Complementation of Physiological and Behavioral Defects by a Slowpoke Ca²⁺ ‐Activated K⁺ Channel Transgene

Abstract

Abstract:The Drosophila slowpoke gene encodes a large conductance calcium-activated potassium channel used in neurons, muscle, and some epithelial cells. Tissuespecific transcriptional promoters and alternative mRNA splicing generate a large array of transcripts. These distinct transcripts are thought to tailor the properties of the channel to the requirements of the cell. Presumably, a single splice variant cannot satisfy the specific needs of all cell types. To test this, we examined whether a single slowpoke splice variant was capable of complementing all slowpoke behavioral phenotypes. Null mutations in slowpoke cause animals to be semiflightless and to manifest an inducible "sticky-feet" phenotype. The well-characterized slowpoke transcriptional control region was used to direct the expression of a single slowpoke splice variant (cDNA H13) in transgenic flies. The endogenous gene in these flies had been inactivated by the slo 4 mutation. Action-potential recordings and voltage-clamp recordings demonstrated the production of functional channels from the transgene. The transgene completely complemented the flight defect, but not the sticky-feet phenotype. We conclude that distinct slowpoke channel isoforms, produced by alternative splicing, are not interchangeable and are required for proper function of different cell types. Key Words: Potassium channel-slowpoke-Drosophila-mRNA splicing-Behavior-Voltage clamp.

Cell Excitability Necessary for Male Mating Behavior inCaenorhabditis elegansIs Coordinated by Interactions Between Big Current and Ether-A-Go-Go Family K+ Channels

“…RCK sites are proposed to mediate calcium's gating of the channel (Lee and Cui 2010;Yuan et al 2010), a modification that is common across species (Fodor and Aldrich 2009). Similarly, isoform-specific rescue of flight was shown in Drosophila (Brenner et al 2000). Across different species, age, cell type, and stress impact which isoforms of slo-1 are expressed (Tseng-Crank et al 1994;Xie and McCobb 1998;MacDonald et al 2006;Kim et al 2010).…”

Effects of manipulating slowpoke calcium-dependent potassium channel expression on rhythmic locomotor activity inDrosophilalarvae

“…Channels encoded by the slo gene carry transient I KCa in muscles (Elkins, Ganetzky & Wu, 1986; Komatsu et al, 1990; Singh & Wu, 1989), and both transient and sustained I KCa in neurons (Saito & Wu, 1991). slo mutations in Drosophila cause action potential broadening (Atkinson et al, 1998; Brenner et al, 2000; Elkins & Ganetzky, 1988; Elkins, Ganetzky & Wu, 1986; Saito & Wu, 1991), decreased delay to first spike (Elkins & Ganetzky, 1988; Elkins, Ganetzky & Wu, 1986), increased interspike interval (Elkins & Ganetzky, 1988), changes in firing patterns that include “abnormal regenerative responses” (Saito & Wu, 1991; Singh & Wu, 1990), delayed repolarization of the neuromuscular junction (Gho & Ganetzky, 1992), and reduced synaptic transmission (Lee, Ueda & Wu, 2008; Warbington et al, 1996). Locomotor deficits are observed in adult slo mutants, including shaking under ether anesthesia, reduced flight, semi-paralysis in response to heat or bright light (Atkinson et al, 1998; Atkinson et al, 2000; Elkins, Ganetzky & Wu, 1986), and abnormal circadian patterns of activity (Ceriani et al, 2002; Fernández et al, 2007).…”

Impaired clock output by altered connectivity in the circadian network

“…A null mutation in the slo locus strikingly alters the electrical properties of both neurons and muscles (22)(23)(24), affecting neurotransmitter release (25) and thereby causing a variety of behavioral defects among those in courtship behavior (26)(27)(28). We have previously demonstrated that a slo null mutant is behaviorally arrhythmic under free-running [constant darkness (DD)] conditions (13).…”