Combining different ion-selective channelrhodopsins to control water flux by light
Fei Lin, Ruijing Tang, Chong Zhang, Nicole Scholz, Georg Nagel, Shiqiang Gao
Abstract
Abstract Water transport through water channels, aquaporins (AQPs), is vital for many physiological processes including epithelial fluid secretion, cell migration and adipocyte metabolism. Water flux through AQPs is driven by the osmotic gradient that results from concentration differences of solutes including ions. Here, we developed a novel optogenetic toolkit that combines the light-gated anion channel Gt ACR1 either with the light-gated K + channel Hc KCR1 or the new Na + channelrhodopsin Hc NCR1 with high Na + permeability, to manipulate water transport in Xenopus oocytes non-invasively. Water efflux through AQP was achieved by light-activating K + and Cl - efflux through Hc KCR1 and Gt ACR1. Contrarily, when Gt ACR1 was co-expressed with Hc NCR1, inward movement of Na + and Cl - was light-triggered, and the resulting osmotic gradient led to water influx through AQP1. In sum, we demonstrate a novel optogenetic strategy to manipulate water movement into or out of Xenopus oocytes non-invasively. This approach provides a new avenue to interfere with water homeostasis as a means to study related biological phenomena across cell types and organisms.