Not all cartilages are the same! Differential effects in the cranial vs caudal skeleton after BMP inhibition in zebrafish

Abstract

Several signaling factors are known to be involved in cartilage morphogenesis via the regulation of condensation size, shape, and location. Of these signaling factors, the bone morphogenetic proteins (BMPs) are known to be crucial in regulating the formation of condensations, cellular differentiation, and in the expression of the downstream transcription factors. Furthermore, interference with the BMP signaling pathway results in disrupted bone and cartilage development in various vertebrates. This study aims to elucidate the effects of BMP inhibition on cartilage morphology in the zebrafish. We utilise a pharmaceutical BMP pathway inhibitor at specific early time points of development. We focus on two cartilages, one cranial and one caudal, that develop concurrently but which have different developmental origins. Our data shows that the cranial cartilage, namely the scleral cartilage, is highly robust and unaffected by the BMP inhibitor. This is in stark contrast to the caudal cartilages, for example the hypurals, which are dramatically affected. These effects include fusion of elements, missing elements and altered morphology. Understanding these variable effects provides insight into the mechanisms that limit versus enable cartilages from altering their shape and/or size. The robustness of the cranial skeleton is particularly noteworthy given the multitude of disorders that affect this part of the skeleton.Support or Funding InformationFunding was provided by the Natural Science and Engineering Research Council of Canada