Dual engagement of 14-3-3 proteins controls signal relay from ASK2 to the ASK1 signalosome.
Faithful and efficient transmission of biological signals through mitogen-activated protein kinase (MAPK) pathways requires engagement of highly regulated cellular machinery in response to diverse environmental cues. Here, we report a novel mechanism controlling signal relay between two MAP3Ks, apoptosis signal-regulating kinase (ASK) 1 and ASK2. We show that ASK2 specifically interacts with 14-3-3 proteins through phosphorylated S964. Although a 14-3-3-binding defective mutant of ASK1 (S967A) has no effect on the ASK2/14-3-3 interaction, both overexpression of the analogous ASK2 (S964A) mutant and knockdown of ASK2 dramatically reduced the amount of ASK1 complexed with 14-3-3. These data suggest a dominant role of ASK2 in 14-3-3 control of ASK1 function. Indeed, ASK2 S964A-induced dissociation of 14-3-3 from ASK1 correlated with enhanced phosphorylation of ASK1 at T838 and increased c-Jun N-terminal kinase phosphorylation, the two biological readouts of ASK1 activation. Our results suggest a model in which upstream signals couple ASK2 S964 phosphorylation to the ASK1 signalosome through dual engagement of 14-3-3.
Cockrell
L M
LM
Program in Molecular and Systems Pharmacology of the Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, GA 30322, USA.
Puckett
M C
MC
Goldman
E H
EH
Khuri
F R
FR
Fu
H
H
D048948:14-3-3 Proteins / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D006367:HeLa Cells; D006801:Humans; D048848:MAP Kinase Kinase Kinase 5 / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D015398:Signal Transduction; D013379:Substrate Specificity
D048948:14-3-3 Proteins; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases; C116394:MAP kinase kinase kinase 6