An Fgf-Shh positive feedback loop drives growth in developing unpaired fins

M. Brent Hawkins, David Jandzik, Frank J. Tulenko, Amanda N. Cass, Tetsuya Nakamura, Neil H. Shubin, Marcus C. Davis, David W. Stock

Research output: Contribution to journalArticlepeer-review


The origin and diversification of appendage types is a central question in vertebrate evolution. Understanding the genetic mechanisms that underlie fin and limb development can reveal relationships between different appendages. Here we demonstrate, using chemical genetics, a mutually agonistic interaction between Fgf and Shh genes in the developing dorsal fin of the channel catfish, Ictalurus punctatus. We also find that Fgf8 and Shh orthologs are expressed in the apical ectodermal ridge and zone of polarizing activity, respectively, in the median fins of representatives from other major vertebrate lineages. These findings demonstrate the importance of this feedback loop in median fins and offer developmental evidence for a median fin-first scenario for vertebrate paired appendage origins.

Original languageEnglish (US)
Article numbere2120150119
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number10
StatePublished - Mar 8 2022

All Science Journal Classification (ASJC) codes

  • General


  • Evolutionary developmental biology
  • Fibroblast growth factor signaling
  • Hedgehog signaling
  • Median fin
  • Unpaired fin


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