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Dpp gradient formation by dynamin-dependent endocytosis: receptor trafficking and the diffusion model
Karsten Kruse1, Periklis Pantazis, Tobias Bollenbach
1MPI for the Physics of Complex Systems, Nöthnitzerstrasse 38, 01187 Dresden, Germany.
Development (Cambridge, England)
|September 11, 2004
Summary
Morphogen gradients, crucial for cell development, are not solely explained by extracellular diffusion. Dynamin-dependent endocytosis plays a key role in morphogen spreading, challenging existing models.
Area of Science:
- Developmental Biology
- Cell Biology
- Biophysics
Background:
- Cellular positional information relies on morphogen gradients.
- In Drosophila, Decapentaplegic (Dpp) morphogen forms gradients essential for wing development.
- Current models assume Dpp spreads via extracellular diffusion, with endocytosis primarily downregulating cell surface receptors.
Purpose of the Study:
- To investigate the role of endocytosis in Dpp morphogen spreading.
- To theoretically model morphogen spreading incorporating receptor binding and trafficking.
- To compare model predictions with experimental data on Dpp and receptor distribution.
Main Methods:
- Theoretical modeling of morphogen spreading.
- Incorporation of receptor binding and endocytic trafficking into diffusion models.
- Experimental monitoring of extracellular Dpp and cell surface receptors using antibodies.
Main Results:
- Pure extracellular diffusion models fail to explain Dpp spreading dynamics.
- Dynamin-dependent endocytosis is implicated in mediating Dpp movement.
- Model simulations incorporating endocytosis align better with experimental observations.
Conclusions:
- Extracellular diffusion alone is insufficient to account for long-range morphogen spreading.
- Endocytosis actively participates in morphogen dispersal, not just receptor downregulation.
- Rethinking morphogen gradient formation models is necessary to include active endocytic mechanisms.