Abstract
Purpose::
Identification and characterization of novel genes expressed in the retina help to identify molecular defects that cause retinal degenerations. Northern blot analysis shows that Tweety homolog 2 (Ttyh2), a novel gene, is highly expressed in the mouse retina. Ttyh2 is located at human 17q24 and three different transcripts are expressed in the mouse retina. Other members of the Tweety gene family include Ttyh1, located at human chromosome 19q13.4, and Ttyh3, located at human chromosome 7p22. These Tweety homolog genes are members of a novel gene family that is conserved through evolution. They encode predicted transmembrane proteins whose function is unknown. The goal of this study was to determine the expression patterns of Ttyh1, Ttyh2 and Ttyh3 in the mouse.
Methods::
RNA was isolated from a variety of mouse organs including the retina, optic nerve, brain, and spinal cord. cDNA was synthesized from the RNA. Primers specific for Ttyh1, Ttyh2, Ttyh3, and beta-actin were used in reverse transcriptase PCR (rtPCR) experiments. The rtPCR products were separated by gel electrophoresis after which the gels were photographed and analyzed.
Results::
rtPCR shows that Ttyh1, Ttyh2 and Ttyh3 are expressed in the CNS including the retina, brain and spinal cord. Three forms of the Ttyh2 transcript are detected in the retina but differential expression of these transcripts is found in other regions of the nervous system.
Conclusions::
Knowledge of the expression patterns of the different members of the Tweety homolog gene family may begin to elucidate their function. rtPCR experiments demonstrate that Ttyh1, Ttyh2 and Ttyh3 are all expressed in the retina. However, each gene may be expressed by different retinal cell types and perform different functions. Studies from other groups suggest a functional diversity within the Tweety homolog gene family. Identification and characterization of novel genes, such as the different members of the Tweety homolog gene family, will provide us with additional tools to study the function of the retina in health and disease.
Keywords: gene/expression • retina