Fox proteins are modular competency factors for facial cartilage and tooth specification

Abstract

Facial form depends on the precise positioning of cartilage, bone, and tooth fields in the embryonic pharyngeal arches. How complex signaling information is integrated to specify these cell types remains a mystery. We find that modular expression of Forkhead domain transcription factors (Fox proteins) in the zebrafish face arises through integration of Hh, Fgf, Bmp, Edn1 and Jagged-Notch pathways. Whereas loss of C-class Fox proteins results in reduced upper facial cartilages, loss of F-class Fox proteins results in distal jaw truncations and absent midline cartilages and teeth. We show that Fox proteins are required for Sox9a to promote chondrogenic gene expression. Fox proteins are sufficient in neural crest-derived cells for cartilage development, and neural crest-specific misexpression of Fox proteins expands the cartilage domain but inhibits bone. These results support a modular role for Fox proteins in establishing the competency of progenitors to form cartilage and teeth in the face.

Morphogenesis and differentiation of embryonic vascular smooth muscle cells in zebrafish

“…Similar to the morpholino knockdown 381 of foxc1a and foxc1b (French et al, 2014), loss of both paralogs is required for significant loss of 382 smooth muscle coverage, with foxc1a having a stronger effect on smooth muscle differentiation 383 13 than foxc1b. There is known genetic redundancy in zebrafish foxc1 genes (Jolanta M. 384 Xu et al, 2018). foxc1a has a similar expression pattern, to foxc1b 385 (Jolanta M. Xu et al, 2018) and Fox family members are known to play 386 redundant roles in mice (Kume et al, 2001;Seo and Kume, 2006).…”

“…As foxc1b is expressed in cells that differentiate into acta2 positive smooth muscle cells, we next 307 tested whether foxc1b and its paralog foxc1a are necessary for smooth muscle development. The 308 two genes have similar expression patterns, and foxc1a and foxc1b can compensate for each 309 other (Jolanta M. Skarie and Link, 2009;Xu et al, 2018). foxc1a is highly 310 expressed in our acta2 dataset, thus we scored for acta2:EGFP positive smooth muscle cell 311 coverage of the ventral aorta in foxc1a and foxc1b compound mutants.…”

“…1A, 173 C, E, G, I, and K). Specifically, foxc1b is expressed in the region of the aortic arches, jaw, 174 ceratohyal (Schilling et al, 1996;Knight, 2003;Filipek-Górniok et al, 2015;Xu et al, 2018) and 175 in the periocular mesenchyme in the ventral head. Furthermore, foxc1b mRNA expression 176 overlaps with foxc1b:EGFP transgenic expression in the ventral aorta, aortic arch arteries, and 177 ceratohyal at 2 and 4 dpf, suggesting EGFP in the transgenic fish line mimics endogenous mRNA 178 expression ( Fig.…”

notum1, acting downstream of pitx2, is essential for proper eye and craniofacial development

“…Embryos were imaged and stored at 4°C in 50% glycerol and 0.1% KOH. Flat-mount dissection techniques were provided courtesy of Xu et al (Xu et al, 2018). Craniofacial structures were identified as presented by Piotrowski et al and Xu et al (Piotrowski et al, 1996;Xu et al, 2018).…”

“…Flat-mount dissection techniques were provided courtesy of Xu et al (Xu et al, 2018). Craniofacial structures were identified as presented by Piotrowski et al and Xu et al (Piotrowski et al, 1996;Xu et al, 2018). Whole-mount and flat-mount images were obtained on a Nikon SMZ1500 dissection microscope (Nikon Instruments Inc., Melville, NY).…”