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Updated: Sep 25, 2026
Grafting of Beads into Developing Chicken Embryo Limbs to Identify Signal Transduction Pathways Affecting Gene Expression
Published on: January 17, 2016
Negative feedback regulation of FGF signaling levels by Pyst1/MKP3 in chick embryos
Maxwell C Eblaghie1, J Simon Lunn, Robin J Dickinson
1Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dow Street, United Kingdom.
Background:
The importance of endogenous antagonists in intracellular signal transduction pathways is becoming increasingly recognized. There is evidence in cultured mammalian cells that Pyst1/MKP3, a dual specificity protein phosphatase, specifically binds to and inactivates ERK1/2 mitogen-activated protein kinases (MAPKs). High-level Pyst1/Mkp3 expression has recently been found at many sites of known FGF signaling in mouse embryos, but the significance of this association and its function are not known.
Results:
We have cloned chicken Pyst1/Mkp3 and show that high-level expression in neural plate correlates with active MAPK. We show that FGF signaling regulates Pyst1 expression in developing neural plate and limb bud by ablating and/or transplanting tissue sources of FGFs and by applying FGF protein or a specific FGFR inhibitor (SU5402). We further show by applying a specific MAP kinase kinase inhibitor (PD184352) that Pyst1 expression is regulated via the MAPK cascade. Overexpression of Pyst1 in chick embryos reduces levels of activated MAPK in neural plate and alters its morphology and retards limb bud outgrowth.
Conclusions:
Pyst1 is an inducible antagonist of FGF signaling in embryos and acts in a negative feedback loop to regulate the activity of MAPK. Our results demonstrate both the importance of MAPK signaling in neural induction and limb bud outgrowth and the critical role played by dual specificity MAP kinase phosphatases in regulating developmental outcomes in vertebrates.
Insights
Pyst1 (protein tyrosine phosphatase 1) acts as an inducible antagonist of FGF signaling in developing embryos. This dual specificity MAP kinase phosphatase regulates MAPK activity through a negative feedback loop, impacting neural induction and limb development.
Area of Science:
- Developmental biology
- Molecular signaling
- Cellular regulation
Background:
- Endogenous antagonists play crucial roles in intracellular signal transduction.
- Pyst1/MKP3, a dual specificity protein phosphatase, inactivates ERK1/2 MAPKs.
- High Pyst1/Mkp3 expression is observed at FGF signaling sites in mouse embryos, but its function remains unclear.
Purpose of the Study:
- To investigate the function of Pyst1/Mkp3 in vertebrate embryonic development.
- To determine the relationship between Pyst1 expression, FGF signaling, and MAPK activity.
- To elucidate the role of Pyst1 in neural induction and limb development.
Main Methods:
- Cloned chicken Pyst1/Mkp3 and analyzed its expression in neural plate.
- Manipulated FGF signaling using tissue ablation/transplantation and FGF protein/FGFR inhibitor (SU5402).
- Investigated Pyst1 regulation via MAPK cascade using a MAP kinase kinase inhibitor (PD184352).
- Overexpressed Pyst1 in chick embryos to assess its effects on MAPK activity and embryonic morphology.
Main Results:
- High Pyst1/Mkp3 expression in the neural plate correlates with active MAPK.
- FGF signaling regulates Pyst1 expression in the developing neural plate and limb bud.
- Pyst1 expression is controlled by the MAPK cascade.
- Overexpression of Pyst1 reduces activated MAPK levels, alters neural plate morphology, and retards limb bud outgrowth.
Conclusions:
- Pyst1 functions as an inducible antagonist of FGF signaling in embryos.
- Pyst1 acts in a negative feedback loop to regulate MAPK activity.
- MAPK signaling is vital for neural induction and limb bud outgrowth.
- Dual specificity MAP kinase phosphatases are critical for vertebrate developmental outcomes.
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