Genetic Requirement of talin1 for Proliferation of Cranial Neural Crest Cells during Palate Development

Craniofacial malformations are among the most common congenital anomalies. Cranial neural crest cells (CNCCs) form craniofacial structures involving multiple cellular processes, perturbations of which contribute to craniofacial malformations. Adhesion of cells to the extracellular matrix mediates bidirectional interactions of the cells with their extracellular environment that plays an important role in craniofacial morphogenesis. Talin (tln) is crucial in cell-matrix adhesion between cells, but its role in craniofacial morphogenesis is poorly understood.

Talin gene expression was determined by whole mount in situ hybridization. Craniofacial cartilage and muscles were analyzed by Alcian blue in Tg(mylz2:mCherry) and by transmission electron microscopy. Pulse-chase photoconversion, 5-ethynyl-2'-deoxyuridine proliferation, migration, and apoptosis assays were performed for functional analysis.

Expression of tln1 was observed in the craniofacial cartilage structures, including the palate. The Meckel's cartilage was hypoplastic, the palate was shortened, and the craniofacial muscles were malformed in tln1 mutants. Pulse-chase and EdU assays during palate morphogenesis revealed defects in CNCC proliferation in mutants. No defects were observed in CNCC migration and apoptosis.

The work shows that tln1 is critical for craniofacial morphogenesis in zebrafish. Loss of tln1 leads to a shortened palate and Meckel's cartilage along with disorganized skeletal muscles. Investigations into the cellular processes show that tln1 is required for CNCC proliferation during palate morphogenesis. The work will lead to a better understanding of the involvement of cytoskeletal proteins in craniofacial morphogenesis.