title: The Drosophila SK channel (dSK) contributes to photoreceptor performance by mediating sensitivity control at the first visual network.
abstract: The contribution of the SK (small-conductance calcium-activated potassium) channel to neuronal functions in complex circuits underlying sensory processing and behavior is largely unknown in the absence of suitable animal models. Here, we generated a Drosophila line that lacks the single highly conserved SK gene in its genome (dSK). In R1-R6 photoreceptors, dSK encodes a slow Ca²⁺-activated K(+) current similar to its mammalian counterparts. Compared with wild-type, dSK(-) photoreceptors and interneurons showed accelerated oscillatory responses and adaptation. These enhanced kinetics were accompanied with more depolarized dSK(-) photoreceptors axons, assigning a role for dSK in network gain control during light-to-dark transitions. However, compensatory network adaptation, through increasing activity between synaptic neighbors, overcame many detriments of missing dSK current enabling dSK(-) photoreceptors to maintain normal information transfer rates to naturalistic stimuli. While demonstrating important functional roles for dSK channel in the visual circuitry, these results also clarify how homeostatically balanced network functions can compensate missing or faulty ion channels.
authors.affiliation: Department of Biology, Dartmouth College, Hanover, New Hampshire 03755, USA.
authors.forename: Ahmad N
authors.initials: AN
authors.lastname: Abou Tayoun
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Li
authors.forename: Brian
authors.initials: B
authors.lastname: Chu
authors.forename: Roger C
authors.initials: RC
authors.lastname: Hardie
authors.forename: Mikko
authors.initials: M
authors.lastname: Juusola
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Dolph
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology*; D004331:Drosophila melanogaster; D005260:Female; D008297:Male; D008969:Molecular Sequence Data; D009415:Nerve Net / Q000502:physiology*; D010786:Photoreceptor Cells / Q000502:physiology*; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000235:genetics / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*
chemical_list: D029721:Drosophila Proteins; D051640:Small-Conductance Calcium-Activated Potassium Channels