ZFIN ID: ZDB-PUB-171208-5
Nodal patterning without Lefty inhibitory feedback is functional but fragile
Rogers, K.W., Lord, N.D., Gagnon, J.A., Pauli, A., Zimmerman, S., Aksel, D.C., Reyon, D., Tsai, S.Q., Joung, J.K., Schier, A.F.
Date: 2017
Source: eLIFE   6: (Journal)
Registered Authors: Schier, Alexander, Zimmerman, Steve
Keywords: Lefty, Nodal, TGFβ, developmental biology, developmental patterning, feedback inhibition, mesendoderm, stem cells, zebrafish
MeSH Terms:
  • Animals
  • Endoderm/embryology*
  • Feedback*
  • Gene Knockout Techniques
  • Left-Right Determination Factors/genetics
  • Left-Right Determination Factors/metabolism*
  • Mesoderm/embryology*
  • Nodal Protein/metabolism*
  • Signal Transduction*
  • Zebrafish/embryology
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism*
PubMed: 29215332 Full text @ Elife
Developmental signaling pathways often activate their own inhibitors. Such inhibitory feedback has been suggested to restrict the spatial and temporal extent of signaling or mitigate signaling fluctuations, but these models are difficult to rigorously test. Here, we determine whether the ability of the mesendoderm inducer Nodal to activate its inhibitor Lefty is required for development. We find that zebrafish lefty mutants exhibit excess Nodal signaling and increased specification of mesendoderm, resulting in embryonic lethality. Strikingly, development can be fully restored without feedback: Lethal patterning defects in lefty mutants can be rescued by ectopic expression of lefty far from its normal expression domain or by spatially and temporally uniform exposure to a Nodal inhibitor drug. While drug-treated mutants are less tolerant of mild perturbations to Nodal signaling levels than wild type embryos, they can develop into healthy adults. These results indicate that patterning without inhibitory feedback is functional but fragile.