Project Summary/ Abstract Channelopathies are diseases or physiological disorders caused by the dysfunctional ion channel proteins. For example, the essential mechanosensitive channels PIEZO1 and PIEZO2 have been tightly linked to multiple diseases, such as distal arthrogryposis, dehydrated hereditary stomatocytosis, and Gordon Syndrome. There are ~100 disease alleles that have been identified in PIEZO1/2, most of which caused severe physiological disorders in cardiovascular, vestibular, neuronal, and connective tissues. Despite the electrophysiological studies in the patients’ cells indicated that these symptoms are likely due to a mechanotransduction defect, the underlying mechanisms or molecular determinants of PIEZO diseases remain largely unknown. Here, I introduce a facile and powerful in vivo system for the functional study of PIEZO; the stretch sensitive and responsive C. elegans reproductive tract. I have discovered that the dysfunctional PEZO-1 (the sole ortholog of PIEZO in C. elegans) causes severely reduced brood sizes due to the crushing oocytes in the spermatheca and poor sperm motility (3). This proposed study aims to discover the nature of the pathways and genetic interactors that enable PIEZO to respond to mechanical stimuli and coordinate mechanotransductive tissue function in vivo. Furthermore, I will identify new genetic suppressors and associated pathways in the C. elegans reproductive tract. This basic research will shed light on the understanding of channelopathy diseases caused by PIEZO dysfunction and the potential therapeutical drug target design. To achieve these goals, I will pursue three specific aims: The first aim is to identify novel genetic interactors of PEZO-1 in C. elegans. A combination of genetic screens and biochemical assays will be used to achieve this aim. I expect that completing the proposed aims will establish the C. elegans reproductive system as a simple and genetically tractable model to elucidate PIEZO biological functions and to better understand the molecular mechanisms of PEZO-1 activity. The second aim is to determine whether inter-tissue signaling pathways (such as the sex hormone prostaglandin) is affected in pezo-1 mutants. To achieve this aim, I will perform genetic and biochemical assays to determine whether PEZO-1 contributes to prostaglandin synthesis and secretion, which are essential for sperm attraction. The final aim is to identify target tissues and relative contribution of PIEZO disease alleles to intracellular Ca2+ homeostasis and signaling. To achieve this aim, I will generate a set of the tissue-specific Ca2+ indicators to quantify the calcium influx in each mutant. These studies should lead to a comprehensive delineation of genes that interact with pezo-1, and new pathways that involve mechanotransduction. This research will also shed light on the molecular mechanisms of the genetic diseases caused by PIEZO dysfunction. Overall, this K99/R00 award will strengthen my research s...