Fig. 8

Model for how Crocc2 may influence cartilage morphogenesis and growth. At the protein level, wild-type Crocc2 dimerizes and self-assembles into elongated striated filaments (Step 1)62, 64 that can play distinct roles within the cell. (Step 2) As the major constituent of ciliary rootlets, Crocc2 is necessary for rootlet structure(s),60-62 which extend proximally from the base of a cilium toward subcellular organelles and structures inside the cell, including the nucleus.56-58, 60, 62 (Step 3) We propose that cilia in cartilage cells receive mechanical stimulation from muscles and ligament insertion sites, and that Crocc2 in the rootlets plays a role in mechanotransduction,66 leading to proper columnar cell shapes (light blue) and directional orientation of PCP (red ovals) within the developing cartilage. (Step 4) Across the entire pharyngeal skeleton, we propose that these mechanisms are required for proper geometry and canalized growth.