p115 Rho GTPase activating protein interacts with MEKK1.
Mammalian MAP/ERK kinase kinase 1 (MEKK1) was identified as a mammalian homolog of Ste11p of the yeast pheromone-induced mating pathway. Like Ste11p, MEKK1 is a MAP3 kinase linked to at least two MAP kinase cascades and regulatory events that require cytoskeletal reorganization. MEKK1 is activated by molecules that impact cytoskeletal function. MEKK1-/-cells are defective in cell migration, demonstrating that it is required for cell motility. MEKK1 has a 1,200 residue N-terminal regulatory domain that interacts with a dozen identified proteins. Using part of the MEKK1 N-terminus in a yeast two-hybrid screen, we discovered a novel interaction with p115 Rho GTPase-activating protein (GAP). The p115 Rho GAP binds to MEKK1 in vitro and in intact cells. The p115 Rho GAP has selectivity for RhoA over other Rho family members. Expression of p115 Rho GAP reduces MEKK1-induced signaling to AP-1. The reduced activation of AP-1 is dependent on the association of MEKK1 with p115 Rho GAP, because deletion of the Rho GAP SH3 domain, which abrogates their interaction, restores the stimulatory effect of MEKK1 on AP-1 activity. Here we have identified an MEKK1 binding partner that offers a connection between this protein kinase and the machinery regulating cytoskeletal reorganization.
Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041, USA.
Lori B
LB
Christerson
Ewen
E
Gallagher
Colleen A
CA
Vanderbilt
Angelique W
AW
Whitehurst
Clark
C
Wells
Roxana
R
Kazempour
Paul C
PC
Sternweis
Melanie H
MH
Cobb
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002645:Chickens; D018076:DNA, Complementary / Q000302:isolation & purification*; D004285:Dogs; D020690:GTPase-Activating Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D048728:MAP Kinase Kinase Kinase 1; D051379:Mice; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D014018:Tissue Distribution; D020798:Two-Hybrid System Techniques
D018076:DNA, Complementary; D020690:GTPase-Activating Proteins; C085379:rho GTPase-activating protein; D017346:Protein Serine-Threonine Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; C482578:Map3k1 protein, mouse