Petersen Christian P, Reddien Peter W
Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA.
Science. 2008 Jan 18;319(5861):327-30. doi: 10.1126/science.1149943. Epub 2007 Dec 6.
Planarian flatworms can regenerate heads at anterior-facing wounds and tails at posterior-facing wounds throughout the body. How this regeneration polarity is specified has been a classic problem for more than a century. We identified a planarian gene, Smed-betacatenin-1, that controls regeneration polarity. Posterior-facing blastemas regenerate a head instead of a tail in Smed-betacatenin-1(RNAi) animals. Smed-betacatenin-1 is required after wounding and at any posterior-facing wound for polarity. Additionally, intact Smed-betacatenin-1(RNAi) animals display anteriorization during tissue turnover. Five Wnt genes and a secreted Frizzled-related Wnt antagonist-like gene are expressed in domains along the anteroposterior axis that reset to new positions during regeneration, which suggests that Wnts control polarity through Smed-betacatenin-1. Our data suggest that beta-catenin specifies the posterior character of the anteroposterior axis throughout the Bilateria and specifies regeneration polarity in planarians.
涡虫扁形虫可以在身体各处面向前端的伤口处再生头部，在面向后端的伤口处再生尾部。这种再生极性是如何确定的，在一个多世纪以来一直是个经典问题。我们鉴定出一个涡虫基因Smed-betacatenin-1，它控制再生极性。在Smed-betacatenin-1（RNA干扰）动物中，面向后端的芽基会再生出头部而非尾部。受伤后以及在任何面向后端的伤口处，极性的产生都需要Smed-betacatenin-1。此外，完整的Smed-betacatenin-1（RNA干扰）动物在组织更新过程中会出现前端化现象。五个Wnt基因和一个分泌型卷曲相关蛋白Wnt拮抗剂样基因沿前后轴在特定区域表达，这些区域在再生过程中会重置到新的位置，这表明Wnt通过Smed-betacatenin-1控制极性。我们的数据表明，β-连环蛋白确定了整个两侧对称动物前后轴的后端特征，并确定了涡虫的再生极性。
