Pharmacological Intervention of PIEZO1 for Butterfly Eyespot Color Patterns in Junonia orithya

Background: PIEZO channels are mechanoreceptors expressed in various cells. Their contributions to animal development are not entirely clear. According to the physical distortion hypothesis, developmental organizers for butterfly wing eyespots receive and release mechanical signals in pupal wing tissues during development, initiating a calcium signaling cascade and gene expression changes. Objectives: We tested the possible involvement of PIEZO1 in butterfly wing color pattern formation, according to the physical distortion hypothesis. Methods: We performed a pharmacological intervention of PIEZO1, focusing on the eyespots of Junonia orithya. Chemical modulators of PIEZO1 and the actin cytoskeleton were injected into pupae immediately after pupation during the critical period of color pattern determination, and the eyespot color patterns of the emerging adult wings were analyzed. We also tested dimethyl sulfoxide (DMSO) because it was used as a solvent. Results: DMSO significantly enlarged most eyespots examined. In contrast, the specific PIEZO1 activator Jedi2 induced significant reduction in the dorsal hindwing eyespots. Another specific PIEZO1 activator, Yoda1, also induced similar changes, although less clearly. The mechanosensitive channel blocker GsMTx4 produced compromised eyespots in an individual, although statistical support for modification was weak. The actin polymerization activator phalloidin induced blue foci in the ventral forewing eyespots. PIEZO expression in the pupal wings was demonstrated by RT-PCR. Conclusions: These results suggest that eyespot organizers in butterfly wings may employ a PIEZO-mediated mechanotransduction pathway to regulate eyespot color patterns, supporting the physical distortion hypothesis. These results highlight the importance of PIEZO in developmental organizers in animals.