Project description:In mammalian cells, the catabolic activity of the dNTP triphosphohydrolase SAMHD1 sets the balance and the concentrations of the four dNTPs. Deficiency of SAMHD1 leads to unequally increased pools and marked dNTP imbalance. Although it is documented that imbalanced dNTP pool expansion increases mutation frequency in cancer cells, it is not known if the SAMHD1-induced dNTP imbalance favors accumulation of somatic mutations in non-transformed cells. Here we have investigated how fibroblasts isolated from Aicardi Goutières Syndrome (AGS) patients with mutated SAMHD1 react to the constitutive pool imbalance characterized by a huge dGTP pool. We focused on the effects on dNTP pools, cell-cycle progression, dynamics and fidelity of DNA replication, efficiency of UV-induced DNA repair. AGS fibroblasts entered senescence prematurely or upregulated genes involved in G1/S transition and DNA replication. The normally growing AGS cells exhibited unchanged DNA replication dynamics and, when quiescent, faster rate of excision repair of UV-induced DNA damages than wildtype fibroblasts. To investigate if the lack of SAMHD1 affects DNA replication fidelity we compared de novo mutations in AGS and WT cells by exome next generation sequencing. Somatic variant analysis indicated a mutator phenotype suggesting that SAMHD1 is a caretaker gene whose deficiency is per se mutagenic promoting genome instability in non-transformed cells.
Project description:The aim of this study was to compare RNA-seq profiles of wild-type fibroblasts and patient-derived fibroblasts carrying pathogenic EPG5 mutations. Using an adjusted p-value threshold of < 0.05, we identified 5,303 differentially expressed transcripts in patient fibroblasts harboring a homozygous p.Gln336Arg missense mutation, of which 2,651 were upregulated and 2,652 were downregulated. In patient fibroblasts carrying compound heterozygous truncating mutations (p.Arg299*/p.Pro1827Ala), we identified 6,317 differentially expressed transcripts, including 3,239 upregulated and 3,078 downregulated transcripts, compared with control 1 fibroblasts.
Project description:To elucidate responses of myeloid cells to SAMHD1 deficiency in the absence of exogenous viral infection, we performed global gene expression analysis of SAMHD1 deficient macrophages.
Project description:To investigate the contribution of type-1 IFN signalling to the upregulation of IFN- stimulated genes in SAMHD1-deficient cells, we performed global gene expression analysis of SAMHD1-deficient IFNAR-/- macrophages. Peritoneal macrophages from ten SAMHD1-deficient IFNAR-/- and six SAMHD1-deficient controls were FACS sorted. RNA was subjected to next generation mRNA sequencing.
Project description:We identified novel recurrent genetic lesions in T-PLL affecting genes involved in JAK/STAT signaling (PTPRC), epigenetic regulation (PRDM2), or DNA damage repair (SAMHD1, PARP10, HERC1, HERC2). Mutations of the tumor suppressor gene SAMHD1 causing amino-acid exchanges or protein truncations as well as copy number variations in SAMHD1 were seen in 20% of cases.
Project description:We identified novel recurrent genetic lesions in T-PLL affecting genes involved in JAK/STAT signaling (PTPRC), epigenetic regulation (PRDM2), or DNA damage repair (SAMHD1, PARP10, HERC1, HERC2). Mutations of the tumor suppressor gene SAMHD1 causing amino-acid exchanges or protein truncations as well as copy number variations in SAMHD1 were seen in 20% of cases.
Project description:To elucidate responses of myeloid cells to SAMHD1 deficiency in the absence of exogenous viral infection, we performed global gene expression analysis of SAMHD1 deficient macrophages. Peritoneal macrophages from nine mutants and nine controls were FACS sorted. Cells from three animals were pooled to yield three poolls per group. RNA from these pools was subjected to next generation mRNA sequencing
Project description:To elucidate responses of myeloid cells to SAMHD1 deficiency in the absence of exogenous viral infection, we performed global gene expression analysis of SAMHD1 deficient macrophages.
Project description:To investigate the signalling pathways affected by SAMHD1 depletion, whole transciptome profiling was performed in WT and in different clones of SAMHD1-KO breast cancer cell line (T47D cells)
Project description:To investigate the contribution of type-1 IFN signalling to the upregulation of IFN- stimulated genes in SAMHD1-deficient cells, we performed global gene expression analysis of SAMHD1-deficient IFNAR-/- macrophages.