Autophagy precedes apoptosis during the remodeling of silkworm larval midgut

【作者】 Eleonora Franzetti； 黄志君； Yan-Xia Shi； Kun Xie； Xiao-Juan Deng； Jian-Ping Li； Qing-Rong Li； Wan-Ying Yang； Wen-Nian Zeng； Morena Casartelli； Hui-Min Deng； Silvia Cappellozza； Annalisa Grimaldi； Qingyou Xia； 冯启理； 曹阳； Gianluca Tettamanti；

【Author】 Eleonora Franzetti;Zhi-Jun Huang;Yan-Xia Shi;Kun Xie;Xiao-Juan Deng;Jian-Ping Li;Qing-Rong Li;Wan-Ying Yang;Wen-Nian Zeng;Morena Casartelli;Hui-Min Deng;Silvia Cappellozza;Annalisa Grimaldi;Qingyou Xia;Qili Feng;Yang Cao;Gianluca Tettamanti;Department of Biotechnology and Life Sciences,University of Insubria;Laboratory of Insect Molecular Biology and Biotechnology,Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding,College of Animal Science,South China Agricultural University;The Sericulture & Agri-Food Research Institute,Guangdong Academy of Agricultural Sciences;Department of Biology,Universita" degli Studi di Milano;Guangdong Provincial Key Lab of Biotechnology for Plant Development,School of Life Sciences,South China Normal University;CRA- Honey Bee and Silkworm Research Unit;Institute of Sericulture and Systems Biology,Southwest University;

【机构】 Department of Biotechnology and Life Sciences,University of Insubria； Laboratory of Insect Molecular Biology and Biotechnology,Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding,College of Animal Science,South China Agricultural University； The Sericulture & Agri-Food Research Institute,Guangdong Academy of Agricultural Sciences； Department of Biology,Universita" degli Studi di Milano； Guangdong Provincial Key Lab of Biotechnology for Plant Development,School of Life Sciences,South China Normal University； CRA- Honey Bee and Silkworm Research Unit； Institute of Sericulture and Systems Biology,Southwest University；

【摘要】 Although several features of apoptosis and autophagy have been reported in the larval organs of Lepidoptera during metamorphosis,solid experimental evidence for autophagy is still lacking.Moreover,the role of the two processes and the nature of their relationship are still cryptic.In this study,we perform a cellular,biochemical and molecular analysis of the degeneration process that occurs in the larval midgut of Bombyx mori during larval-adult transformation,with the aim to analyze autophagy and apoptosis in cells that die under physiological conditions.We demonstrate that larval midgut degradation is due to the concerted action of the two mechanisms,which occur at different times and have different functions.Autophagy is activated from the wandering stage and reaches a high level of activity during the spinning and prepupal stages,as demonstrated by specific autophagic markers.Our data show that the process of autophagy can recycle molecules from the degenerating cells and supply nutrients to the animal during the non-feeding period.Apoptosis intervenes later.In fact,although genes encoding caspases are transcribed at the end of the larval period,the activity of these proteases is not appreciable until the second day of spinning and apoptotic features are observable from prepupal phase.The abundance of apoptotic features during the pupal phase,when the majority of the cells die,indicates that apoptosis is actually responsible for cell death and for the disappearance of larval midgut cells.更多还原

【Abstract】 Although several features of apoptosis and autophagy have been reported in the larval organs of Lepidoptera during metamorphosis,solid experimental evidence for autophagy is still lacking.Moreover,the role of the two processes and the nature of their relationship are still cryptic.In this study,we perform a cellular,biochemical and molecular analysis of the degeneration process that occurs in the larval midgut of Bombyx mori during larval-adult transformation,with the aim to analyze autophagy and apoptosis in cells that die under physiological conditions.We demonstrate that larval midgut degradation is due to the concerted action of the two mechanisms,which occur at different times and have different functions.Autophagy is activated from the wandering stage and reaches a high level of activity during the spinning and prepupal stages,as demonstrated by specific autophagic markers.Our data show that the process of autophagy can recycle molecules from the degenerating cells and supply nutrients to the animal during the non-feeding period.Apoptosis intervenes later.In fact,although genes encoding caspases are transcribed at the end of the larval period,the activity of these proteases is not appreciable until the second day of spinning and apoptotic features are observable from prepupal phase.The abundance of apoptotic features during the pupal phase,when the majority of the cells die,indicates that apoptosis is actually responsible for cell death and for the disappearance of larval midgut cells.更多还原