Inwardly rectifying potassium channels regulate Dpp release in the Drosophila wing disc

Abstract

Loss of embryonic ion channel function leads to morphological defects, but the underlying reason for these defects remains elusive. Here, we show that inwardly-rectifying potassium (Irk) channels regulate release of a Drosophila bone morphogenetic protein (BMP/Dpp) in the developing fly wing and this is necessary for developmental signaling. Inhibition of Irk channels decreases the incidence of distinct Dpp-GFP release events above baseline fluorescence while leading to broader distribution of Dpp-GFP. Work by others in different cell types show Irk channels regulate peptide release by modulating membrane potential and calcium levels. We found calcium transients in the developing wing and inhibition of Irk channels reduces the duration and amplitude of calcium transients. Depolarization with high extracellular potassium evokes Dpp release. Taken together, our data implicate Irk channels as a requirement for regulated release of Dpp, highlighting the importance of the temporal pattern of Dpp presentation for morphogenesis of the wing.