PURPOSE

The photoreceptor conserved element-1 (PCE-1) sequence is found in the transcriptional regulatory regions of many genes expressed in photoreceptors. The gene product functions by binding to PCE-1 sites. However, other transcriptional regulators have also been reported to bind to PCE-1. One of these, , is expressed in retinal progenitor and bipolar cells. The purpose of this study is to identify gene products and characterize gene product expression and function with respect to the PCE-1 site.

METHODS

gene products were amplified with PCR. Expression patterns were determined with in situ hybridization using whole or sectioned embryos and digoxigenin- or fluorescein-labeled antisense riboprobes. DNA binding characteristics of the gene products were analyzed with electrophoretic mobility shift assays (EMSAs) using in vitro translated proteins and radiolabeled oligonucleotide probes. Gene transactivation assays were performed using luciferase-based reporters and in vitro transcribed effector gene products, injected into embryos.

RESULTS

We identified one and two gene products. The two gene products are generated by alternate mRNA splicing. We verified that these gene products are expressed in the developing retina and that expression resolves into distinct cell types in the mature retina. Finally, we found that gene products can bind the PCE-1 site in vitro and that the two isoforms have different gene transactivation activities.

CONCLUSIONS

gene products are expressed in the developing and mature neural retina. gene products can bind the PCE-1 site in vitro and influence the expression of a rhodopsin promoter-luciferase reporter gene. The two isoforms of have different gene transactivation activities in this reporter gene system.