Elastase is not required for l-DNase II activation during apoptosis in developing chicken neural retina

During retinal development, the neuronal death is carried out by the mechanism of apoptosis. Among the different endonucleases activated, l-DNase II seems to be responsible for most of DNA degradation in this tissue. l-DNase II derives from LEI (Leukocyte Elastase Inhibitor) by a post-translational modification carried out by elastase in apoptosis induced in vitro. In this study, we investigated whether elastase could be implicated in apoptosis occurring during retinal development. Although elastase and LEI/elastase complex are colocalized in retinal sections, the LEI/elastase complex, detected by Western blot, does not change at all stages of development. However, at pH 4 retinal extracts show an enhanced activation of the l-DNase II. These results suggest that an acid protease, such as a cathepsin, may be implicated in neuronal retinal apoptosis.