Perturbed development of cranial neural crest cells in association with reduced sonic hedgehog signaling underlies the pathogenesis of retinoic-acid-induced cleft palate

• Published in: Disease models & mechanisms Vol. 12; no. 10
• Main Authors: Wang, Qi, Kurosaka, Hiroshi, Kikuchi, Masataka, Nakaya, Akihiro, Trainor, Paul A, Yamashiro, Takashi
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Ltd 01-10-2019; The Company of Biologists
• Subjects: Animals; Apoptosis; Birth defects; Bones; Cartilage; Cleft Palate - metabolism; Cleft Palate - pathology; craniofacial development; Embryo, Mammalian - metabolism; Embryo, Mammalian - pathology; embryogenesis; Embryonic Development; Embryos; Female; Hedgehog Proteins - metabolism; Hybridization; Investigations; Mice, Inbred ICR; Models, Biological; Neural Crest - pathology; Pathogenesis; retinoic acid; shh; Signal Transduction; Skull - pathology; SOXE Transcription Factors - metabolism; Tretinoin; vitamin a; Craniofacial development; Vitamin A; Embryogenesis; Shh; Retinoic acid; Apoptosis
• ISSN: 1754-8403; 1754-8411; 1754-8411
• DOI: 10.1242/dmm.040279

Cleft palate (CP) is one of the most common congenital craniofacial anomalies in humans and can be caused by either single or multiple genetic and environmental factor(s). With respect to environmental factors, excessive intake of vitamin A during early pregnancy is associated with increased incidence of CP in offspring both in humans and in animal models. Vitamin A is metabolized to retinoic acid (RA); however, the pathogenetic mechanism of CP caused by altered RA signaling during early embryogenesis is not fully understood. To investigate the detailed cellular and molecular mechanism of RA-induced CP, we administered all-trans RA to pregnant mice at embryonic day (E)8.5. In the RA-treated group, we observed altered expression of
, which marks cranial neural crest cells (CNCCs). Disruption of
expression was also observed at E10.5 in the maxillary component of the first branchial arch, which gives rise to secondary palatal shelves. Moreover, we found significant elevation of CNCC apoptosis in RA-treated embryos. RNA-sequencing comparisons of RA-treated embryos compared to controls revealed alterations in Sonic hedgehog (Shh) signaling. More specifically, the expression of
and its downstream genes
and
was spatiotemporally downregulated in the developing face of RA-treated embryos. Consistent with these findings, the incidence of CP in association with excessive RA signaling was reduced by administration of the Shh signaling agonist SAG (Smoothened agonist). Altogether, our results uncovered a novel mechanistic association between RA-induced CP with decreased Shh signaling and elevated CNCC apoptosis.