The molecular mechanisms responsible for axis establishment during non‐embryonic processes remain elusive. The planarian flatworm is an ideal model organism to study body axis polarization and patterning in vivo. Here, we identified a homolog of the TBX2/3 in the planarian Dugesia japonica. RNA interference (RNAi) knockdown of TBX2/3 results in the ectopic formation of protrusions in the midline of the dorsal surface which shows an abnormal expression of midline and ventral cell markers. Additionally, the TBX2/3 RNAi animals also show the duplication of expression of the boundary marker at the lateral edge. Furthermore, TBX2/3 is expressed in muscle cells and co‐expressed with bmp4. Inhibition of bone morphogenetic protein (BMP) signaling reduces the expression of TBX2/3 at the midline. These results suggest that TBX2/3 RNAi results in phenotypic characters caused by inhibition of the BMP signal, indicating that TBX2/3 is required for DV and ML patterning, and might be a downstream gene of BMP signaling.

中文翻译：

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涡虫的背腹和内侧-外侧极性再生需要TBX2/3

在非胚胎过程中负责轴建立的分子机制仍然难以捉摸。涡虫扁虫是研究体内体轴极化和图案的理想模式生物。在这里，我们在涡虫Dugesia japonica 中鉴定了TBX2/3的同源物。TBX2/3 的RNA 干扰 (RNAi) 敲低导致背表面中线异位形成突起，显示中线和腹侧细胞标记物的异常表达。此外，TBX2/3 RNAi 动物还显示出边界标记在侧边缘的重复表达。此外，TBX2/3在肌肉细胞中表达并与bmp4共表达. 骨形态发生蛋白 (BMP) 信号的抑制降低了TBX2/3在中线的表达。这些结果表明TBX2/3 RNAi 导致 BMP 信号抑制引起的表型特征，表明TBX2/3是 DV 和 ML 模式所必需的，并且可能是 BMP 信号传导的下游基因。