Canonical Wnt signalling regulates epithelial patterning by modulating levels of laminins in zebrafish appendages

ECM alterations in Fndc3a (Fibronectin Domain Containing Protein 3A) deficient zebrafish cause temporal fin development and regeneration defects

“…Future experiments will have to clarify if binding of Fndc3a to integrins is abandoned in fndc3a wue1/wue1 mutants, thereby directly influencing cell adhesion, basal epithelium establishment, and signaling 52,53 . This idea is supported by the similarity of fndc3a wue1/wue1 fin fold defects to laminin ( lmna5) and integrin ( itga3 ) mutants 6,9,21 and the occurrence of aberrant cells in the epidermal layer of regenerates in the fndc3a wue1/wue1 mutants. Moreover, our experiments do not rule out a potential intracellular function of Fndc3a.…”

“…The process of median fin fold development is tightly regulated by modulation of epidermal cell shape and correct ECM assembly 8,9 . TP63 positive epidermal cells are still present in the fndc3a wue1/wue1 mutants during median fin fold development 20 to 48 hpf, but show reduced numbers at ventral positions, delayed ventral fin fold growth and altered morphological properties.…”

“…Already more than 30 years ago changes of epidermal cell shape and modulation of the extracellular matrix (ECM) have been described as one of the essential factors for correct median fin fold and caudal fin morphogenesis in zebrafish 8 . Recently, the Wnt signaling pathway has been shown crucial for regulation of epithelial cell morphology by modulating laminin levels and thereby orchestrating correct ECM patterning in growing fins 9 . These early cellular steps of caudal fin development are prerequisites for subsequent processes; i.e.…”

“…For both processes correct epidermal cell function, epithelial cell structure, and actinotrichia fiber assembly are essential to correctly build all skeletal and mesenchymal fin elements 14,19,20 . Structural factors, especially ECM proteins like integrins and laminins, have been implied in regulating Wnt signaling during regeneration and in correct assembly of the teleost fin 6,9,21 . Although a large number of involved “molecular players” have been described to date, not all factors necessary for correct ECM assembly in the regenerating caudal fin or correct median fin fold development and function have been elucidated yet.…”

Canonical Wnt signaling regulates branching morphogenesis of submandibular gland by modulating levels of lama5

“…Rebustini et al (Rebustini et al, 2007) demonstrated the influence of laminin-α5-integrin signaling pathway and the interaction between laminin-α5 (Lama5) and FGFR on SMG branching morphogenesis. And interactions between canonical Wnt signaling and Lama5 were found important for epithelial patterning during appendages development in zebrafish (Nagendran et al, 2015) Liming G et al 6 and dermal papilla development during early hair morphogenesis in mouse (Gao et al, 2008). However, no similar study has been reported in SMG development.…”