Prolonged exposure to microgravity reduces cardiac contractility and initiates remodeling in Drosophila

Understanding the effects of long-term exposure to lower gravity environments on the human heart is important for exploring the Universe. Karen Occors and her collaborators used the advantages of the small size, well-defined and conserved genetics, of fruit flies (Drosophila melanogaster) to send them to the International Space Station in order to analyse the effects of microgravity on heart structure and function. Flies were born and raised for several weeks under microgravity before returning to earth gravity for analysis. In addition to wild-type flies, they examined the effect of microgravity on flies with mutations in seizure, the fly homolog of the human Kv11.1 protein, also referred to as ether-a-go-go-related gene (hERG). The human gene KCNH2 coding Kv11.1 is an alpha subunit of a potassium ion channel, which plays a critical role in cardiac action potential repolarisation. Mutations in KCNH2 are correlated to long QT syndrome (OMIM 613688). After functional, transcriptomic (RNAseq), and histological analyses, the authors conclude that exposure to microgravity causes significant heart dysfunction associated with changes in proteins that maintain heart structure and function.