Transactivation by the p65 subunit of NF-kappaB in response to interleukin-1 (IL-1) involves MyD88, IL-1 receptor-associated kinase 1, TRAF-6, and Rac1.
We have examined the involvement of components of the interleukin-1 (IL-1) signaling pathway in the transactivation of gene expression by the p65 subunit of NF-kappaB. Transient transfection of cells with plasmids encoding wild-type MyD88, IL-1 receptor-associated kinase 1 (IRAK-1), and TRAF-6 drove p65-mediated transactivation. In addition, dominant negative forms of MyD88, IRAK-1, and TRAF-6 inhibited the IL-1-induced response. In cells lacking MyD88 or IRAK-1, no effect of IL-1 was observed. Together, these results indicate that MyD88, IRAK-1, and TRAF-6 are important downstream regulators of IL-1-mediated p65 transactivation. We have previously shown that the low-molecular-weight G protein Rac1 is involved in this response. Constitutively active RacV12-mediated transactivation was not inhibited by dominant negative MyD88, while dominant negative RacN17 inhibited the MyD88-driven response, placing Rac1 downstream of MyD88 on this pathway. Dominant negative RacN17 inhibited wild-type IRAK-1- and TRAF-6-induced transactivation, and in turn, dominant negative IRAK-1 and TRAF-6 inhibited the RacV12-driven response, suggesting a mutual codependence of Rac1, IRAK-1, and TRAF-6 in regulating this pathway. Finally, Rac1 was found to associate with the receptor complex via interactions with both MyD88 and the IL-1 receptor accessory protein. A pathway emanating from MyD88 and involving IRAK-1, TRAF-6, and Rac1 is therefore involved in transactivation of gene expression by the p65 subunit of NF-kappaB in response to IL-1.
Jefferies
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Department of Biochemistry and Biotechnology Institute, Trinity College, Dublin 2, Ireland. jefferca@tcd.ie
Bowie
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Brady
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Cooke
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Li
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O'Neill
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LA
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism* / Q000494:pharmacology; D053577:Interleukin-1 Receptor Accessory Protein; D053592:Interleukin-1 Receptor-Associated Kinases; D051379:Mice; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1 / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D048029:TNF Receptor-Associated Factor 6; D051996:Transcription Factor RelA; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; C507765:IL1RAP protein, human; C507767:Il1rap protein, mouse; D007375:Interleukin-1; D053577:Interleukin-1 Receptor Accessory Protein; C507779:MYD88 protein, human; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D011506:Proteins; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1; D048029:TNF Receptor-Associated Factor 6; D051996:Transcription Factor RelA; D011494:Protein Kinases; D053592:Interleukin-1 Receptor-Associated Kinases; D020830:rac1 GTP-Binding Protein