title: Canonical Wnt signalling regulates epithelial patterning by modulating levels of laminins in zebrafish appendages.
abstract: 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.
authors.affiliation: Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India.
authors.forename: Monica
authors.initials: M
authors.lastname: Nagendran
authors.affiliation: Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India.
authors.forename: Prateek
authors.initials: P
authors.lastname: Arora
authors.affiliation: Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India.
authors.forename: Payal
authors.initials: P
authors.lastname: Gori
authors.affiliation: Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India.
authors.forename: Aditya
authors.initials: A
authors.lastname: Mulay
authors.affiliation: Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India.
authors.forename: Shinjini
authors.initials: S
authors.lastname: Ray
authors.affiliation: Indian Institute of Science Education and Research, Pune 411008, India.
authors.forename: Tressa
authors.initials: T
authors.lastname: Jacob
authors.affiliation: Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India mahendras@tifr.res.in.
authors.forename: Mahendra
authors.initials: M
authors.lastname: Sonawane
mesh_terms: D000818:Animals; D004848:Epithelium / Q000196:embryology*; D005121:Extremities / Q000196:embryology*; D017403:In Situ Hybridization; D007797:Laminin / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009024:Morphogenesis / Q000502:physiology; D060888:Real-Time Polymerase Chain Reaction; D060449:Wnt Signaling Pathway / Q000502:physiology*; D015027:Zebrafish / Q000196:embryology*
chemical_list: D007797:Laminin
keywords: Appendages; Epithelial cell shapes; Laminin; Median fin fold; Wnt signalling; Zebrafish