Fig. 8.
Concept diagram. A and B: cartilage is necessary for proper tracheal epithelial differentiation and metabolism and regulation of inflammatory-related gene expression in embryonic trachea. Tgf-β ligands, C1qtnf2/3 and melanoma inhibitory activity 1 (Mia1) proteins, are normally secreted by tracheal cartilage and, thus, mediate expression of inflammatory genes by the trachea. TGF-β signaling pathway is pivotal for ontogeny of tracheal basal cells but negatively regulates Clara/club cell differentiation. C1qtnf2/3 peptides are secreted by the cartilage and may contribute to glycogen regulation in tracheal epithelium. Expression of C1qtnf2/3 is reduced in the mutant Sox9Δ/Δ trachea. C: phenotypes across the different experimental systems. Values are means ± SD from 3 independent experiments.