Yamamoto, M., Morita, R., Mizoguchi, T., Matsuo, H., Isoda, M., Ishitani, T., Chitnis, A.B., Matsumoto, K., Crump, J.G., Hozumi, K., Yonemura, S., Kawakami, K., and Itoh, M. (2010) Mib-Jag1-Notch signalling regulates patterning and structural roles of the notochord by controlling cell-fate decisions. Development (Cambridge, England). 137(15):2527-2537.
In the developing embryo, cell-cell signalling is necessary for tissue patterning and structural organization. During midline development, the notochord plays roles in the patterning of its surrounding tissues while forming the axial structure; however, how these patterning and structural roles are coordinated remains elusive. Here, we identify a mechanism by which Notch signalling regulates the patterning activities and structural integrity of the notochord. We found that Mind bomb (Mib) ubiquitylates Jagged 1 (Jag1) and is essential in the signal-emitting cells for Jag1 to activate Notch signalling. In zebrafish, loss- and gain-of-function analyses showed that Mib-Jag1-Notch signalling favours the development of non-vacuolated cells at the expense of vacuolated cells in the notochord. This leads to changes in the peri-notochordal basement membrane formation and patterning surrounding the muscle pioneer cells. These data reveal a previously unrecognized mechanism regulating the patterning and structural roles of the notochord by Mib-Jag1-Notch signalling-mediated cell-fate determination.