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.