Divergent requirements for fibroblast growth factor signaling in zebrafish maxillary barbel and caudal fin regeneration. (28th January 2013)

• Record Type: Journal Article
• Authors: Duszynski, Robert J.; Topczewski, Jacek; LeClair, Elizabeth E.
• Is Part Of: Development growth and differentiation. Volume 55:Number 2(2013)
• Page Start: 282
• Page End: 300
• Publication Date: 2013-01-28
• Subjects: Embryology -- Periodicals; Developmental biology -- Periodicals; Growth -- Periodicals; 574.3
• DOI: 10.1111/dgd.12035
• Languages: English
• ISSNs: 0012-1592

Abstract

<abstract abstract-type="main" id="dgd12035-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>The zebrafish maxillary barbel is an integumentary organ containing skin, glands, pigment cells, taste buds, nerves, and endothelial vessels. The maxillary barbel can regenerate (LeClair & Topczewski 2010); however, little is known about its molecular regulation. We have studied fibroblast growth factor (FGF) pathway molecules during barbel regeneration, comparing this system to a well‐known regenerating appendage, the zebrafish caudal fin. Multiple FGF ligands (<italic>fgf20a, fgf24</italic>), receptors (<italic>fgfr1‐4</italic>) and downstream targets (<italic>pea3, il17d</italic>) are expressed in normal and regenerating barbel tissue, confirming FGF activation. To test if specific FGF pathways were required for barbel regeneration, we performed simultaneous barbel and caudal fin amputations in two temperature‐dependent zebrafish lines. Zebrafish homozygous for a point mutation in <italic>fgf20a</italic>, a factor essential for caudal fin blastema formation, regrew maxillary barbels normally, indicating that the requirement for this ligand is appendage‐specific. Global overexpression of a dominant negative FGF receptor, <italic>Tg(hsp70l:dn‐fgfr1:EGFP</italic>)<sup><italic>pd1</italic></sup> completely blocked fin outgrowth but only partially inhibited barbel outgrowth, suggesting reduced requirements for FGFs in barbel tissue. Maxillary barbels expressing <italic>dn‐fgfr1</italic> regenerated peripheral nerves, dermal connective tissue, endothelial tubes, and a glandular epithelium; in contrast to a recent report in which <italic>dn‐fgfr1</italic> overexpression blocks pharyngeal taste bud formation in zebrafish larvae (Kapsimali <italic>et al</italic>. 2011), we observed robust formation of calretinin‐positive tastebuds. These are the first experiments to explore the molecular mechanisms of maxillary barbel regeneration. Our results suggest heterogeneous requirements for FGF signaling in the regeneration of different zebrafish appendages (caudal fin versus maxillary barbel) and taste buds of different embryonic origin (pharyngeal endoderm versus barbel ectoderm).</p> </abstract>