Jagged-Notch signaling is involved in zebrafish notochord development

Mai Yamamoto1, Kunihiro Matsumoto2, Shigenomu Yonemura3, Koichi Kawakami4, and Motoyuki Itoh1

(IAR, Nagoya Univ.1, Div. Biol. Sci., Grad. Sch. Sci., Nagoya Univ.2, RIKEN, CDB3, NIG4)

  The Notch signaling pathway plays an important role in the determination of cell fate/differentiation in a number of organs. We found inhibition of Notch signaling led to morphological defect of notochord. As the notochord differentiates, a large vacuole is inflated within each cell and a peri-notochordal basement membrane is formed. Later, the notochord forms a metameric rod-shaped structure and functions as the skeleton of the developing embryos. Many studies have revealed its early patterning roles. However the mechanism by which the rod-like structure is formed and maintained is not fully understood. In Notch signaling deficient embryos such as mind bomb mutants, jaggedla/1b or su(H)morphants, notochord cells become vacuolated but have spherical instead of rod-like shape. Time-lapse analysis revealed notochord cells differentiate into two types of cells, vacuolated and non-vacuolated cells. We found that the number of vacuolated cell was increased, but non-vacuolated cells were decreased in Jagged-Notch signaling deficient embryos. In consistent with the reduction of non-vacuolated cells, peri-notochordal basement membrane which is presumably produced by non-vacuolated cells was less formed in Jagged-Notch signaling deficient embryos. Furthemore notochord cell specific activation of notch by GAL4-UAS system led to increased number of non-vaculated cells and reduction of vacuolated cells. Thus, our data suggest Notch controls commitment to a non-vacuolated cell fate to enable peri-notochordal basement formation required for notochord structural integrity.
Signaling in development, zebrafish, notch signaling, notochord