ZFIN ID: ZDB-PUB-021017-58
Dual roles for FGF signaling in promoting zebrafish hindbrain development
Maves, L. and Kimmel, C.B.
The segmentation of the vertebrate hindbrain into rhombomeres is highly conserved, but how early hindbrain patterning is established is not well understood. We have found that rhombomere 4 (r4) is an early-differentiating rhombomere that functions as an organizing center in the middle of the zebrafish hindbrain. Two fibroblast growth factor (FGF) signals, FGF3 and FGF8, are expressed early in r4 and are together required for the development of r5 and r6. Transplantation of r4 cells can induce expression of early r5/r6 markers, demonstrating that r4 tissue has organizing activity. Misexpression of FGF3 or FGF8 can also induce expression of r5/r6 markers, showing that FGF signals mediate the organizing activity of r4. These findings underscore the significance of organizing centers in patterning the vertebrate neural plate. Additionally, FGF3 plays an earlier role in hindbrain development by promoting
posteriorization of the neuroectoderm during gastrulation. FGF3 signaling from mesendoderm promotes expression of hindbrain markers. In particular, misexpression of FGF3 in anterior mesendoderm is sufficient to posteriorize the forebrain and thus likely mediates the posteriorizing activity previously attributed to nonaxial mesendoderm. Our findings thus support dual, sequential roles of FGF signaling in promoting hindbrain development.
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