Abstract
Abstract: :
Purpose: Retinal ganglion cells (RGC) play essential roles in the visual pathway, and are the substrates for damage in glaucoma and other optic neuropathies. Although there is increasing understanding of their physiology and mechanisms of disease-associated cell death, relatively little is known about the molecules that define a RGC, and control how it differentiates and responds to various external stimuli. In order to learn more about the genes that determine RGC development and function, we initiated a project to profile the genes expressed by RGCs. Methods: Retinal ganglion cells were isolated from postnatal rats by immunopanning. A RGC cDNA library was constructed using SMART technology (Clontech), and cDNA sequencing was performed by automated methods. Results: Four thousand clones were randomly picked from the cDNA library and sequenced. After clustering, database searching of Genbank showed 1470 clusters matching Unigene entries, and 584 clusters with no Unigene match. The gene expression profile obtained was similar to those of neuronal tissues, and differed from that of whole retina; for example photoreceptor genes such as rhodopsin were not encountered. Functional classification of the largest 100 gene clusters showed about 40% involved with energy production or protein synthesis/modification. Neuronal synaptic and lysosomal/vesicular functions were the next largest subgroup (20%). Signal transduction, oxidation/antioxidant genes, and calcium homeostasis genes were also highly represented. Unknown genes, either with highly restricted expression patterns in the CNS, or not previously encountered even in the form of ESTs, are being studied. Conclusions: We have established an initial gene expression profile of purified retinal ganglion cells, including genes that have not been identified through previous EST sequencing efforts. Ongoing analysis will hopefully provide further insights into the molecular basis of the ganglion cell phenotype, and identify genes that may be important in ganglion cell function and disease.
Keywords: gene/expression • retina • ganglion cells