Expression patterns of neurturin and its receptor components in developing and degenerative mouse retina

PURPOSE. Neurturin (NTN) and, its receptor components (GFR alpha 2 and Ret) play an important role in the survival of different populations of neurons in the central and peripheral nervous systems. To gain insight into their possible functions throughout normal retinal development and during retinal neuronal apoptosis, the retinal distribution of expression of NTN and GFR alpha 2 mRNAs and Ret protein were compared in control and retinal degeneration (rd) mice. METHODS. Eyes from control and rd animals were fixed in paraformaldehyde before sectioning. For in situ hybridization, retinal sections were hybridized with S-35-radiolabeled sense and antisense riboprobes for murine NTN and GFR alpha 2 and were autoradiographed. Ret localization was detected by immunofluorescence. RESULTS. Neurturin mRNA. expression was modulated through normal postnatal retinal development and was localized primarily to the inner retina and photoreceptor outer segments. GFR alpha 2 mRNA displayed a diffuse developmental pattern of expression, but in the mature normal retina, NTN and GFR alpha 2 mRNAs were more closely colocalized. Ret protein was localized particularly at the outer segments of photoreceptors, inner retina, and ganglion cell layers, but there were no prominent differences among genotypes. Increased NTN mRNA expression was detected in the retinal pigment epithelium and neural retina in concert with photoreceptor degeneration in rd mouse. In contrast, the level of GFR alpha 2 mRNA mas lower in rd compared with that in normal retina. CONCLUSIONS. These results suggest that NTN and its receptor are involved in retinal postnatal development and maintenance and that alterations in their transcription patterns are associated with inherited retinal degeneration.