W4-03

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