PgmNr Z6271: Syndecan4 facilitates FGF signaling in trailing cells and cell migration in the zebrafish lateral line primordium.

Authors:
C. M. Fox 1,2 ; A. B. Chitnis 1


Institutes
1) NICHD, Bethesda, MD; 2) Johns Hopkins University, Baltimore, MD.


Abstract:

The posterior lateral line (PLL), a sensory system that zebrafish use to sense water movement, is an extraordinarily tractable system in which to study cell migration and pattern formation. The posterior lateral line primordium (PLLP) spearheads the early development of this system, migrating from the ear to the tail, depositing rosettes of cells that will develop into mechanosensory neuromasts. Two signaling systems work in concert to achieve this pattern in the PLLP: Wnt signaling maintains a population of mesenchymal cells in the leading domain and fibroblast growth factor (FGF) signaling organizes cells into protoneuromasts in the trailing domain. Heparan sulfate proteoglycans (HSPGs), found in the extracellular matrix and on the cell surface, are known to regulate both Wnt and FGF signaling in a variety of developmental processes. Several core proteins for HSPGs are expressed within the PLLP and have been shown to be generally important for FGF signaling during PLLP migration. We show that the HSPG syndecan4 (SDC4) is expressed in the most trailing cells of the PLLP, where FGF signaling depends on a diminishing supply of FGF ligand. Knockdown of sdc4 interferes with protoneuromast formation, slows migration speed, and weakens FGF signaling output. Likewise, in sdc4 mutants with compromised FGF signaling, we observe slower migration. Overexpression of sdc4 induces dorsalization, a common effect of ectopic FGF signaling. Together, these results show that SDC4 maintains FGF signaling in the trailing cells of the PLLP, facilitating protoneuromast development and collective cell migration.



ZFIN Genetics Index
1. sdc4