RESTRICTED EXPRESSION OF A NEW PAIRED-CLASS HOMEOBOX GENE IN NORMAL AND REGENERATING ADULT GOLDFISH RETINA

We describe the cloning and expression pattern of a new paired-class h omeobox gene, Vsx-1, in the continuously growing retina of the goldfis h. Vsx-1 belongs to a subset of paired-class homeobox genes that lack a second DNA binding domain, the paired-domain, and is closely related to the C. elegans ceh-10 gene. In the adult goldfish, Vsx-1 expressio n is restricted to the neural retina. In the central, mature retina, V sx-1 mRNA is synthesized in a subset of differentiated cells in the in ner nuclear layer in a pattern suggestive of bipolar cells. In immatur e retina, adjacent to the retinal margin, Vsx-1 is expressed in a rela tively broader subset of newly postmitotic cells but is downregulated in some of these cells to form the mature expression pattern. Followin g retinal injury, during the early phase of regeneration, Vsx-1 mRNA s ynthesis appears to be upregulated in cells in the inner nuclear layer and is expressed de novo in cells outside this layer. By virtue of it s identity as a transcriptional regulatory gene and its patterns of ex pression, we speculate that Vsx-1 may stabilize the differentiated sta te of a subset of cells in the inner nuclear layer and may be involved in cellular differentiation during retinal development and regenerati on. (C) 1994 Wiley-Liss, Inc.