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Functional identification of Bombyx mori Atg13 in autophagy.

Archives of insect biochemistry and physiology (2020-06-10)
Shuyan Li, Jing Xu, Xianying Xu, Weiyuan Ma, Ling Tian, Kang Li
ABSTRACT

The autophagy process involves a series of autophagy-related (Atg) proteins, which are conserved in eukaryotes. ULK1/Atg1-ATG13/Atg13 is the core protein complex for autophagy initiation in response to nutrient and hormone signaling. However, how Atg13 is regulated to participate in autophagy is unclear in insects. Here in Bombyx mori, the variation of BmAtg13 was correlated with autophagy induced by steroid hormone 20-hydroxyecdysone (20E) or starvation. Developmental profiles from feeding to prepupal stage revealed that there were two bands of BmAtg13 protein detected by western blot analysis, therein the upper band was intensively decreased, while the lower band was significantly increased which was in accordance with its mRNA variation; and immunofluorescent staining indicated that BmAtg13 was nucleocytoplasmic translocated during larval-pupal metamorphosis when autophagy was dramatically induced. BmAtg13 knockdown and overexpression both inhibits autophagy. Besides, 20E treatment-induced BmAtg13 gene expression, while blocking 20E signaling transduction by knockdown of BmUsp reduced both gene expression and protein level of BmAtg13. These results reveal that BmAtg13 is required for 20E- and starvation-induced autophagy in B. mori, which provides the foundation for further related studies.

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