Characterization of NGF, trkA (NGFR) and p75 (NTR) in retina of mice lacking reelin glycoprotein

Both Reelin and Nerve Growth Factor (NGF) exert crucial roles in retinal development. Retinogenesis is severely impaired in E-reeler mice, a model of Reelin deficiency showing specific Green Fluorescent Protein expression in Rod Bipolar Cells (RBCs). Since no data are available on Reelin and NGF cross-talk, NGF and trkA(NGFR)/ p75(NTR) expression was investigated in retinas from E-reeler versus control mice, by confocal microscopy, Western blotting, and real time PCR analysis. A scattered increase of NGF protein was observed in the Ganglion Cell Layer and more pronounced in the Inner Nuclear Layer (INL). A selective increase of p75(NTR) was detected in most of RBCs and in other cell subtypes of INL. On the contrary, a slight trend towards a decrease was detected for trkA(NGFR), albeit not significant. Confocal data were validated by Western blot and real time PCR. Finally, the decreased trkA(NGFR)/ p75(NTR) ratio, representative of p75(NTR) increase, significantly correlated with E-reeler versus E-control. These data indicate that NGF-trkA(NGFR)/ p75(NTR) is affected in E-reeler retina and that p75(NTR) might represent the main NGF receptor involved in the process. This first NGF-trkA(NGFR)/ p75(NTR) characterization suggests that E-reeler might be suitable for exploring Reelin-NGF cross-talk, representing an additional information source in those pathologies characterized by retinal degeneration.