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Abstract

AP-2 transcription factors play important roles in the regulation of gene expression during development. Four of the five members of the AP-2 family (AP-2 alpha, AP-2 beta, AP-2 gamma and AP-2 delta) have previously been shown to be expressed in developing retina. Mouse knockouts have revealed roles for AP-2 alpha, AP-2 beta and AP-2 delta in retinal cell specification and function. Here, we show that the fifth member of the AP-2 family, AP-2 epsilon, is also expressed in amacrine cells in developing mammalian and chicken retina. Our data indicate that there are considerably fewer AP-2 epsilon-positive cells in the developing mouse retina compared to AP-2 alpha, AP-2 beta and AP-2 gamma-positive cells, suggesting a specialized role for AP-2 epsilon in a subset of amacrine cells. AP-2e, which is restricted to the GABAergic amacrine lineage, is most commonly co-expressed with AP-2 alpha and AP-2 beta, especially at early stages of retinal development. Coexpression of AP-2 epsilon and AP-2 gamma increases with differentiation. Analysis of previously published Drop-seq data from single retinal cells supports co-expression of multiple AP-2s in the same cell. Since AP-2s bind to their target sequences as either homodimers or heterodimers, our work suggests spatially-and temporally-coordinated roles for combinations of AP-2 transcription factors in amacrine cells during retinal development.