Hippo and Wnt as Early Initiators: Integrated Multi-Omics Reveals the Signaling Basis for Corona-Induced Diapause Termination in Silkworm

TL;DR

This study identifies the Hippo and Wnt signaling pathways as early initiators in breaking developmental arrest in silkworm eggs after corona treatment, offering new insights for improving silk production.

Contribution

The study reveals Hippo and Wnt pathways as the earliest molecular responders to corona treatment, preceding the previously known FoxO pathway in diapause termination.

Findings

Hippo and Wnt signaling pathways are activated within 1 hour of corona treatment in silkworm eggs.

The Hippo pathway includes immediate-early genes and late-phase effector genes coordinating cell cycle re-entry.

The Wnt pathway is rapidly initiated with sustained upregulation of Notum and Pontin52, promoting developmental resumption.

Abstract

Embryonic diapause in silkworm eggs is a state of developmental arrest that challenges year-round silk production. Although physical treatments such as corona discharge can break diapause, the early molecular events remain unclear. In this study, we used transcriptomic and proteomic approaches to analyze silkworm eggs within 48 h after corona treatment. We found that the Hippo and Wnt signaling pathways are activated as early as 1 h post-treatment, earlier than the previously reported FoxO pathway. These pathways appear to coordinate cell cycle re-entry and developmental resumption. Our findings suggest that Hippo and Wnt act as initial responders in converting a physical stimulus into a developmental signal, offering new insights for improving silkworm breeding efficiency.

Embryonic diapause, a state of developmental arrest in silkworm (Bombyx mori) eggs, poses a challenge for year-round sericulture. While physical stimuli like corona discharge can effectively terminate diapause, the underlying molecular mechanisms, particularly the initial events, remain poorly understood. This study employed an integrated transcriptomic and proteomic approach to analyze silkworm eggs within 48 h after corona treatment. Our time-series analysis revealed that the Hippo and Wnt signaling pathways were specifically activated as early as 1 h post-treatment, preceding the previously reported FoxO pathway response. We identified two temporally distinct gene clusters within the Hippo pathway, including immediate–early genes (e.g., Dachs_17/25/29, Ft_10) and late-phase effector genes, coordinating the exit from cell cycle arrest. Concurrently, the Wnt pathway was rapidly initiated, marked by the sustained upregulation of key regulators Notum and Pontin52, suggesting its role in unlocking the cell cycle. We propose a synergistic model wherein corona discharge triggers the concurrent, early activation of Hippo and Wnt signaling, which collectively reprogram the cell cycle and reinstate the developmental trajectory by promoting proliferation and suppressing apoptosis. These findings provide crucial insights into the initial molecular events of diapause termination, identifying Hippo and Wnt pathways as master regulators in transducing the physical corona stimulus into a developmental signal.

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