title: MEK kinase 2 and the adaptor protein Lad regulate extracellular signal-regulated kinase 5 activation by epidermal growth factor via Src.
abstract: Lad is an SH2 domain-containing adaptor protein that binds MEK kinase 2 (MEKK2), a mitogen-activated protein kinase (MAPK) kinase kinase for the extracellular signal-regulated kinase 5 (ERK5) and JNK pathways. Lad and MEKK2 are in a complex in resting cells. Antisense knockdown of Lad expression and targeted gene disruption of MEKK2 expression results in loss of epidermal growth factor (EGF) and stress stimuli-induced activation of ERK5. Activation of MEKK2 and the ERK5 pathway by EGF and stress stimuli is dependent on Src kinase activity. The Lad-binding motif is encoded within amino acids 228 to 282 in the N terminus of MEKK2, and expression of this motif blocks Lad-MEKK2 interaction, resulting in inhibition of Src-dependent activation of MEKK2 and ERK5. JNK activation by EGF is similarly inhibited by loss of Lad or MEKK2 expression and by blocking the interaction of MEKK2 and Lad. Our studies demonstrate that Src kinase activity is required for ERK5 activation in response to EGF, MEKK2 expression is required for ERK5 activation by Src, Lad and MEKK2 association is required for Src activation of ERK5, and EGF and Src stimulation of ERK5-regulated MEF2-dependent promoter activity requires a functional Lad-MEKK2 signaling complex.
authors.affiliation: Department of Pharmacology, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
authors.forename: Weiyong
authors.initials: W
authors.lastname: Sun
authors.forename: Xudong
authors.initials: X
authors.lastname: Wei
authors.forename: Kamala
authors.initials: K
authors.lastname: Kesavan
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Garrington
authors.forename: Ruihua
authors.initials: R
authors.lastname: Fan
authors.forename: Junjie
authors.initials: J
authors.lastname: Mei
authors.forename: Steven M
authors.initials: SM
authors.lastname: Anderson
authors.forename: Erwin W
authors.initials: EW
authors.lastname: Gelfand
authors.forename: Gary L
authors.initials: GL
authors.lastname: Johnson
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D048730:MAP Kinase Kinase Kinase 2; D020930:MAP Kinase Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances; D051379:Mice; D008907:Mink; D048054:Mitogen-Activated Protein Kinase 7; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009994:Osmolar Concentration; D018384:Oxidative Stress / Q000502:physiology; D011485:Protein Binding / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D014162:Transfection; D020798:Two-Hybrid System Techniques; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D046911:Macromolecular Substances; C402726:Sh2d2a protein, mouse; D004815:Epidermal Growth Factor; D019061:src-Family Kinases; D048054:Mitogen-Activated Protein Kinase 7; D020928:Mitogen-Activated Protein Kinases; D048730:MAP Kinase Kinase Kinase 2; D020930:MAP Kinase Kinase Kinases; C482618:MAP3K2 protein, human; C482619:Map3k2 protein, mouse