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The Ras1-mitogen-activated protein kinase signal transduction pathway regulates synaptic plasticity through fasciclin
Young-Ho Koh1, Catalina Ruiz-Canada, Michael Gorczyca
1Department of Biology, Neuroscience and Behavior Program, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Abstract:
Ras proteins are small GTPases with well known functions in cell proliferation and differentiation. In these processes, they play key roles as molecular switches that can trigger distinct signal transduction pathways, such as the mitogen-activated protein kinase (MAPK) pathway, the phosphoinositide-3 kinase pathway, and the Ral-guanine nucleotide dissociation stimulator pathway. Several studies have implicated Ras proteins in the development and function of synapses, but the molecular mechanisms for this regulation are poorly understood. Here, we demonstrate that the Ras-MAPK pathway is involved in synaptic plasticity at the Drosophila larval neuromuscular junction. Both Ras1 and MAPK are expressed at the neuromuscular junction, and modification of their activity levels results in an altered number of synaptic boutons. Gain- or loss-of-function mutations in Ras1 and MAPK reveal that regulation of synapse structure by this signal transduction pathway is dependent on fasciclin II localization at synaptic boutons. These results provide evidence for a Ras-dependent signaling cascade that regulates fasciclin II-mediated cell adhesion at synaptic terminals during synapse growth.
Insights
Ras proteins and the MAPK pathway regulate synapse structure by controlling cell adhesion molecule localization at the Drosophila neuromuscular junction, impacting synapse growth.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- Ras proteins are GTPases crucial for cell signaling, proliferation, and differentiation.
- Ras proteins act as molecular switches, activating pathways like MAPK, PI3K, and RalGDS.
- While implicated in synapse development, Ras protein mechanisms in synaptic regulation remain unclear.
Purpose of the Study:
- To investigate the role of the Ras-MAPK pathway in synaptic plasticity.
- To elucidate the molecular mechanisms linking Ras signaling to synapse structure and function.
Main Methods:
- Utilized Drosophila larval neuromuscular junction as a model system.
- Employed gain- and loss-of-function mutations for Ras1 and MAPK.
- Assessed the impact on synaptic bouton number and fasciclin II localization.
Main Results:
- Ras1 and MAPK are expressed at the Drosophila neuromuscular junction.
- Modulating Ras1 and MAPK activity altered synaptic bouton numbers.
- Synapse structure regulation by Ras-MAPK depends on fasciclin II localization.
Conclusions:
- The Ras-MAPK pathway is integral to synaptic plasticity at the Drosophila neuromuscular junction.
- This signaling cascade regulates fasciclin II-mediated cell adhesion at synaptic terminals.
- Provides mechanistic insight into Ras-dependent regulation of synapse growth.