Expression of Drosophila omb-related T-box genes in the developing human and mouse neural retina

PURPOSE. To examine the role of Drosophila optomotor blind (omb)-related T- box genes in development of human and mouse retina. METHODS. Mouse Tbx2, Tbx3, and Tbx5 and human TBX2 cDNAs were isolated from retinal cDNA libraries by hybridization to the Drosophila omb gene. Gene e xpression patterns in developing retina were analyzed by in situ hybridizat ion. RESULTS. TBX2/Tbx2, TBX3/Tbx3, and TBX5/Tbx5 were expressed asymmetrically across the embryonic neural retina with highest levels of mRNA within dorsa l and peripheral retina. The dorsoventral gradient of TBX2 expression disap peared before the ganglion cell layer (GCL) formed. Its expression then bec ame restricted to the inner neuroblastic retina and later to the GCL and in ner nuclear layer (INL). The dorsal expression domains of TBX5/7Tbx5 and TB X3/Tbx3 were maintained during formation of the GCL. As the retina matured, TBX3/Tbx3 expression was restricted to the INL, and TBX5/Tbx5 was expresse d within the GCL. CONCLUSIONS. The expression pattern of TBX2, TBX3, and TBX5 within the deve loping retina supports the idea that the encoded transcription factors play a role in providing positional information important for topographic mappi ng and in differentiation of distinct cell types across the laminar axis of the retina.