Keeping an eye on gene expression

The retina contains neuronal cells (including photoreceptors) and non-neuronal retinal pigment epithelium (RPE). In January 8 Proceedings of the National Academy of Sciences, Dror Sharon and colleagues at Harvard Medical School describe characterisation of gene expression profiles in the human eye using the SAGE (serial analysis of gene expression) technology (Proc Natl Acad Sci USA 2002, 99:315-320).

They prepared SAGE libraries from the peripheral retina, the macula and the RPE of two individuals (an 88 year-old woman and a 44 year-old man) and examined over 320,000 SAGE tags. They found a large number of unassigned tags in the RPE library (38%) suggesting tissue-specific expression. The genes most highly expressed in the retina include several encoding proteins involved in phototransduction and energy metabolism.

The RPE pattern differed from that of the neural retina and included many genes involved in protein degradation and translation. Sharon et al. found evidence...