| First Author | De Maria A | Year | 2007 |
| Journal | Invest Ophthalmol Vis Sci | Volume | 48 |
| Issue | 12 | Pages | 5638-46 |
| PubMed ID | 18055814 | Mgi Jnum | J:132501 |
| Mgi Id | MGI:3776177 | Doi | 10.1167/iovs.07-0782 |
| Citation | De Maria A, et al. (2007) DNase IIbeta distribution and activity in the mouse lens. Invest Ophthalmol Vis Sci 48(12):5638-46 |
| abstractText | PURPOSE: To map the cellular and subcellular distribution of DNase IIbeta activity in the mouse lens. METHODS: DNase IIbeta-specific activity was determined by assaying lens lysates prepared from wild-type or DNase IIbeta-null mice. Regional nuclease activity was determined by microdissection of lens samples or a tissue-imprinting assay. Subcellular distribution was determined by density-gradient ultracentrifugation. RESULTS: DNase IIbeta transcripts increased 200-fold in abundance during fiber cell formation, and DNase IIbeta activity accounted for approximately 50% of the acid nuclease activity in the cortical fiber cells. Examination of lenses from DNase IIbeta-null mice confirmed that the enzyme was required for denucleation. In wild-type lenses, nuclei were TUNEL positive before denucleation, indicating that 3'-OH DNA ends had accumulated. However, DNase IIbeta-mediated scission generates 3'-PO(4)(-) DNA ends only. This paradoxical finding was explained by the presence of phosphatases that converted the 3'-PO(4)(-) ends produced by DNase IIbeta into 3'-OH ends. DNase IIbeta activity was strongest early in differentiation, where it was associated with the lysosomal fraction. Later, an increasing proportion of DNase IIbeta activity was found in the cytosol. CONCLUSIONS: DNase IIbeta activity correlated with and was necessary for fiber denucleation and was most likely contained initially within fiber cell lysosomes before release into the cytoplasm. |
