ISOLATION OF CDNA CLONES ENCODING RICH - A PROTEIN-INDUCED DURING GOLDFISH OPTIC-NERVE REGENERATION WITH HOMOLOGY TO MAMMALIAN 2',3'-CYCLIC-NUCLEOTIDE 3'-PHOSPHODIESTERASES

Using data derived from peptide sequencing of p68/70, a protein double t induced during optic nerve regeneration in goldfish, we have isolate d cDNAs that encode RICH (regeneration-induced CNPase homolog) from a goldfish regenerating retina cDNA library, The predicted RICH protein com prises 411 amino acids, possesses a pI of 4.48, and shows signific ant homology to the mammalian myelin marker enzyme 2',3'-cyclic-nucleo tide 3'-phosphodiesterase (CNPase; EC 3.1.4.37), The mRNA encoding RIC H was demonstrated, by both Northern blot analysis and RNase protectio n assays, to be induced as much as 8-fold in regenerating goldfish ret inas at 20 days after nerve crush. Analysis of total RNA samples from various tissues showed a broad distribution of RICH mRNA, with the hig hest levels observed in gravid ovary. The data obtained strongly sugge st that RICH is identical or very similar to p68/70, The molecular clo ning of RICH provides the means for a more detailed analysis of its fu nction in nerve regeneration. Additionally, the homology of RICH and C NPase suggests that further investigation may provide additional insig ht into the role of these proteins in the nervous system.