title: Actin-binding protein-280 binds the stress-activated protein kinase (SAPK) activator SEK-1 and is required for tumor necrosis factor-alpha activation of SAPK in melanoma cells.
abstract: SEK-1, a dual specificity protein kinase that serves as one of the immediate upstream activators of the stress-activated protein kinases (SAPKs), associates specifically with the actin-binding protein, ABP-280, in vitro and in situ. SEK-1 binds to the carboxyl-terminal rod segment of ABP-280, upstream of the ABP carboxyl-terminal dimerization domain. Activation of SEK-1 in situ increases the SEK-1 activity bound to ABP-280 without changing the amount of SEK-1 polypeptide bound. The influence of ABP-280 on SAPK regulation was evaluated in human melanoma cells that lack ABP-280 expression, and in stable transformants of these cells expressing wild type ABP, or an actin-binding but dimerization-deficient mutant ABP (ABPDeltaCT109). ABP-280-deficient cells show an activation of SAPK in response to most stimuli that is comparable to that seen in ABP-280-replete cells; ABP-280-deficient cells, however, fail to show the brisk tumor necrosis factor-alpha (TNF-alpha) activation of SAPK seen in ABP-replete cells and have an 80% reduction in SAPK activation by lysophosphatidic acid. Expression of the dimerization-deficient mutant ABP-280 fails to correct the defective SAPK response to lysophosphatidic acid, but essentially normalizes the TNF-alpha activation of SAPK. Thus, a lack of ABP-280 in melanoma cells causes a defect in the regulation of SAPK that is selective for TNF-alpha and is attributable to the lack of ABP-280 polypeptide itself rather than to the disordered actin cytoskeleton that results therefrom. ABP-280 participates in TNF-alpha signal transduction to SAPKs, in part through the binding of SEK-1.
authors.affiliation: Diabetes Unit and Medical Services, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 021291, USA.
authors.forename: A
authors.initials: A
authors.lastname: Marti
authors.forename: Z
authors.initials: Z
authors.lastname: Luo
authors.forename: C
authors.initials: C
authors.lastname: Cunningham
authors.forename: Y
authors.initials: Y
authors.lastname: Ohta
authors.forename: J
authors.initials: J
authors.lastname: Hartwig
authors.forename: T P
authors.initials: TP
authors.lastname: Stossel
authors.forename: J M
authors.initials: JM
authors.lastname: Kyriakis
authors.forename: J
authors.initials: J
authors.lastname: Avruch
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D003285:Contractile Proteins / Q000302:isolation & purification / Q000378:metabolism*; D019281:Dimerization; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology; D064448:Filamins; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D048670:MAP Kinase Kinase 4; D008545:Melanoma; D051379:Mice; D008840:Microfilament Proteins / Q000302:isolation & purification / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D000199:Actins; D003285:Contractile Proteins; C578661:FLNC protein, human; D064448:Filamins; D008840:Microfilament Proteins; D011993:Recombinant Fusion Proteins; D014409:Tumor Necrosis Factor-alpha; D004815:Epidermal Growth Factor; D000841:Anisomycin; D005982:Glutathione Transferase; D011494:Protein Kinases; D048670:MAP Kinase Kinase 4; C482559:MAP2K4 protein, human; C482562:Map2k4 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases