A role for γs-crystallin in the organization of actin and fiber cell maturation in the mouse lens

Jianguo Fan, Lijin Dong, Sanghamitra Mishra, Yingwei Chen, Paul G FitzGerald, Graeme Wistow

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

γS-crystallin (γS) is a highly conserved component of the eye lens. To gain insights into the functional role(s) of this protein, the mouse gene (Crygs) was deleted. Although mutations in γS can cause severe cataracts, loss of function of γS in knockout (KO) mice produced no obvious lens opacity, but was associated with focusing defects. Electron microscopy showed no major differences in lens cell organization, suggesting that the optical defects are primarily cytoplasmic in origin. KO lenses were also grossly normal by light microscopy but showed evidence of incomplete clearance of cellular organelles in maturing fiber cells. Phalloidin labeling showed an unusual distribution of F-actin in a band of mature fiber cells in KO lenses, suggesting a defect in the organization or processing of the actin cytoskeleton. Indeed, in wild-type lenses, γS and F-actin colocalize along the fiber cell plasma membrane. Relative levels of F-actin and G-actin in wild-type and KO lenses were estimated from fluorescent staining profiles and from isolation of actin fractions from whole lenses. Both methods showed a two-fold reduction in the F-actin/G-actin ratio in KO lenses, whereas no difference in tubulin organization was detected. In vitro experiments showed that recombinant mouse γS can directly stabilize F-actin. This suggests that γS may have a functional role related to actin, perhaps in 'shepherding' filaments to maintain the optical properties of the lens cytoplasm and normal fiber cell maturation.

Original languageEnglish (US)
Pages (from-to)2892-2904
Number of pages13
JournalFEBS Journal
Volume279
Issue number16
DOIs
StatePublished - Aug 2012

    Fingerprint

Keywords

  • actin cytoskeleton
  • crystallins
  • knock-out mouse
  • organelles

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this