Related Experiment Videos
Chick RGS2L demonstrates concentration-dependent selectivity for pertussis toxin-sensitive and -insensitive pathways
Patrizia Tosetti1, Valeria Parente, Vanni Taglietti
1Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA.
Abstract:
In neuronal cells, the influx of Ca2+ ions through voltage-dependent L-type calcium (L) channels couples excitation to multiple cellular functions. In addition to voltage, several neurotransmitters, hormones and cytokines regulate L channel gating via binding to G-protein-coupled receptors. Intracellular molecules that modify G-protein activity - such as regulator of G-protein-signalling (RGS) proteins - are therefore potential candidates for regulating Ca2+ influx through L channels. Here we show that a novel RGS2 splice variant from chick dorsal root ganglion (DRG) neurons, RGS2L, reduces bradykinin (BK)-mediated inhibition of neuronal L channels and accelerates recovery from inhibition. Chick RGS2 reduces the inhibition mediated by both the pertussis toxin (PTX)-sensitive (Gi/o-coupled) and the PTX-insensitive (presumably Gq/11-coupled) pathways. However, we demonstrate for the first time in a living cell that the extent of coupling to each pathway varies with RGS2L concentration. A low concentration of recombinant chick RGS2L (10 nM) preferentially reduces the inhibition mediated by the PTX-insensitive pathway, whereas a 100-fold higher concentration attenuates both PTX-sensitive- and PTX-insensitive-mediated components equally. Our data suggest that factors promoting RGS2L gene induction may regulate Ca2+ influx through L channels by recruiting low-affinity interactions with Gi/o that are absent at basal RGS2L levels.
Insights
A novel RGS2L protein variant in neurons modulates calcium channel activity. RGS2L affects bradykinin-induced inhibition of L-type calcium channels, with concentration-dependent effects on signaling pathways.
Area of Science:
- Neuroscience
- Molecular Biology
- Cellular Physiology
Background:
- Neuronal calcium influx via L-type calcium channels is crucial for cellular functions.
- G-protein-coupled receptors and intracellular regulators like RGS proteins modulate channel activity.
- RGS proteins are potential regulators of calcium influx through L-type channels.
Purpose of the Study:
- To investigate the role of a novel RGS2 splice variant, RGS2L, in regulating neuronal L-type calcium channels.
- To determine how RGS2L affects bradykinin-mediated inhibition of these channels.
- To elucidate the concentration-dependent effects of RGS2L on different G-protein signaling pathways.
Main Methods:
- Utilized chick dorsal root ganglion (DRG) neurons.
- Investigated a novel RGS2 splice variant, RGS2L.
- Assessed bradykinin (BK)-mediated inhibition of neuronal L-type calcium channels.
- Examined effects of varying recombinant chick RGS2L concentrations (10 nM and 1000 nM).
- Differentiated between pertussis toxin (PTX)-sensitive (Gi/o) and PTX-insensitive (Gq/11) pathways.
Main Results:
- RGS2L reduces bradykinin-mediated inhibition of neuronal L-type calcium channels and accelerates recovery.
- Chick RGS2 affects inhibition mediated by both PTX-sensitive and PTX-insensitive pathways.
- Low RGS2L concentration (10 nM) preferentially reduces PTX-insensitive pathway inhibition.
- High RGS2L concentration (1000 nM) equally attenuates both PTX-sensitive and PTX-insensitive pathway inhibition.
Conclusions:
- RGS2L plays a significant role in modulating neuronal L-type calcium channel activity.
- The concentration of RGS2L dictates its interaction with different G-protein signaling pathways.
- Gene induction of RGS2L may regulate calcium influx by influencing interactions with Gi/o proteins.