Activation of mitogen-activated protein kinase kinase (MKK) 3 and MKK6 by type I interferons.
There is accumulating evidence that the p38 MAP kinase pathway plays important roles in Type I interferon (IFN) signaling, but the mechanisms regulating p38 activation during engagement of the Type I IFN receptor remain to be defined. We sought to identify the events that lead to activation of the p38 MAP kinase in response to Type I IFNs. Our data demonstrate that treatment of sensitive cell lines with IFNalpha results in activation of both MAP kinase kinase 3 (MKK3) and MAP kinase kinase 6 (MKK6). Such IFN-inducible activation of MKK3 and MKK6 is essential for downstream phosphorylation and activation of the p38 MAP kinase, as shown by studies using mouse embryonic fibroblasts (MEFs) with targeted disruption of the Mkk3 and Mkk6 genes (MKK3-/- MKK6-/-). Similarly, IFN-dependent activation of the downstream effectors of p38, MAPKAPK-2 and MAPKAPK-3, is not detectable in cells lacking Mkk3 and Mkk6, demonstrating that the function of these MAP kinase kinases is required for full activation of the p38 pathway. To define the functional relevance of MKK3/6 engagement in Type I IFN signaling, IFN-inducible gene transcription was evaluated in the MKK3/MKK6 double knock-out cells. IFNalpha- and IFNbeta-dependent transcription via either interferon-stimulated response element or IFNgamma activated site elements was defective in MKK3 -/-/MKK6 -/- MEFs in luciferase reporter assays. In addition, IFN-dependent induction of two genes known to be of importance in the generation of IFN responses, Isg15 and Irf-9, was diminished in the absence of Mkk3 and Mkk6. The effects of Mkk3 and Mkk6 on IFN-dependent transcription were unrelated to any effects on the phosphorylation and activation of STAT proteins, indicating the presence of a STAT-independent mechanism. Altogether, our findings demonstrate that MKK3 and MKK6 are rapidly activated during engagement of the Type I IFN receptor and play important roles in Type I IFN signaling and the generation of IFN responses.
Li
Yongzhong
Y
Robert H. Lurie Comprehensive Cancer Center and Division of Hematology-Oncology, Northwestern University Medical School, 710 North Fairbanks St., Chicago, Illinois 60611, USA.
Batra
Sandeep
S
Sassano
Antonella
A
Majchrzak
Beata
B
Levy
David E
DE
Gaestel
Matthias
M
Fish
Eleanor N
EN
Davis
Roger J
RJ
Platanias
Leonidas C
LC
D000818:Animals; D002478:Cells, Cultured; D016207:Cytokines / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism; D017930:Genes, Reporter; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D007370:Interferon Type I / Q000737:chemistry*; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha / Q000378:metabolism; D016899:Interferon-beta / Q000378:metabolism; D007372:Interferons / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D048371:MAP Kinase Kinase 3 / Q000378:metabolism*; D048669:MAP Kinase Kinase 6 / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000737:chemistry; D020218:Response Elements; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014443:Tyrosine / Q000737:chemistry; D014452:Ubiquitins / Q000737:chemistry; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D016207:Cytokines; D004268:DNA-Binding Proteins; C489550:G1p2 protein, mouse; C494227:IRF9 protein, human; D007370:Interferon Type I; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha; C494228:Isgf3g protein, mouse; D011994:Recombinant Proteins; D014157:Transcription Factors; D014452:Ubiquitins; D014443:Tyrosine; D012694:Serine; D016899:Interferon-beta; D007372:Interferons; D008156:Luciferases; D048051:p38 Mitogen-Activated Protein Kinases; D048371:MAP Kinase Kinase 3; D048669:MAP Kinase Kinase 6; C482531:Map2k3 protein, mouse; C482567:Map2k6 protein, mouse