigated CNVs acquired over a period of 10 years in 86 elderly Danish twins as well as CNV discordances between co-twins of 18 monozygotic twin pairs. Furthermore, the presence of mosaic structural variants was explored.
Project description:Sustained expression of the estrogen receptor-α (ESR1) drives two-thirds of breast cancer and defines the ESR1-positive subtype. ESR1 engages enhancers upon estrogen stimulation to establish an oncogenic expression program1. Somatic copy number alterations involving the ESR1 gene occur in approximately 1 % of ESR1-positive breast cancers2â5, suggesting that other mechanisms underlie the persistent expression of ESR1. We report significant enrichment of somatic mutations within the set of regulatory elements (SRE) regulating ESR1 in 7% of ESR1-positive breast cancers. These mutations regulate ESR1 expression by modulating transcription factor binding to the DNA. The SRE includes a recurrently mutated enhancer whose activity is also affected by rs9383590, a functional inherited single-nucleotide variant (SNV) that accounts for several breast cancer riskâassociated loci. Our work highlights the importance of considering the combinatorial activity of regulatory elements as a single unit to delineate the impact of noncoding genetic alterations on single genes in cancer. RNA-Seq was performed in HCC1419 cells heterozygous for the functional SNV, rs9383590, to determine which genes displayed an allelic imbalance within a 1MB window.
Project description:Sustained expression of the estrogen receptor-α (ESR1) drives two-thirds of breast cancer and defines the ESR1-positive subtype. ESR1 engages enhancers upon estrogen stimulation to establish an oncogenic expression program1. Somatic copy number alterations involving the ESR1 gene occur in approximately 1 % of ESR1-positive breast cancers2–5, suggesting that other mechanisms underlie the persistent expression of ESR1. We report significant enrichment of somatic mutations within the set of regulatory elements (SRE) regulating ESR1 in 7% of ESR1-positive breast cancers. These mutations regulate ESR1 expression by modulating transcription factor binding to the DNA. The SRE includes a recurrently mutated enhancer whose activity is also affected by rs9383590, a functional inherited single-nucleotide variant (SNV) that accounts for several breast cancer risk–associated loci. Our work highlights the importance of considering the combinatorial activity of regulatory elements as a single unit to delineate the impact of noncoding genetic alterations on single genes in cancer.
Project description:Thousands of noncoding somatic Single Nucleotide Variants (SNVs) of unknown function are reported in tumors. Partitioning the genome according to cistromes, reveals the enrichment of somatic SNVs in prostate tumors as opposed to adjacent normal tissue cistromes of master transcription regulators, including AR, FOXA1 and HOXB13. This parallels enrichment of prostate cancer genetic predispositions over these transcription regulators’ tumor cistromes, exemplified at the 8q24 locus harboring both risk-variants and somatic SNVs in cis-regulatory elements, upregulating MYC expression and altering the binding of transcription regulators to DNA. However, Massively-Parallel Reporter Assays reveal that few SNVs can alter the transactivation potential of individual CREs. Instead, SNVs accumulate, similarly to inherited riskvariants, in cistromes of master transcription regulators required for prostate cancer development. Significance Difficulties in inferring the biological significance of noncoding mutations have limited their inclusion in precision genomics medicine pipelines. Most attempts to delineate a role for noncoding mutations relied on detecting evidence for positive selection within individual CREs, such as reported for the TERT gene promoter. By considering the enrichment of noncoding mutations in cistromes as opposed to individual CREs, we reveal their specificity towards master transcription regulators that promote prostate cancer development, a feature shared with inherited risk-variants. Overall, our work provides a blueprint for the functional interpretation of noncoding mutations in genomic tests relying on defining cis-regulatory units according to cistrome-partitioning to identify cancer driver transcription regulators.
Project description:At least six histone H1 variants exist in mammalian somatic cells that bind to the linker DNA and stabilize the nucleosome particle contributing to higher order chromatin compaction. In addition, H1 seems to be involved in the active regulation of gene expression. It is not well known whether the different variants have specific roles, are distributed differentially along the genome, or regulate specific promoters. By taking advantage of specific antibodies to H1 variants and HA-tagged recombinant H1 variants expressed in a breast cancer-derived cell line, we have investigated the distribution of the different somatic H1 variants (H1.2 to H1.5, H1.0 and H1X) in particular promoters and genome-wide. Genome-wide analysis of H1.0, H1.2, H1.4, H1X and H3
Project description:At least six histone H1 variants exist in mammalian somatic cells that bind to the linker DNA and stabilize the nucleosome particle contributing to higher order chromatin compaction. In addition, H1 seems to be involved in the active regulation of gene expression. It is not well known whether the different variants have specific roles, are distributed differentially along the genome, or regulate specific promoters. By taking advantage of specific antibodies to H1 variants and HA-tagged recombinant H1 variants expressed in a breast cancer-derived cell line, we have investigated the distribution of the different somatic H1 variants (H1.2 to H1.5, H1.0 and H1X) in particular promoters and genome-wide.
Project description:Objective: To investigate transplantation of rat Schwann cells or human iPSC-derived neural crest cells and derivatives into models of acquired and inherited peripheral myelin damage. Methods: Primary cultured rat Schwann cells labeled with a fluorescent protein for monitoring at various times after transplantation. Human induced pluripotent stem cells (iPSCs) were differentiated into neural crest stem cells (NCSC), and subsequently toward a Schwann cell lineage via two different protocols. Protocol 1 = treated with MesenPRO with Heregulin. Protocol 2 = coculture with iPSC-derived Motor Neurons. Cell types were characterized using flow cytometry, immunocytochemistry and transcriptomics. Rat Schwann cells and human iPSC-derivatives were transplanted into (i) nude rats pretreated with lysolecithin to induce demyelination or (ii) a transgenic rat model of dysmyelination due to PMP22 overexpression. Results: Rat Schwann cells transplanted into sciatic nerves with either toxic demyelination or genetic dysmyelination engrafted successfully, and migrated longitudinally for relatively long distances, with more limited axial migration. Transplanted Schwann cells engaged existing axons and displaced dysfunctional Schwann cells to form normal appearing myelin. Human iPSC-derived neural crest stem cells and their derivatives shared similar engraftment and migration characteristics to rat Schwann cells after transplantation, but did not further differentiate into Schwann cells or form myelin. Interpretation: These results indicate that cultured Schwann cells surgically delivered to peripheral nerve can engraft and form myelin in either acquired or inherited myelin injury, as proof of concept for pursuing cell therapy for diseases of peripheral nerve. However, lack of reliable technology for generating human iPSC-derived Schwann cells for transplantation therapy remains a barrier in the field.
Project description:At least six histone H1 variants exist in mammalian somatic cells that bind to the linker DNA and stabilize the nucleosome particle contributing to higher order chromatin compaction. In addition, H1 seems to be involved in the active regulation of gene expression. It is not well known whether the different variants have specific roles, are distributed differentially along the genome, or regulate specific promoters. By taking advantage of specific antibodies to H1 variants and HA-tagged recombinant H1 variants expressed in a breast cancer-derived cell line, we have investigated the distribution of the different somatic H1 variants (H1.2 to H1.5, H1.0 and H1X) in particular promoters and genome-wide. Analysis of H1 (H1.0, H1.2, H1.3, H1.4, H1.5 and H1X) and H3 abundance in promoter regions
Project description:Background: Causative genes are mostly unknown for the mismatch repair-proficient category of familial colorectal cancers designated as FCCTX. Recent evidence suggests shared susceptibility factors between colorectal and hematological malignancies. Study design: We investigated 28 FCCTX families by exome sequencing, supplemented with whole genome sequencing, RNA-sequencing, and tumor studies to identify the predisposing genes. Guided by the findings, germline and somatic exomes of ~400 patients with acute leukemia, myelodysplastic syndrome, and myeloma were subsequently examined. Results: A family with hematological and solid malignancies revealed a truncating variant in the DEAH-box RNA helicase gene DHX40 co-segregating with disease in seven family members. Neoplastic tissues revealed no apparent “second hit”, implying a haploinsufficiency model of tumorigenesis. DHX40 siRNA-treated cell lines exhibited a 13% increase in aberrantly spliced transcripts vs. GAPDH-siRNA or non-target siRNA-treated cells. Two additional families showed truncating germline variants in the TDRD9 and TDRD5 genes encoding Tudor domain-containing RNA-binding proteins. In the hospital-based hematological series, 18% of germline and 28% of somatic exomes revealed possibly pathogenic DEAD/H box gene variants, including somatic variants of DHX40 in four. Conclusions: This study identifies DHX40, TDRD9, and TDRD5 as novel candidate genes for FCCTX predisposition. In the family segregating the truncating DHX40 variant, two carriers had hematological neoplasia, suggesting possible analogy to DDX41, a DEAD-box RNA helicase gene previously linked to myeloid malignancies. Our findings emphasize aberrant RNA metabolism behind FCCTX and hematological neoplasia.