The Shape of the Jaw-Zebrafish Col11a1a Regulates Meckel's Cartilage Morphogenesis and Mineralization

The expression of the col11a1a gene is essential for normal skeletal development, affecting both cartilage and bone. Loss of function mutations have been shown to cause abnormalities in the growth plate of long bones, as well as in craniofacial development. However, the specific effects on Meckel's cartilage have not been well studied. To further understand the effect of col11a1a gene function, we analyzed the developing jaw in zebrafish using gene knockdown by the injection of an antisense morpholino oligonucleotide using transgenic Tg(sp7:EGFP) and Tg(Fli1a:EGFP) EGFP reporter fish, as well as wildtype AB zebrafish. Our results demonstrate that zebrafish col11a1a knockdown impairs the cellular organization of Meckel's cartilage in the developing jaw and alters the bone formation that occurs adjacent to the Meckel's cartilage. These results suggest roles for Col11a1a protein in cartilage intermediates of bone development, the subsequent mineralization of the bony collar of long bones, and that which occurs adjacent to Meckel's cartilage in the developing jaw.