Expression patterns of neurturin and its receptor components in developingand 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 degenera tion (rd) mice. METHODS. Eyes from control and rd animals were fixed in paraformaldehyde be fore sectioning. For in situ hybridization, retinal sections were hybridize d with S-35-radiolabeled sense and antisense riboprobes for murine NTN and GFR alpha 2 and were autoradiographed. Ret localization was detected by imm unofluorescence. RESULTS. Neurturin mRNA. expression was modulated through normal postnatal retinal development and was localized primarily to the inner retina and pho toreceptor outer segments. GFR alpha 2 mRNA displayed a diffuse development al pattern of expression, but in the mature normal retina, NTN and GFR alph a 2 mRNAs were more closely colocalized. Ret protein was localized particul arly at the outer segments of photoreceptors, inner retina, and ganglion ce ll layers, but there were no prominent differences among genotypes. Increas ed NTN mRNA expression was detected in the retinal pigment epithelium and n eural retina in concert with photoreceptor degeneration in rd mouse. In con trast, 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 i n retinal postnatal development and maintenance and that alterations in the ir transcription patterns are associated with inherited retinal degeneratio n.