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Swimming Induced Paralysis to Assess Dopamine Signaling in Caenorhabditis elegans
Published on: April 3, 2019
Regulation of dopamine release by CASK-β modulates locomotor initiation in Drosophila melanogaster
Justin B Slawson1, Elena A Kuklin1, Konark Mukherjee1
1Department of Biology, Volen Center for Complex Systems, National Center for Behavioral Genomics, Brandeis University Waltham, MA, USA.
Abstract:
CASK is an evolutionarily conserved scaffolding protein that has roles in many cell types. In Drosophila, loss of the entire CASK gene or just the CASK-β transcript causes a complex set of adult locomotor defects. In this study, we show that the motor initiation component of this phenotype is due to loss of CASK-β in dopaminergic neurons and can be specifically rescued by expression of CASK-β within this subset of neurons. Functional imaging demonstrates that mutation of CASK-β disrupts coupling of neuronal activity to vesicle fusion. Consistent with this, locomotor initiation can be rescued by artificially driving activity in dopaminergic neurons. The molecular mechanism underlying this role of CASK-β in dopaminergic neurons involves interaction with Hsc70-4, a molecular chaperone previously shown to regulate calcium-dependent vesicle fusion. These data suggest that there is a novel CASK-β-dependent regulatory complex in dopaminergic neurons that serves to link activity and neurotransmitter release.
Insights
Loss of CASK-β in fruit fly dopaminergic neurons impairs motor initiation. Restoring CASK-β or neuronal activity rescues this defect, revealing a novel pathway linking neuronal activity to neurotransmitter release.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Calcium/calmodulin-dependent serine protein kinase (CASK) is a conserved scaffolding protein with diverse cellular functions.
- Loss of CASK or its CASK-β transcript in Drosophila leads to complex adult locomotor defects.
- Dopaminergic neurons are crucial for motor control and initiation.
Purpose of the Study:
- To investigate the specific role of CASK-β in dopaminergic neurons concerning locomotor defects in Drosophila.
- To elucidate the molecular mechanisms by which CASK-β influences neuronal function and neurotransmitter release.
Main Methods:
- Genetic manipulation in Drosophila to specifically alter CASK-β expression in dopaminergic neurons.
- Behavioral assays to assess locomotor initiation.
- Functional imaging techniques to analyze neuronal activity and vesicle fusion.
- Co-immunoprecipitation assays to identify protein interactions.
Main Results:
- Loss of CASK-β in dopaminergic neurons specifically causes impaired motor initiation.
- Re-expression of CASK-β in these neurons rescues the locomotor defect.
- CASK-β is essential for coupling neuronal activity to vesicle fusion, and its absence disrupts this process.
- CASK-β interacts with the molecular chaperone Hsc70-4, suggesting a role in regulating vesicle fusion.
Conclusions:
- CASK-β plays a critical, cell-autonomous role in dopaminergic neurons for initiating locomotion in Drosophila.
- A novel CASK-β-dependent regulatory complex involving Hsc70-4 links neuronal activity to neurotransmitter release.
- These findings provide new insights into the molecular basis of motor control and neurotransmission.
