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Human alphaA- and alphaB-crystallins bind to Bax and Bcl-X(S) to sequester their translocation during staurosporine-induced apoptosis.

AlphaA- and alphaB-crystallins are distinct antiapoptotic regulators. Regarding the antiapoptotic mechanisms, we have recently demonstrated that alphaB-crystallin interacts with the procaspase-3 and partially processed procaspase-3 to repress caspase-3 activation. Here, we demonstrate that human alphaA- and alphaB-crystallins prevent staurosporine-induced apoptosis through interactions with members of the Bcl-2 family. Using GST pulldown assays and coimmunoprecipitations, we demonstrated that alpha-crystallins bind to Bax and Bcl-X(S) both in vitro and in vivo. Human alphaA- and alphaB-crystallins display similar affinity to both proapoptotic regulators, and so are true with their antiapoptotic ability tested in human lens epithelial cells, human retina pigment epithelial cells (ARPE-19) and rat embryonic myocardium cells (H9c2) under treatment of staurosporine, etoposide or sorbitol. Two prominent mutants, R116C in alphaA-crystallin and R120G, in alphaB-crystallin display much weaker affinity to Bax and Bcl-X(S). Through the interaction, alpha-crystallins prevent the translocation of Bax and Bcl-X(S) from cytosol into mitochondria during staurosporine-induced apoptosis. As a result, alpha-crystallins preserve the integrity of mitochondria, restrict release of cytochrome c, repress activation of caspase-3 and block degradation of PARP. Thus, our results demonstrate a novel antiapoptotic mechanism for alpha-crystallins.

Pubmed ID: 14752512


  • Mao YW
  • Liu JP
  • Xiang H
  • Li DW


Cell death and differentiation

Publication Data

May 19, 2004

Associated Grants

  • Agency: NEI NIH HHS, Id: EY11372
  • Agency: NEI NIH HHS, Id: R29 EY011372

Mesh Terms

  • Animals
  • Apoptosis
  • Caspases
  • Cells, Cultured
  • Cytochromes c
  • Cytosol
  • Epithelial Cells
  • Etoposide
  • Genes, bcl-2
  • Humans
  • Mitochondria
  • Mutation
  • Myocytes, Cardiac
  • Protein Transport
  • Proto-Oncogene Proteins c-bcl-2
  • Rats
  • Sorbitol
  • Staurosporine
  • alpha-Crystallin A Chain
  • alpha-Crystallin B Chain
  • bcl-2-Associated X Protein
  • bcl-X Protein