Targeted disruption of the mouse alpha A-crystallin gene induces cataract and cytoplasmic inclusion bodies containing the small heat shock protein alpha B-crystallin

Proc Natl Acad Sci U S A. 1997 Feb 4;94(3):884-9. doi: 10.1073/pnas.94.3.884.


alpha A-crystallin (alpha A) and alpha B-crystallin (alpha B) are among the predominant proteins of the vertebrate eye lens. In vitro, the alpha-crystallins, which are isolated together as a high molecular mass aggregate, exhibit a number of properties, the most interesting of which is their ability to function as molecular chaperones for other proteins. Here we begin to examine the in vivo functions of alpha-crystallin by generating mice with a targeted disruption of the alpha A gene. Mice that are homozygous for the disrupted allele produce no detectable alpha A in their lenses, based on protein gel electrophoresis and immunoblot analysis. Initially, the alpha A-deficient lenses appear structurally normal, but they are smaller than the lenses of wild-type littermates. alpha A-/- lenses develop an opacification that starts in the nucleus and progresses to a general opacification with age. Light and transmission electron microscopy reveal the presence of dense inclusion bodies in the central lens fiber cells. The inclusions react strongly with antibodies to alpha B but not significantly with antibodies to beta- or gamma-crystallins. In addition, immunoblot analyses demonstrate that a significant portion of the alpha B in alpha A-/- lenses shifts into the insoluble fraction. These studies suggest that alpha A is essential for maintaining lens transparency, possibly by ensuring that alpha B or proteins closely associated with this small heat shock protein remain soluble.

MeSH terms

  • Animals
  • Base Sequence
  • Cataract / genetics*
  • Crystallins / analysis*
  • Crystallins / genetics*
  • Crystallins / physiology
  • Gene Expression
  • Heat-Shock Proteins / analysis*
  • Inclusion Bodies / chemistry*
  • Lens, Crystalline / chemistry*
  • Lens, Crystalline / growth & development
  • Mice
  • Mice, Knockout
  • Molecular Sequence Data


  • Crystallins
  • Heat-Shock Proteins