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: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:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Transcriptional profiling of Homo sapiens inflammatory skin diseases (whole skin biospies): Psoriasis (Pso), vs Atopic Dermatitis (AD) vs Lichen planus (Li), vs Contact Eczema (KE), vs Healthy control (KO) In recent years, different genes and proteins have been highlighted as potential biomarkers for psoriasis, one of the most common inflammatory skin diseases worldwide. However, most of these markers are not psoriasis-specific but also found in other inflammatory disorders. We performed an unsupervised cluster analysis of gene expression profiles in 150 psoriasis patients and other inflammatory skin diseases (atopic dermatitis, lichen planus, contact eczema, and healthy controls). We identified a cluster of IL-17/TNFα-associated genes specifically expressed in psoriasis, among which IL-36γ was the most outstanding marker. In subsequent immunohistological analyses IL-36γ was confirmed to be expressed in psoriasis lesions only. IL-36γ peripheral blood serum levels were found to be closely associated with disease activity, and they decreased after anti-TNFα-treatment. Furthermore, IL-36γ immunohistochemistry was found to be a helpful marker in the histological differential diagnosis between psoriasis and eczema in diagnostically challenging cases. These features highlight IL-36γ as a valuable biomarker in psoriasis patients, both for diagnostic purposes and measurement of disease activity during the clinical course. Furthermore, IL-36γ might also provide a future drug target, due to its potential amplifier role in TNFα- and IL-17 pathways in psoriatic skin inflammation. In recent years, different genes and proteins have been highlighted as potential biomarkers for psoriasis, one of the most common inflammatory skin diseases worldwide. However, most of these markers are not psoriasis-specific but also found in other inflammatory disorders. We performed an unsupervised cluster analysis of gene expression profiles in 150 psoriasis patients and other inflammatory skin diseases (atopic dermatitis, lichen planus, contact eczema, and healthy controls). We identified a cluster of IL-17/TNFα-associated genes specifically expressed in psoriasis, among which IL-36γ was the most outstanding marker. In subsequent immunohistological analyses IL-36γ was confirmed to be expressed in psoriasis lesions only. IL-36γ peripheral blood serum levels were found to be closely associated with disease activity, and they decreased after anti-TNFα-treatment. Furthermore, IL-36γ immunohistochemistry was found to be a helpful marker in the histological differential diagnosis between psoriasis and eczema in diagnostically challenging cases. These features highlight IL-36γ as a valuable biomarker in psoriasis patients, both for diagnostic purposes and measurement of disease activity during the clinical course. Furthermore, IL-36γ might also provide a future drug target, due to its potential amplifier role in TNFα- and IL-17 pathways in psoriatic skin inflammation.