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  • Steroid hormone 20-hydroxyecdysone induces the transcription and complex assembly of V-ATPases to facilitate autophagy in Bombyx mori.

Steroid hormone 20-hydroxyecdysone induces the transcription and complex assembly of V-ATPases to facilitate autophagy in Bombyx mori.

Insect biochemistry and molecular biology (2019-10-28)
Yichen Dai, Kang Li, Wenmei Wu, Kunzhong Wu, Huiyu Yi, Wangyu Li, Yang Xiao, Yangjin Zhong, Yang Cao, Ling Tian
ABSTRACT

Vacuolar-type H + -adenosine triphosphatases (V-ATPases) are indispensable for lysosome acidification and participate in autophagic processes. The steroid hormone 20-hydroxyecdysone (20E) predominantly induces autophagy and regulates insect larval molting and metamorphosis; however, the specific mechanism of lysosome acidification regulation by 20E remains unclear. Here, we showed that the developmental profiles of Bombyx V-ATPases were in accordance with autophagy occurrence and lysosome acidification in the fat body during larval-pupal metamorphosis. BmV-ATPase-A and BmV-ATPase-B were required for lysosome acidification and autophagic flux. Both 20E treatment and starvation were able to induce lysosome acidification. Furthermore, BmV-ATPase transcription was induced by 20E treatment and reduced by RNAi targeting the 20E receptor BmUsp. On the one hand, 20E upregulated the transcription of BmV-ATPases through inducing Bombyx transcription factor EB (TFEB) and its nuclear translocation; on the other hand, 20E inhibited mTOR signaling to induce the transcription and assembly of BmV-ATPase subunits. Overall, 20E induces lysosome acidification by upregulating the transcription and assembly of V-ATPase subunits via activating BmTFEB and cooperating with nutrient signaling. These findings improve our understanding of the regulatory mechanisms underlying lysosome acidification and autophagic flux in Bombyx mori.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
20-Hydroxyecdysone, ≥93% (HPLC), powder
Sigma-Aldrich
Grace′s Insect Medium, With L-glutamine, without sodium bicarbonate, powder, suitable for insect cell culture