Investigating the molecular mechanism of Wnt5b and Wntless-mediated zebrafish jaw cartilage development
Date Issued
2015
Date
2015
Author(s)
Wu, Bo-Tsung
Abstract
Secreted Wnt molecules play a pivotal role in cell-cell communications during the development of multicellular organisms. The transmembrane protein Wntless (Wls) is one of the few proteins that are identified to control the secretion of active Wnt signaling. Although loss of Wnt signaling resulted in diverse developmental defects during zebrafish embryonic development, loss of maternal or zygotic Wls activity in embryos caused no obvious collective loss-of-Wnt phenotypes, suggesting that Wls exists selectivity on different Wnt molecules during zebrafish embryonic development. To date, Wnts and Fgfs have been reported to regulate various tissues development, but relatively little is known about how regional Wnt or Fgf activities are established and how they interact in any given developmental event. Here, I have investigated the Wnt-mediated craniofacial cartilage development in zebrafish and found that fgf3 expression is down-regulated in wls mutants and wls morpholino (MO)-injected embryos (morphants) and in wnt5b mutants, but no fgf3 expression alternation is observed in wnt9a and wnt11 morphants. In addition, introducing full-length fgf3 mRNAs but not fgf8 can rescue the Wls or Wnt5b deficiency-induced jaw cartilage defects. Immuno-histochemical staining also revealed that endogenous Wnt5b, but not Wnt11, required Wls for its secretion during the jaw development at 48 hpf in zebrafish embryos, indicating that Wls is not involved in every Wnt secretion events in zebrafish cells. Moreover, cell proliferation was affected while apoptosis was normal in the developing jaw of wls morphants. Together, Wnt5b requires Wls for secretion and regulates the proliferation of chondrogenic cells through fine-tuning the expression of fgf3 during embryonic jaw cartilage development.
Subjects
zebrafish
Wntless
Fgf3
Wnt5b
jaw cartilage
Type
thesis
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