Pairing your Sox: identification of Sox11 partner proteins and interaction domains in the developing neural plate

Sox11, a member of the SoxC family of transcription factors, has distinct functions at different times in neural development. Studies in mouse, frog, chick and zebrafish show that Sox11 promotes neural fate, neural differentiation, and neuron maturation in the central nervous system. These diverse roles are controlled in part by spatial and temporal-specific protein interactions. However, the partner proteins and Sox11-interaction domains underlying these diverse functions are not well defined. Here, we identify partner proteins and the domains of Xenopus Sox11(xSox11) required for protein interaction and function during neurogenesis. Our data show that Sox11 co-localizes and interacts with Pou3f2 and Ngn2 in the anterior neural plate and in early neurons, respectively. We also demonstrate that xSox11 does not interact with Ngn1, a high affinity partner of Sox11 in the mouse cortex, suggesting that Sox11 has species-specific partner proteins. Additionally, we determined that the N-terminus including the HMG domain of xSox11 is necessary for interaction with Pou3f2 and Ngn2, and established a novel role for the N-terminal 46 amino acids in the establishment of placodal progenitors. This is the first identification of partner proteins for Xenopus Sox11 and of domains required for partner protein interactions and distinct roles in neurogenesis.