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Updated: Jun 22, 2026
Visualization of the Axonal Projection Pattern of Embryonic Motor Neurons in Drosophila
Published on: June 16, 2017
Drosophila multiplexin (Dmp) modulates motor axon pathfinding accuracy
Frauke Meyer1, Bernard Moussian
1Max-Planck-Institute for Developmental Biology, Department III - Genetics, Spemannstrasse 35, 72076 Tübingen, Germany.
Abstract:
Multiplexins are multidomain collagens typically composed of an N-terminal thrombospondin-related domain, an interrupted triple helix and a C-terminal endostatin domain. They feature a clear regulatory function in the development of different tissues, which is chiefly conveyed by the endostatin domain. This domain can be found in proteolytically released monomeric and trimeric versions, and their diverse and opposed effects on the migratory behavior of epithelial and endothelial cell types have been demonstrated in cell culture experiments. The only Drosophila multiplexin displays specific features of both vertebrate multiplexins, collagens XV and XVIII. We characterized the Drosophila multiplexin (dmp) gene and found that three main isoforms are expressed from it, one of which is the monomeric endostatin version. Generation of dmp deletion alleles revealed that Dmp plays a role in motor axon pathfinding, as the mutants exhibit ventral bypass defects of the intersegmental nerve b (ISNb) similar to other motor axon guidance mutants. Transgenic overexpression of monomeric endostatin as well as of full-length Dmp, but not trimeric endostatin, were able to rescue these defects. In contrast, trimeric endostatin increased axon pathfinding accuracy in wild type background. We conclude that Dmp plays a modulating role in motor axon pathfinding and may be part of a buffering system that functions to avoid innervation errors.
Insights
Drosophila multiplexin (dmp) influences motor axon pathfinding. Monomeric endostatin rescues defects, while trimeric endostatin enhances accuracy, suggesting a role in preventing innervation errors.
Area of Science:
- Developmental Biology
- Molecular Biology
- Neuroscience
Background:
- Multiplexins are multidomain collagens with regulatory roles in tissue development, primarily via their endostatin domain.
- The endostatin domain exists in monomeric and trimeric forms, exhibiting opposing effects on cell migration.
- The single Drosophila multiplexin (dmp) gene encodes isoforms with features of vertebrate collagens XV and XVIII.
Purpose of the Study:
- To characterize the Drosophila multiplexin (dmp) gene and its isoforms.
- To investigate the role of Dmp in motor axon pathfinding during Drosophila development.
- To determine the specific functions of different Dmp isoforms in axon guidance.
Main Methods:
- Gene characterization and isoform identification of Drosophila multiplexin (dmp).
- Generation of dmp deletion alleles to create mutant models.
- Transgenic overexpression of Dmp isoforms to assess rescue and enhancement effects on axon pathfinding.
Main Results:
- Three main dmp isoforms were identified, including a monomeric endostatin version.
- dmp deletion mutants displayed motor axon pathfinding defects, specifically ventral bypass defects in the intersegmental nerve b (ISNb).
- Overexpression of monomeric endostatin and full-length Dmp rescued these defects, while trimeric endostatin improved accuracy in wild-type backgrounds.
Conclusions:
- Drosophila multiplexin (dmp) plays a crucial role in modulating motor axon pathfinding.
- Different Dmp isoforms (monomeric vs. trimeric endostatin) have distinct functions in axon guidance.
- Dmp may function within a buffering system to prevent motor innervation errors.
