title: Autophagy precedes apoptosis during the remodeling of silkworm larval midgut.
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.
authors: Department of Biotechnology and Life Sciences, University of Insubria, Via J. H. Dunant, 3 21100, Varese, Italy.
authors: Eleonora
authors: E
authors: Franzetti
authors: Zhi-Jun
authors: ZJ
authors: Huang
authors: Yan-Xia
authors: YX
authors: Shi
authors: Kun
authors: K
authors: Xie
authors: Xiao-Juan
authors: XJ
authors: Deng
authors: Jian-Ping
authors: JP
authors: Li
authors: Qing-Rong
authors: QR
authors: Li
authors: Wan-Ying
authors: WY
authors: Yang
authors: Wen-Nian
authors: WN
authors: Zeng
authors: Morena
authors: M
authors: Casartelli
authors: Hui-Min
authors: HM
authors: Deng
authors: Silvia
authors: S
authors: Cappellozza
authors: Annalisa
authors: A
authors: Grimaldi
authors: Qingyou
authors: Q
authors: Xia
authors: Qili
authors: Q
authors: Feng
authors: Yang
authors: Y
authors: Cao
authors: Gianluca
authors: G
authors: Tettamanti
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001343:Autophagy / Q000235:genetics / Q000502:physiology*; D012831:Bombyx / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D004064:Digestive System / Q000033:anatomy & histology / Q000378:metabolism; D007814:Larva / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D008675:Metamorphosis, Biological / Q000502:physiology*; D011679:Pupa / Q000378:metabolism
chemical_list: D020169:Caspases