Characterisation of eye-lens DNases: Long term persistence of activity in post apoptotic lens fibre cells

Cristina Arruti, Elisabeth Chaudun, Alicia De Maria, Yves Courtois, Marie France Counis

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Fibre cells in the ocular lens exhibit a constitutive apoptotic process of nuclear degradation that includes chromatin breakage, generating a ladder pattern of DNA fragments. This process is intrinsic to the normal terminal differentiation program. Despite the loss of nucleus and cytoplasmic organelles, the terminal differentiated fibre cells remain in the lens during the whole life span of the individual. The lens cells thus provide a unique system in which to determine the presence and fate of endonucleases once the chromatin has been cleaved. We report here on the presence of DNase activity in nucleated and anucleated lens cells. Using a nuclease gel assay and double-stranded DNA as substrate, we found active 30 and 60 kDa DNases. The enzymatic activities were Ca2+, Mg2+ dependent, and active at neutral pH. The relative amount of these forms changed during development and aging of the lens fibre cells. Both forms were inhibited by Zn2+, aurintricarboxylic acid, and G-actin. The proteins were also separated by SDS-PAGE, renatured after removing SDS and incubated in the presence of native DNA adsorbed to a membrane. Therefore it was possible to demonstrate, by means of a nick translation reaction, that the enzymes produced single strand cuts. Based on these findings we propose that these chick lens nucleases are probably related to DNase I.

Original languageEnglish
Pages (from-to)47-56
Number of pages10
JournalCell Death and Differentiation
Volume2
Issue number1
StatePublished - Dec 1 1995
Externally publishedYes

Keywords

  • Apoptosis
  • Dnase i
  • Lens cells
  • Nucleases

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