Vinblastine-induced phosphorylation of Bcl-2 and Bcl-XL is mediated by JNK and occurs in parallel with inactivation of the Raf-1/MEK/ERK cascade

J Biol Chem. 2000 Sep 29;275(39):29980-5. doi: 10.1074/jbc.M003776200.


Microtubule-damaging agents arrest cells at G(2)/M and induce apoptosis in association with phosphorylation of the anti-apoptotic proteins Bcl-2 and Bcl-X(L). Because microtubule inhibitors activate JNK, we sought to determine whether JNK was responsible for Bcl-2/Bcl-X(L) phosphorylation in KB-3 cells treated with vinblastine. Two major endogenous forms of JNK, p46(JNK1) and p54(JNK2), were present in KB-3 cells, and both isoforms were activated by vinblastine as determined by Mono Q chromatography. We used antisense oligonucleotides (AS) to specifically inhibit their expression. A combination of AS-JNK1 with AS-JNK2 inhibited by 80% vinblastine-induced phosphorylation of two known JNK substrates, c-Jun and ATF-2. In addition, AS-JNK1/2 inhibited vinblastine-induced phosphorylation of Bcl-2 by 85% and that of Bcl-X(L) by 65%. Stable expression of the JNK scaffold protein JIP-1 blocked vinblastine-induced phosphorylation of c-Jun and ATF-2, but did not affect Bcl-2/Bcl-X(L) phosphorylation, confirming a bifurcation in JNK signaling involving both nuclear and non-nuclear substrates. Vinblastine-induced phosphorylation of Raf-1 was unaffected by AS-JNK1/2 and was associated with loss of activity for MEK substrate in vitro and inactivation of ERK in vivo. These results provide evidence for a direct role of the JNK pathway in apoptotic regulation through Bcl-2/Bcl-X(L) phosphorylation.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing*
  • Carrier Proteins / metabolism
  • Enzyme Activation
  • Humans
  • Isoenzymes / metabolism
  • MAP Kinase Signaling System
  • Mitogen-Activated Protein Kinase 8
  • Mitogen-Activated Protein Kinase 9
  • Mitogen-Activated Protein Kinase Kinases / metabolism*
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism*
  • Oligonucleotides, Antisense / pharmacology
  • Phosphorylation
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Proto-Oncogene Proteins c-raf / metabolism*
  • Tumor Cells, Cultured
  • Vinblastine / pharmacology*
  • bcl-X Protein


  • Adaptor Proteins, Signal Transducing
  • BCL2L1 protein, human
  • Carrier Proteins
  • Isoenzymes
  • MAPK8IP1 protein, human
  • Oligonucleotides, Antisense
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-X Protein
  • Vinblastine
  • Mitogen-Activated Protein Kinase 9
  • Proto-Oncogene Proteins c-raf
  • Mitogen-Activated Protein Kinase 8
  • Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinase Kinases