Expression of AP-2 in the Developing Chick Retina

AP-2 is a family of transcription factors that play important roles during embryonic development. Two AP-2 genes, AP-2 and AP-2, have previously been characterized in chick retina. Here, we demonstrate that a third member of the chicken AP-2 family, AP-2, is primarily expressed in the retina and brain, with highest levels at embryonic days 7 to 11. By in situ hybridization and immunohistochemical analysis, we show that AP-2 RNA and protein are found in a subset of ganglion cells in embryonic chick retina. Coimmunostaining with anti-Brn3a and anti–AP-2 antibodies indicates that approximately one-third of Brn3a-positive ganglion cells express AP-2. AP-2 RNA but not AP-2 protein is also found in cells located in the outer half of the inner nuclear layer. The spatial and temporal distribution of AP-2 protein in the retina suggests a transient role in a subset of late-born ganglion cells likely involving axonal trafficking or pathfinding. Developmental Dynamics 237:3210 –3221, 2008. © 2008 Wiley-Liss, Inc.