title: TRAF2-MLK3 interaction is essential for TNF-alpha-induced MLK3 activation.
abstract: Mixed lineage kinase 3 (MLK3) is a mitogen-activated protein kinase kinase kinase that is activated by tumor necrosis factor-alpha (TNF-alpha) and specifically activates c-Jun N-terminal kinase (JNK) on TNF-alpha stimulation. The mechanism by which TNF-alpha activates MLK3 is still not known. TNF receptor-associated factors (TRAFs) are adapter molecules that are recruited to cytoplasmic end of TNF receptor and mediate the downstream signaling, including activation of JNK. Here, we report that MLK3 associates with TRAF2, TRAF5 and TRAF6; however only TRAF2 can significantly induce the kinase activity of MLK3. The interaction domain of TRAF2 maps to the TRAF domain and for MLK3 to its C-terminal half (amino acids 511-847). Endogenous TRAF2 and MLK3 associate with each other in response to TNF-alpha treatment in a time-dependent manner. The association between MLK3 and TRAF2 mediates MLK3 activation and competition with the TRAF2 deletion mutant that binds to MLK3 attenuates MLK3 kinase activity in a dose-dependent manner, on TNF-alpha treatment. Furthermore the downstream target of MLK3, JNK was activated by TNF-alpha in a TRAF2-dependent manner. Hence, our data show that the direct interaction between TRAF2 and MLK3 is required for TNF-alpha-induced activation of MLK3 and its downstream target, JNK.
authors.affiliation: Department of Pharmacology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA.
authors.forename: Gautam
authors.initials: G
authors.lastname: Sondarva
authors.forename: Chanakya N
authors.initials: CN
authors.lastname: Kundu
authors.forename: Suneet
authors.initials: S
authors.lastname: Mehrotra
authors.forename: Rajakishore
authors.initials: R
authors.lastname: Mishra
authors.forename: Velusamy
authors.initials: V
authors.lastname: Rangasamy
authors.forename: Pradeep
authors.initials: P
authors.lastname: Sathyanarayana
authors.forename: Rajarshi S
authors.initials: RS
authors.lastname: Ray
authors.forename: Basabi
authors.initials: B
authors.lastname: Rana
authors.forename: Ajay
authors.initials: A
authors.lastname: Rana
mesh_terms: D000818:Animals; D020134:Catalytic Domain / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D019169:Jurkat Cells; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation / Q000502:physiology; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000502:physiology; D047992:TNF Receptor-Associated Factor 2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D048015:TNF Receptor-Associated Factor 5 / Q000378:metabolism; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism; D015533:Transcriptional Activation; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11
chemical_list: D048031:JNK Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D047992:TNF Receptor-Associated Factor 2; D048015:TNF Receptor-Associated Factor 5; D048029:TNF Receptor-Associated Factor 6; D014409:Tumor Necrosis Factor-alpha; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11