Genomic Profiling of Mixer and Sox17beta Targets During Xenopus Endoderm Development. Xenopus laevis

The transcription factors Mixer and Sox17beta have well characterized roles in endoderm specification during Xenopus embryogenesis. In order to more thoroughly understand the mechanisms by which these endodermal regulators act, we expressed Mixer and Sox17beta in naïve ectodermal tissue and, using oligonucleotide-based microarrays, compared their genomic transcriptional profile to that of unaffected tissue. Using this novel approach, we identified 71 transcripts that are upregulated by Mixer or Sox17beta, 63 of which have previously uncharacterized roles in endoderm development. Furthermore, an in situ hybridization screen using antisense probes for several of these clones identified six targets of Mixer and/or Sox17beta that are expressed in the endoderm during gastrula stages, providing new and regional markers of the endoderm. Our results contribute further insight into the functions of Mixer and Sox17beta and bring us closer to understanding at the molecular level the pathways that regulate endoderm development. Keywords: comparative genomic response to cell type specification Overall design: Three samples (uninjected control, Mixer injected, Sox17beta injected), two replicates each.

转录因子Mixer与Sox17beta在爪蟾（Xenopus）胚胎发生过程中的内胚层特化环节中，功能已被广泛阐明。为更深入阐明这些内胚层调控因子的作用机制，我们将Mixer与Sox17beta在未受诱导的外胚层组织中过表达，并借助基于寡核苷酸的微阵列，将其全基因组转录谱与未处理对照组织进行比对。通过这一新颖的实验策略，我们共鉴定出71个受Mixer或Sox17beta上调的转录本，其中63个在内胚层发育过程中此前尚未被明确其功能。此外，我们针对其中部分克隆使用反义探针开展原位杂交（in situ hybridization）筛选，共鉴定出6个在原肠胚阶段的内胚层中表达的Mixer和/或Sox17beta靶基因，为内胚层提供了全新的区域特异性标记物。本研究结果进一步深化了我们对Mixer与Sox17beta功能的认知，并帮助我们在分子层面更贴近阐明调控内胚层发育的信号通路。关键词：细胞类型特化的比较基因组应答 实验设计概述：共设置3组样本（未注射对照组、Mixer注射组、Sox17beta注射组），每组设置2个生物学重复。