Negative regulation of mixed lineage kinase 3 by protein kinase B/AKT leads to cell survival

J Biol Chem. 2003 Feb 7;278(6):3897-902. doi: 10.1074/jbc.M211598200. Epub 2002 Nov 27.

Abstract

Mixed lineage kinase 3 (MLK3) is a mitogen-activated protein kinase kinase kinase (MAPKKK) that activates c-jun N-terminal kinase (JNK) and can induce cell death in neurons. By contrast, the activation of phosphatidylinositol 3-kinase and AKT/protein kinase B (PKB) acts to suppress neuronal apoptosis. Here, we report a functional interaction between MLK3 and AKT1/PKBalpha. Endogenous MLK3 and AKT1 interact in HepG2 cells, and this interaction is regulated by insulin. The interaction domain maps to the C-terminal half of MLK3 (amino acids 511-847), and this region also contains a putative AKT phosphorylation consensus sequence. Endogenous JNK, MKK7, and MLK3 kinase activities in HepG2 cells are significantly attenuated by insulin treatment, whereas the phosphatidylinositol 3-kinase inhibitors LY294002 and wortmannin reversed the effect. Finally, MLK3-mediated JNK activation is inhibited by AKT1. AKT phosphorylates MLK3 on serine 674 both in vitro and in vivo. Furthermore, the expression of activated AKT1 inhibits MLK3-mediated cell death in a manner dependent on serine 674 phosphorylation. Thus, these data provide the first direct link between MLK3-mediated cell death and its regulation by a cell survival signaling protein, AKT1.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Cell Line
  • Cell Survival*
  • DNA Primers
  • HeLa Cells
  • Humans
  • MAP Kinase Kinase Kinases / metabolism*
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Phosphorylation
  • Protein-Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt

Substances

  • DNA Primers
  • Proto-Oncogene Proteins
  • AKT1 protein, human
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • MAP Kinase Kinase Kinases
  • mitogen-activated protein kinase kinase kinase 11