Modeling PIEZO associated diseases in Caenorhabditis elegans: from genetics to mechanism

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 skillset and facilitate
my transition into an independent researcher in the field of genetics, development, mechanobiology, and
translational science of human rare diseases.

Grant Number: 5R00GM145224-04
NIH Institute/Center: NIH
Principal Investigator: Xiaofei Bai