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C. Arruti, A. De Maria; DNase I and Condensed Chromatin in Lens Cells Nuclei Degradation . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1242.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Nuclear degradation occurs in the final phases of lens fiber terminal differentiation as well as in apoptosis in epithelial and fiber cells. Our principal objective was to determine whether DNase I is related to DNA cleavage in these processes. Methods: RT-PCR and nucleotide sequencing were used to identify DNase I mRNA in lens cells. Polyclonal anti-DNase I antibodies were raised, affinity purified and used to localize the protein in bovine lens cryosections as well as in cultured epithelial lens cells. Results: Epithelial lens cells, either in vivo as in vitro, produce several DNase I transcripts. One of them is identical to the pancreatic DNase I mRNA. Other transcripts result from alternative splicing and do not produce functional protein. DNase I, located at the cytoplasm of epithelial lens cells, is progressively concentrated around the fiber nucleus and is found inside the nuclear space once lamins are degraded. Highly condensed chromatin, either in terminal differentiated fiber cells or in staurosporin-treated epithelial lens cells, was found associated with DNase I. Conclusions: Lens cells synthesize DNase I. This enzyme is located in secretory organelles and translocates to the cell nucleus during the ultimate phases of chromatin degradation, where it is associated to condensed chromatin clumps.
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