Unveiling salivary gland-specific gene expression of Piezo1 and Neuroendocrine in the leech, Helobdella austinensis

Mechanotransduction is a critical biological phenomenon in living organisms, with Piezo1 being one of the key mechanotransduction ion channel genes. Piezo1 is widely expressed across various tissues and organs, playing critical roles in numerous biological processes, including innate and adaptive immune activation. While most studies on Neuroendocrine and Piezo functions have focused on vertebrates and higher invertebrates (e.g., Drosophila), however research in lophotrochozoan animal models remains scarce. To address this gap, we utilized Helobdella austinensis (phylum: Annelida) to investigate the putative function of Piezo1 and uncovered evidence related to the neuroendocrine system through spatiotemporal characterization. Our findings represent the developmental contribution of Piezo1 from early to late embryonic stages by demonstrating its expression in a lophotrochozoan. Intriguingly, the expression of Hau-Piezo1 was specifically detected in salivary gland-related precursors and tissues during development. Additionally, Neuroendocrine expression was observed in a lophotrochozoan, suggesting the correlation between neuronal stimulation and immune cells along the salivary glands of leeches. Furthermore, the downregulation of Hau-Piezo1 following bacterial challenge suggests that Piezo1 plays a role in regulating inflammatory responses. Taken together, we characterized the spatiotemporal expression pattern of Hau-Piezo1 in leeches and demonstrated its conserved and diversified functions based on its phylogenetic relationship with other homologs. These results suggest that Piezo1 may serve as a salivary gland marker in leeches and provide evidence for the presence of immune cells along the salivary glands in lophotrochozoans.