Hedgehog signaling regulates regenerative patterning and growth inHarmonia axyridisleg

Appendage regeneration has been widely studied in many species. Compared to other animal models,Harmonia axyridishas the advantage of a short life cycle, is easily reared, has strong regeneration capacity and contains systemic RNAi, making it a model organism for research on appendage regeneration. Here, we performed transcriptome analysis, followed by gene functional assays to reveal the molecular mechanism ofH. axyridisleg regenerative growth process. Signaling pathways including Decapentaplegic (Dpp), Wingless (Wg), Ds/Ft/Hippo, Notch, Egfr, and Hedgehog (Hh) were all upregulated during the leg regenerative patterning and growth. Among these, Hh and its auxiliary receptor Lrp2 were required for the proper patterning and growth of the regenerative leg. The targets of canonical Hh signaling were required for the regenerative growth which contributes to the leg length, but were not essential for the pattern formation of the regenerative leg.dpp,wgand leg developmental-related genes includingrn,dacandDllwere all regulated byhhandlrp2and may play an essential role in the regenerative patterning of the leg.

Automated summary

Appendage regeneration in Harmonia axyridis, a model organism with advantages of short life cycle and strong regeneration capacity, involves upregulation of multiple signaling pathways such as Dpp, Wg, Ds/Ft/Hippo, Notch, Egfr, and Hh. The canonical Hh signaling and its auxiliary receptor Lrp2 are crucial for proper patterning and growth of the regenerative leg, while genes related to leg development are regulated by Hh and Lrp2, contributing to both leg length and pattern formation.