Basal constriction during midbrain–hindbrain boundary morphogenesis is mediated by Wnt5b and focal adhesion kinase

• Main Authors: Jennifer H. Gutzman, Ellie Graeden, Isabel Brachmann, Sayumi Yamazoe, James K. Chen, Hazel Sive
• Format: Article
• Language: English
• Published: The Company of Biologists 2018-11-01
• Series: Biology Open
• Subjects: Basal constriction; Cell shape; Morphogenesis; Zebrafish; Wnt5b; Focal adhesion kinase; Midbrain–hindbrain boundary
• Online Access: http://bio.biologists.org/content/7/11/bio034520

Basal constriction occurs at the zebrafish midbrain–hindbrain boundary constriction (MHBC) and is likely a widespread morphogenetic mechanism. 3D reconstruction demonstrates that MHBC cells are wedge-shaped, and initially constrict basally, with subsequent apical expansion. wnt5b is expressed in the MHB and is required for basal constriction. Consistent with a requirement for this pathway, expression of dominant negative Gsk3β overcomes wnt5b knockdown. Immunostaining identifies focal adhesion kinase (Fak) as active in the MHB region, and knockdown demonstrates Fak is a regulator of basal constriction. Tissue specific knockdown further indicates that Fak functions cell autonomously within the MHBC. Fak acts downstream of wnt5b, suggesting that Wnt5b signals locally as an early step in basal constriction and acts together with more widespread Fak activation. This study delineates signaling pathways that regulate basal constriction during brain morphogenesis.