Dichmann Darwin S, Walentek Peter, Harland Richard M
Department of Molecular & Cell Biology, 142 Life Sciences Addition #3200, University of California, Berkeley, Berkeley, CA 94720-3200, USA.
Department of Molecular & Cell Biology, 142 Life Sciences Addition #3200, University of California, Berkeley, Berkeley, CA 94720-3200, USA.
Cell Rep. 2015 Feb 3;10(4):527-36. doi: 10.1016/j.celrep.2014.12.046. Epub 2015 Jan 22.
Alternative splicing is pervasive in vertebrates, yet little is known about most isoforms or their regulation. transformer-2b (tra2b) encodes a splicing regulator whose endogenous function is poorly understood. Tra2b knockdown in Xenopus results in embryos with multiple defects, including defective somitogenesis. Using RNA sequencing, we identify 142 splice changes (mostly intron retention and exon skipping), 89% of which are not in current annotations. A previously undescribed isoform of wnt11b retains the last intron, resulting in a truncated ligand (Wnt11b-short). We show that this isoform acts as a dominant-negative ligand in cardiac gene induction and pronephric tubule formation. To determine the contribution of Wnt11b-short to the tra2b phenotype, we induce retention of intron 4 in wnt11b, which recapitulates the failure to form somites but not other tra2b morphant defects. This alternative splicing of a Wnt ligand adds intricacy to a complex signaling pathway and highlights intron retention as a regulatory mechanism.
可变剪接在脊椎动物中普遍存在，但对于大多数异构体及其调控机制却知之甚少。transformer-2b（tra2b）编码一种剪接调节因子，其内源性功能尚不清楚。在非洲爪蟾中敲低Tra2b会导致胚胎出现多种缺陷，包括体节发生缺陷。通过RNA测序，我们鉴定出142个剪接变化（主要是内含子保留和外显子跳跃），其中89%不在当前注释中。一种先前未描述的wnt11b异构体保留了最后一个内含子，产生了一个截短的配体（Wnt11b-short）。我们表明，这种异构体在心脏基因诱导和前肾小管形成中作为一种显性负性配体发挥作用。为了确定Wnt11b-short对tra2b表型的贡献，我们诱导wnt11b中的第4内含子保留，这重现了体节形成失败的情况，但没有重现其他tra2b morphant缺陷。这种Wnt配体的可变剪接增加了复杂信号通路的复杂性，并突出了内含子保留作为一种调控机制。
