Abstract:a and IFN-
is described. B7 was FACS sorted from a cellular pool, which was obtained from the parental cell line 2C4, after several rounds of mutagenesis. The partial responsiveness to IFN was observed both in terms of expression of cell surface markers (CD2, class I and II HLAs) and mRNA expression of IFN-stimulated genes (9-27; 6-16; 2'-5' OAS; GBP and HLA-DRa). A genetic cross with the U4 mutant (JAK1-, a member of the Janus family of nonreceptor tyrosine kinase) did not restore full IFN-responsi… Show more
“…When appropriate, cells were incubated with the specific IPK for 15-60 min prior to and throughout VV infection. EMSA was carried out essentially as described (38). Whole cell extracts were prepared by a modification of the method already described (39).…”
Vaccinia virus (VV) triggers a mitogenic signal at an early stage of infection. VV-induced proto-oncogene c-fos mRNA with kinetics paralleling that stimulated by serum. The VV virokine, or vaccinia virus growth factor (VGF), was not crucial for c-fos induction because it was observed upon infection with the virokine-minus mutant VV (VGF ؊ ). Furthermore, c-fos expression did not require infectious virus particles, as it occurred even with UV-inactivated VV and was equally induced by the different multiplicities of infection, i.e. 1.0, 5.0, and 25.0. c-fos expression was preceded by VV-induced DNA binding activity and was mediated via the cis-acting elements serum response element (SRE), activating protein-1 (AP-1), and cAMP-response element (CRE). VV activated the protein kinases p42MAPK/ERK2 and p44MAPK/ERK1 and the transcription factor ATF1 in a time-dependent manner with kinetics that paralleled those of VV-stimulated DNAprotein complex formation. The mitogenic signal transmission pathways leading to c-fos activation upon VV infection were apparently mediated by the protein kinases MEK, ERK, and PKA. This assumption was based on the findings that: 1) c-fos transcript was down-regulated; 2) the SRE, AP-1, and CRE binding activities were significantly reduced; and 3) the activation of p42MAPK/ERK2, p44MAPK/ERK1, and ATF1 were drastically affected when the viral infections were carried out in the presence of specific protein kinase inhibitor. Moreover, the mutant VV (VGF ؊ ) was also able to activate ERK1/2. It is noteworthy that virus multiplication was equally affected by the same kinase inhibitors. Taken together, our data provide evidence that the early mitogenic signal triggered upon VV infection relies upon the activation of the protein kinases MEK, ERK, and PKA, which are needed for both signal transduction and virus multiplication.
“…When appropriate, cells were incubated with the specific IPK for 15-60 min prior to and throughout VV infection. EMSA was carried out essentially as described (38). Whole cell extracts were prepared by a modification of the method already described (39).…”
Vaccinia virus (VV) triggers a mitogenic signal at an early stage of infection. VV-induced proto-oncogene c-fos mRNA with kinetics paralleling that stimulated by serum. The VV virokine, or vaccinia virus growth factor (VGF), was not crucial for c-fos induction because it was observed upon infection with the virokine-minus mutant VV (VGF ؊ ). Furthermore, c-fos expression did not require infectious virus particles, as it occurred even with UV-inactivated VV and was equally induced by the different multiplicities of infection, i.e. 1.0, 5.0, and 25.0. c-fos expression was preceded by VV-induced DNA binding activity and was mediated via the cis-acting elements serum response element (SRE), activating protein-1 (AP-1), and cAMP-response element (CRE). VV activated the protein kinases p42MAPK/ERK2 and p44MAPK/ERK1 and the transcription factor ATF1 in a time-dependent manner with kinetics that paralleled those of VV-stimulated DNAprotein complex formation. The mitogenic signal transmission pathways leading to c-fos activation upon VV infection were apparently mediated by the protein kinases MEK, ERK, and PKA. This assumption was based on the findings that: 1) c-fos transcript was down-regulated; 2) the SRE, AP-1, and CRE binding activities were significantly reduced; and 3) the activation of p42MAPK/ERK2, p44MAPK/ERK1, and ATF1 were drastically affected when the viral infections were carried out in the presence of specific protein kinase inhibitor. Moreover, the mutant VV (VGF ؊ ) was also able to activate ERK1/2. It is noteworthy that virus multiplication was equally affected by the same kinase inhibitors. Taken together, our data provide evidence that the early mitogenic signal triggered upon VV infection relies upon the activation of the protein kinases MEK, ERK, and PKA, which are needed for both signal transduction and virus multiplication.
“…A31 cells were cultured and starved as above and then treated with IFN for the indicated times, or were incubated with PD98059 (50µM) for 30 min prior to and throughout IFN treatment. EMSA was carried out essentially as described (42). Nuclear cell extracts were prepared as described elsewhere (43).…”
Interferons (IFNs) are multifunctional cytokines that after binding to the cell surface receptor induce the expression of a large number of genes, which in turn, mediate many biological processes including host defense, cell growth control, signaling, and metabolism. Here we show that IFN-alpha activates the mitogen-activated protein kinases (MAPK) ERK1/2 and the transcription factor CREB/ATF-1, which lead to the alpha-enolase (alpha-ENO) gene expression in fibroblasts. Alpha-ENO mRNA accumulation was apparent 6 h post-IFN stimulation and required both de novo protein synthesis and active gene transcription, which is typical of a secondary response gene. Alpha-ENO expression does not appear to be restricted to fibroblasts, since it was equally verified in peripheral blood mononuclear cells (PBMC). Furthermore, IFN-alpha stimulates the expression of the primary response genes c-fos and egr-1, which was followed by an increase in DNA binding activity of c-FOS and EGR-1 proteins, as verified by shift assays using the cis-acting elements AP-1 and EGR-1 localized at the alpha-ENO promoter. Finally, we also demonstrated that IFN treatment of PBMC cause an increase in both, alpha-ENO expression on the cell surface and plasmin generation followed addition of exogenous plasminogen.
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