Gene expression analysis of murine peritoneal macrophages deficient for SAMHD1 and IFNAR
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ABSTRACT: 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: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. Peritoneal macrophages from 10 mutants and 10 controls were FACS sorted. Isolated RNA was subjected to next generation mRNA sequencing.
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.
Project description:SAMHD1 restricts HIV-1 replication in dendritic and other myeloid cells. SAMHD1 has been shown to possess a dGTP-dependent dNTP triphosphatase (dNTPase) activity and is proposed to inhibit HIV-1 replication by depleting the intracellular dNTP pool. Arguing against a role for SAMHD1 dNTPase in HIV-1 restriction, the phosphorylation of SAMHD1 regulates the restriction activity toward HIV-1 without affecting its ability to decrease cellular dNTP levels. Here, we show that SAMHD1 is a phospho-regulated RNase and that the RNase function is required for HIV-1 restriction. Mutation of the SAMHD1 D137 residue in the allosteric site (SAMHD1D137N) abolishes dNTPase activity but has no effect on RNase activity. This dNTPase-defective SAMHD1D137N mutant is able to restrict HIV-1 infection to nearly the same extent as wild-type SAMHD1. SAMHD1 associates with and degrades the HIV-1 genomic RNA during the early phases of infection. SAMHD1 silencing in macrophages and CD4+ T cells from healthy donors increases HIV-1 RNA stability, thus rendering the cells permissive for HIV-1 infection. Furthermore, the phosphorylation of SAMHD1 at position T592 abolishes the RNase activity toward HIV-1 RNA, and consequently the ability of SAMHD1 to restrict HIV-1 infection, uncovering the phosphorylation of SAMHD1 T592 as a negative regulatory mechanism of RNase activity. Together, our results demonstrate that SAMHD1 is an essential RNase that prevents HIV-1 infection by directly degrading HIV-1 genomic RNA in a phosphorylation-regulated manner. The unique property of SAMHD1 that cleaves HIV-1 genomic RNA with no sequence preferences could be exploited to develop a new class of intervention for error-prone retroviruses. Ribosomal RNA-depleted total RNA profiles of mock, SAMHD1 wild type and mutants infected with HIV-1 were examined at the time of 0, 1, 3 h by Illumina Hiseq2500.
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 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:SAMHD1 restricts HIV-1 replication in dendritic and other myeloid cells. SAMHD1 has been shown to possess a dGTP-dependent dNTP triphosphatase (dNTPase) activity and is proposed to inhibit HIV-1 replication by depleting the intracellular dNTP pool. Arguing against a role for SAMHD1 dNTPase in HIV-1 restriction, the phosphorylation of SAMHD1 regulates the restriction activity toward HIV-1 without affecting its ability to decrease cellular dNTP levels. Here, we show that SAMHD1 is a phospho-regulated RNase and that the RNase function is required for HIV-1 restriction. Mutation of the SAMHD1 D137 residue in the allosteric site (SAMHD1D137N) abolishes dNTPase activity but has no effect on RNase activity. This dNTPase-defective SAMHD1D137N mutant is able to restrict HIV-1 infection to nearly the same extent as wild-type SAMHD1. SAMHD1 associates with and degrades the HIV-1 genomic RNA during the early phases of infection. SAMHD1 silencing in macrophages and CD4+ T cells from healthy donors increases HIV-1 RNA stability, thus rendering the cells permissive for HIV-1 infection. Furthermore, the phosphorylation of SAMHD1 at position T592 abolishes the RNase activity toward HIV-1 RNA, and consequently the ability of SAMHD1 to restrict HIV-1 infection, uncovering the phosphorylation of SAMHD1 T592 as a negative regulatory mechanism of RNase activity. Together, our results demonstrate that SAMHD1 is an essential RNase that prevents HIV-1 infection by directly degrading HIV-1 genomic RNA in a phosphorylation-regulated manner. The unique property of SAMHD1 that cleaves HIV-1 genomic RNA with no sequence preferences could be exploited to develop a new class of intervention for error-prone retroviruses.
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:Sterile alpha motif and HD domain-containing protein 1 (SAMHD1) has a dNTPase-independent function in promoting DNA end resection to facilitate DNA double-strand break (DSB) repair by homologous recombination (HR); however, it is not known if upstream signaling events govern this activity. Here, we show that SAMHD1 is deacetylated by the SIRT1 sirtuin deacetylase, facilitating its binding with ssDNA at DSBs, to promote DNA end resection and HR. SIRT1 complexes with and deacetylates SAMHD1 at conserved lysine 354 (K354) specifically in response to DSBs. K354 deacetylation by SIRT1 promotes DNA end resection and HR but not SAMHD1 tetramerization or dNTPase activity. Mechanistically, K354 deacetylation by SIRT1 promotes SAMHD1 recruitment to DSBs and binding to ssDNA at DSBs, which in turn facilitates CtIP ssDNA binding, leading to promotion of genome integrity. Our findings define a mechanism governing the dNTPase-independent resection function of SAMHD1 by SIRT1 deacetylation in promoting HR and genome stability.
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.