Homeobox genes and vertebrate retina development - 網膜の初期発生、背腹軸形成から光受容体細胞分化まで -

古川貴久 博士
ハーバード大学医学部遺伝学教室

　The vertebrate retina is a relatively well described and accessible structure that provides an excellent model system for studies of patterning and cell fate determination within the central nervous system. Previous studies have identified a number of transcription factors that have putative roles in development of the vertebrate retina, including homeodomain proteins such as Pax6, chx10 and Brn3b. For example, Chx10 and Brn3b appear to be essential for development of bipolar cells and ganglion cells, respectively. Since the retina has several distinct neuronal types with diversity of their physiological and morphological properties, we have hypothesized that many yet unidentified transcriptional regulators exist.We have recently identified three novel homeobox genes, which are namely rax/Rx, Crx and vex. Rax is expressed in retinal progenitors, and involved in early eye formation and retinal cell differentiation. Crx is the only transcription factor reported so far which is expressed specifically in photoreceptor cells in the retina. Mutations of human Crx are associated with the retinal degeneration disease, cone-rod dystrophy-2. We have made a knock-out mouse of Crx, and its phenotype will be reported. A novel homeobox gene, vex of the retina.