Nagendran Monica, Arora Prateek, Gori Payal, Mulay Aditya, Ray Shinjini, Jacob Tressa, Sonawane Mahendra
Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India.
Indian Institute of Science Education and Research, Pune 411008, India.
Development. 2015 Jan 15;142(2):320-30. doi: 10.1242/dev.118703. Epub 2014 Dec 17.
The patterning and morphogenesis of body appendages - such as limbs and fins - is orchestrated by the activities of several developmental pathways. Wnt signalling is essential for the induction of limbs. However, it is unclear whether a canonical Wnt signalling gradient exists and regulates the patterning of epithelium in vertebrate appendages. Using an evolutionarily old appendage - the median fin in zebrafish - as a model, we show that the fin epithelium exhibits graded changes in cellular morphology along the proximo-distal axis. This epithelial pattern is strictly correlated with the gradient of canonical Wnt signalling activity. By combining genetic analyses with cellular imaging, we show that canonical Wnt signalling regulates epithelial cell morphology by modulating the levels of laminins, which are extracellular matrix components. We have unravelled a hitherto unknown mechanism involved in epithelial patterning, which is also conserved in the pectoral fins - evolutionarily recent appendages that are homologous to tetrapod limbs.
身体附属器（如四肢和鳍）的模式形成和形态发生是由几种发育途径的活动精心编排的。Wnt信号传导对于四肢的诱导至关重要。然而，尚不清楚是否存在经典的Wnt信号梯度并调节脊椎动物附属器中上皮的模式形成。我们以一种进化上古老的附属器——斑马鱼的正中鳍为模型，表明鳍上皮沿近端-远端轴呈现细胞形态的分级变化。这种上皮模式与经典Wnt信号活性梯度严格相关。通过将遗传分析与细胞成像相结合，我们表明经典Wnt信号通过调节层粘连蛋白（细胞外基质成分）的水平来调节上皮细胞形态。我们揭示了一种迄今为止未知的参与上皮模式形成的机制，这种机制在胸鳍中也保守存在，胸鳍是与四足动物四肢同源的进化上较新的附属器。
