Unknown,Transcriptomics,Genomics,Proteomics

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Regulating type 1 IFN effects in CD8 T cells during viral infections: changing STAT4 and STAT1 expression for function

ABSTRACT: Type 1 IFNs can conditionally activate all of the signal transducers and activators of transcription molecules (STATs), including STAT4. The best-characterized signaling pathways use STAT1, however, and type 1 IFN inhibition of cell proliferation is STAT1 dependent. We report that type 1 IFNs can basally stimulate STAT1- and STAT4- dependent effects in CD8 T cells, but that CD8 T cells responding to infections of mice with lymphocytic choriomenigitis virus have elevated STAT4 and lower STAT1 expression with significant consequences for modifying the effects of type 1 IFN exposure. The phenotype was associated with preferential type 1 IFN activation of STAT4 as compared to STAT1. Stimulation through the TCR induced elevated STAT4 expression, and STAT4 was required for peak expansion of antigen-specific CD8 T cells, low STAT1 levels, and resistance to type 1 IFN-mediated inhibition of proliferation. Thus, a mechanism is discovered for regulating the consequences of type 1 IFN exposure in CD8 T cells, with STAT4 acting as a key molecule in driving optimal antigen-specific responses and overcoming STAT1-dependent inhibition of proliferation. CD8 T cells were purified from uninfected WT, STAT1-deficient and STAT4-deficient mice or from D8 LCMV-infected WT mice and either control treated or treated with 1x104 U mouse IFNalpha for 90 minutes.

ORGANISM(S): Mus musculus

SUBMITTER: M. Pilar Gil

PROVIDER: E-GEOD-40666 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Compared to primary human monocytes in whole blood cultures, few B cells activated STAT1 in response to stimulation of 2000 IU/ml IFN-beta for 45 minutes. Because activation of STAT1 leads to apoptosis induction, we tested the hypothesis that less pro-apoptotic genes are induced in B cells as compared to monocytes. Manuscript titled: Major differences in the responses of primary human leukocyte subsets to IFN-beta. Abstract: Treatment of cell lines with type I IFNs activates the formation of ISGF3 (STAT1/STAT2/ IRF9), which induces the expression of many genes. To study this response in primary cells, we treated fresh human blood with IFN-beta and used flow cytometry to analyze phosphorylated STATs1, 3 and 5 in CD4+ and CD8+ T cells, B cells, and monocytes. The activation of STAT1 was remarkably different among these leukocyte subsets. In contrast to monocytes, CD4+ and CD8+ T cells, few B cells activated STAT1 in response to IFN-beta, a finding that could not be explained by decreased levels of IFNAR2 or STAT1 or enhanced levels of SOCS1 or relevant protein tyrosine phosphatases in B cells. Micro-array and real-time PCR analyses revealed the induction of STAT1-dependent pro-apoptotic mRNAs in monocytes but not in B cells. These data show that ISGF3 or STAT1 homodimers are not the main activators of gene expression in primary B cells of healthy humans. Notably, in B cells and especially in CD4+ T cells, IFN-beta activated STAT5 in addition to STAT3, with biological effects often opposite from those driven by activated STAT1. These data help to explain why IFN-beta increases the survival of primary human B cells and CD4+ T cells, but enhances the apoptosis of monocytes, and also to understand how leukocyte subsets are differentially affected by endogenous type I IFNs during viral or bacterial infections, and by type I IFN treatment of patients with multiple sclerosis, hepatitis or cancer. Undiluted whole blood of 2 healthy individuals (HI) was used, and either stimulated with IFN-beta or left untreated (control) for 3 hrs. After 3 hrs, both B cells and monocytes were isolated from whole blood of the first healthy individual, and only B cells were isolated from whole blood of the second healthy individual.