Silencing of Smed-βcatenin1 generates radial-like hypercephalized planarians

被引:161
作者
Iglesias, Marta [1 ]
Luis Gomez-Skarmeta, Jose [2 ]
Salo, Emili [1 ]
Adell, Teresa [1 ]
机构
[1] Univ Barcelona, Dept Genet, E-08028 Barcelona, Spain
[2] Univ Pablo Olavide CSIC, Ctr Andaluz Biol Desarrollo, Seville 41013, Spain
来源
DEVELOPMENT | 2008年 / 135卷 / 07期
关键词
beta-catenin; planarians; anteroposterior axis; regeneration;
D O I
10.1242/dev.020289
中图分类号
Q [生物科学];
学科分类号
07 ; 0710 ; 09 ;
摘要
Little is known about the molecular mechanisms responsible for axis establishment during non-embryonic processes such as regeneration and homeostasis. To address this issue, we set out to analyze the role of the canonical Wnt pathway in planarians, flatworms renowned for their extraordinary morphological plasticity. Canonical Wnt signalling is an evolutionarily conserved mechanism to confer polarity during embryonic development, specifying the anteroposterior (AP) axis in most bilaterians and the dorsoventral ( DV) axis in early vertebrate embryos. beta-Catenin is a key element in this pathway, although it is a bifunctional protein that is also involved in cell-cell adhesion. Here, we report the characterization of two beta-catenin homologs from Schmidtea mediterranea (Smed-beta catenin1/2). Loss of function of Smed-beta catenin1, but not Smed-beta catenin2, in both regenerating and intact planarians, generates radial-like hypercephalized planarians in which the AP axis disappears but the DV axis remains unaffected, representing a unique example of a striking body symmetry transformation. The radial-like hypercephalized phenotype demonstrates the requirement for Smed-beta catenin1 in AP axis re-establishment and maintenance, and supports a conserved role for canonical Wnt signalling in AP axis specification, whereas the role of beta-catenin in DV axis establishment would be a vertebrate innovation. When considered alongside the protein domains present in each S. mediterranea beta-catenin and the results of functional assays in Xenopus embryos demonstrating nuclear accumulation and axis induction with Smed-beta catenin1, but not Smed-beta catenin2, these data suggest that S. mediterranea beta-catenins could be functionally specialized and that only Smed-beta catenin1 is involved in Wnt signalling.
引用
收藏
页码:1215 / 1221
页数:7
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