title: PIM1 phosphorylates and negatively regulates ASK1-mediated apoptosis.
abstract: The serine/threonine kinase, PIM1, is involved in promoting cell survival in part by phosphorylation and inhibition of proapoptotic proteins. Apoptosis signaling kinase 1 (ASK1), a mitogen-activated protein kinase kinase kinase, is involved in the so-called stress-activated pathways that contribute to apoptotic cell death. Here we show that PIM1 phosphorylates ASK1 specifically on serine residue 83 (Ser83) both in vitro and in vivo and that PIM1 binds to ASK1 in cells by co-immunoprecipitation. Using H1299 cells, our results further demonstrate that PIM1 phosphorylation of ASK1 decreases its kinase activity induced by oxidative stress. PIM1 phosphorylation of ASK1 on Ser83 inhibited ASK1-mediated c-Jun N-terminal kinase phosphorylation as well as p38 kinase phosphorylation. Under H(2)O(2)-induced stress conditions that normally lead to apoptosis, these phosphorylation events were associated with inhibition of caspase-3 activation and resulted in reduced cell death. Moreover, knockdown of PIM1 in H1299 cells decreased phosphorylation of endogenous Ser83 of ASK1 and was associated with a decrease in cell viability after H(2)O(2) treatment. Taken together, these data reveal a novel mechanism by which PIM1 promotes cell survival that involves negative regulation of the stress-activated kinase, ASK1.
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, WA 99164-7520, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Gu
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: R
authors.initials: R
authors.lastname: Reeves
authors.forename: N S
authors.initials: NS
authors.lastname: Magnuson
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000187:drug effects / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D045744:Cell Line, Tumor; D006801:Humans; D048848:MAP Kinase Kinase Kinase 5 / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology; D010766:Phosphorylation; D011485:Protein Binding; D017510:Protein Folding; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D017346:Protein Serine-Threonine Kinases; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases; C482858:MAP3K5 protein, human