Foxg1Organizes Cephalic Ectoderm to Repress Mandibular Fate, Regulate Apoptosis, Generate Choanae, Elaborate the Auxiliary Eye and Pattern the Upper Jaw

Abstract

Gnathostome jaw patterning involves focal instructive signals from the embryonic surface cephalic ectoderm (SCE) to a fungible population of cranial neural crest. The spatial refinement of these signals, particularly for those patterning the upper jaws, is not fully understood. We demonstrate that Foxg1, broadly expressed in the SCE overlying the upper jaw primordia, is required for both neurocranial and viscerocranial development, including the sensory capsules, neurocranial base, middle ear, and upper jaws. Foxg1 controls upper jaw molecular identity and morphologic development by actively inhibiting the inappropriate acquisition of lower jaw molecular identity within the upper jaw primordia, and is necessary for the appropriate elaboration of the λ-junction, choanae, palate, vibrissae, rhinarium, upper lip and auxiliary eye. It regulates intra-epithelial cellular organization, gene expression, and the topography of apoptosis within the SCE. Foxg1 integrates forebrain and skull development and genetically interacts with Dlx5 to establish a single, rostral cranial midline.

Conserved and unique transcriptional features of pharyngeal arches in the skate (Leucoraja erinacea) and evolution of the jaw

“…We observed foxG1 expression in the dorsal domains of the mandibular, hyoid, and gill arches in skate. In mouse, foxG1 functions in the morphogenesis of the forebrain ( Tao and Lai 1992 ; Dou et al 1999 ; Hanashima et al 2002 ), but it is also expressed in the epithelium and mesodermal core of the pharyngeal arches ( Hébert and McConnell 2000 ; Tavares et al 2017 ), and has recently been shown to play a role in neurocranial and pharyngeal skeletal development ( Compagnucci and Depew 2020 ). In skate, we find that foxG1 is initially expressed strongly in the dorsal epithelium and dorsal mesodermal core of each pharyngeal arch at S26 ( fig.…”

Conserved and unique transcriptional features of pharyngeal arches in the skate (Leucoraja erinacea) and evolution of the jaw

“…6A). In mouse, foxG1 functions in the morphogenesis of the forebrain (Tao and Lai, 1992; Dou et al, 1999; Hanashima et al, 2002), and more recently, has been shown to play a role in neurocranial and pharyngeal skeletal development (Compagnucci & Depew, 2020). In skate, we find that foxG1 is expressed in the dorsal epithelium and dorsal core mesoderm of each pharyngeal arch (Fig.…”

Plexina4 and cell survival in the developing zebrafish hindbrain

“…We found no obvious differences between plxna4 mutants and their WT siblings in either the levels or patterns of expression of fgf8a , a key signaling molecule expressed at the midbrain‐hindbrain boundary (Figure 3A,B), 43 pax6a , a regulator of hindbrain segmentation (Figure 3C,D), 44 and sema3fa , a marker of rhombomere 1 (Figure 3E,F). 45 Given the expression of plxna4 in hindbrain‐associated cranial ganglia (Figure 1), we assessed foxg1a 46 and found no obvious differences between plxna4 mutants and their WT siblings (Figure 3G,H).…”