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E. J. de la Rosa, J. Baleriola; A Possible Role of the DNA Repair Process in Retinal Development. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1307.
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© ARVO (1962-2015); The Authors (2016-present)
During retinal development, physiological cell death affects all cell types including progenitors, young neurons, as well as mature neurons and glial cells. Thus, correct retinal development is achieved by an orchestrated balance of proliferation, differentiation and cell death. However, the functional basis of cell death is not fully understood. On the other hand, several genetically-modified mouse model systems defective in double-strand break DNA repair show disruption of central nervous system development. We try to evaluate the contribution of the DNA repair process to retinal neurogenesis.
Embryonic retinas (E14.5) from C57BL/6J mice were cultured for 6 hours in a defined medium and treated with 10 µM etoposide (topoisimerase II inhibitor), 200 nM NU7026 (DNA-PK inhibitor), 200 nM CGK733 (ATM/ATR inhibitor), 38 µM Boc-D-fmk (caspase inhibitor) or 5 µM BrdU. After the culture, retinas were processed for immunohistochemistry, western blot or TUNEL to determine the effectiveness of the treatments and their effects on proliferation, differentiation and cell death.
Embryonic retinas from C57BL/6J mice showed an association between H2AX activation and physiological cell death. Pharmacological inhibition of ATM/ATR and DNA-PK increased caspase-dependent cell death. These pharmacological approaches did alter neither proliferation (as measured by BrdU incorporation) nor cell-cycle exit (double BrdU, TUJ-1, stained cells), but the final number of neurons.
Our results suggest that generation of double-strand breaks may account for at least part of naturally occurring early neural cell death in the retina. Young neurons, at least at E14.5, appear to be selectively dependent on the repair process.
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