Effects of voltage‐gated calcium channel subunit genes on calcium influx in cultured C. elegans mechanosensory neurons

• Published in: Journal of neurobiology 2006-09, Vol.66 (10), p.1125-1139
• Main Authors: Frøkjær‐Jensen, Christian, Kindt, Katie S., Kerr, Rex A., Suzuki, Hiroshi, Melnik‐Martinez, Katya, Gerstbreih, Beate, Driscol, Monica, Schafer, William R.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Animals, Genetically Modified; C. elegans; Caenorhabditis elegans; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Calcium - metabolism; calcium channel; Calcium Channels - genetics; Calcium Channels - metabolism; Cells, Cultured; genetics; Mechanoreceptors - cytology; Mechanoreceptors - physiology; mechanosensation; Molecular Sequence Data; Muscle Proteins - genetics; Muscle Proteins - metabolism; Mutation; neuroimaging; Neurons, Afferent - cytology; Neurons, Afferent - physiology; Protein Subunits - genetics; Protein Subunits - metabolism; Touch - physiology
• ISSN: 0022-3034; 1097-4695
• DOI: 10.1002/neu.20261

Voltage‐gated calcium channels (VGCCs) serve as a critical link between electrical signaling and diverse cellular processes in neurons. We have exploited recent advances in genetically encoded calcium sensors and in culture techniques to investigate how the VGCC α1 subunit EGL‐19 and α2/δ subunit UNC‐36 affect the functional properties of C. elegans mechanosensory neurons. Using the protein‐based optical indicator cameleon, we recorded calcium transients from cultured mechanosensory neurons in response to transient depolarization. We observed that in these cultured cells, calcium transients induced by extracellular potassium were significantly reduced by a reduction‐of‐function mutation in egl‐19 and significantly reduced by L‐type calcium channel inhibitors; thus, a main source of touch neuron calcium transients appeared to be influx of extracellular calcium through L‐type channels. Transients did not depend directly on intracellular calcium stores, although a store‐independent 2‐APB and gadolinium‐sensitive calcium flux was detected. The transients were also significantly reduced by mutations in unc‐36, which encodes the main neuronal α2/δ subunit in C. elegans. Interestingly, while egl‐19 mutations resulted in similar reductions in calcium influx at all stimulus strengths, unc‐36 mutations preferentially affected responses to smaller depolarizations. These experiments suggest a central role for EGL‐19 and UNC‐36 in excitability and functional activity of the mechanosensory neurons. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006