Adaptive Correction of Craniofacial Defects in Pre-metamorphic Tadpoles Involves Thyroid Hormone-independent Tissue Remodeling

Although it is well established that some organisms can regenerate lost structures, the ability to remodel existing malformed structures has been less well studied. Therefore, in this study we examined the ability of pre-metamorphic tadpoles to self-correct malformed craniofacial tissues. We found that tadpoles can adaptively improve and normalize abnormal craniofacial morphology caused by numerous developmental perturbations. We then investigated the tissue-level and molecular mechanisms that mediate the self-correction of craniofacial defects in pre-metamorphic tadpoles. Our studies revealed that this adaptive response involves morphological changes and the remodeling of cartilage tissue, prior to metamorphosis. RT-qPCR and RNA-seq analysis of gene expression suggests a thyroid hormone-independent endocrine signaling pathway as the potential mechanism responsible for triggering the adaptive and corrective remodeling response in these larvae that involves and upregulation. Thus, investigating how malformed craniofacial tissues are naturally corrected in tadpoles has provided valuable insights into the maintenance and manipulation of craniofacial morphology in a vertebrate system. These insights may help in the development of novel therapies for developmental craniofacial anomalies in humans.