MEKK1 interacts with alpha-actinin and localizes to stress fibers and focal adhesions.
Mitogen-activated protein (MAP) kinases orchestrate the effects of many extracellular stimuli on cells. The serine/threonine protein kinase MEKK1 is an upstream activator of the MAP kinases c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK), extracellular signal-regulated kinase (ERK), and p38 as well as NF-kappa B. In a yeast two-hybrid interaction screen to identify proteins that bind to an N-terminal fragment of MEKK1 (amino acids 1-719), the actin-crosslinking protein alpha-actinin was identified as a MEKK1-binding protein. Over-expressed MEKK1 co-immunoprecipitated with alpha-actinin in cell lysates. Both endogenous and over-expressed MEKK1 colocalized with alpha-actinin along actin stress fibers and at focal adhesions. Residues 221-559 of MEKK1 bound to purified alpha-actinin in vitro, indicating that the interaction is direct, and this fragment localized to actin filaments in cells. MEKK1 kinase activity was not required for association with actin filaments, because a catalytically inactive mutant of MEKK1 (MEKK1 D1369A) localized to stress fibers. These results provide strong evidence for the interaction between MEKK1 and alpha-actinin. Thus, restriction of the kinase to the actin cytoskeleton may serve to regulate its specificity towards downstream targets.
Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235, USA.
L B
LB
Christerson
C A
CA
Vanderbilt
M H
MH
Cobb
D016475:3T3 Cells; D000185:Actinin / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology*; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D048728:MAP Kinase Kinase Kinase 1; D051379:Mice; D051419:Paxillin; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics
D000199:Actins; D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; C496061:PXN protein, human; D051419:Paxillin; D010446:Peptide Fragments; D010750:Phosphoproteins; D016271:Proto-Oncogene Proteins c-myc; C496062:Pxn protein, mouse; D011993:Recombinant Fusion Proteins; D000185:Actinin; D017346:Protein Serine-Threonine Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; C482578:Map3k1 protein, mouse