Cloning, Expression Analysis, 20-Hydroxyecdysone Induction, and RNA Interference Study of Autophagy-Related Gene 8 from Heortia vitessoides Moore

Abstract

Autophagy is a highly conserved and regulated process in eukaryotic cells and remodels cytoplasm, recovers essential nutrients, and disposes of unwanted cytoplasmic components. Autophagy-related gene (ATG) 8, identified in Heortia vitessoides Moore, which is an oligophagous pest of Aquilaria sinensis (Lour.), was characterized (HvATG8). Multiple sequence alignment showed that HvATG8 possesses highly conserved domain structures. Stage-and tissue-specific expressions indicated that HvATG8 is highly expressed in prepupal, pupal, and adult stages and in the midgut of larvae and abdomen of adults. Lack of function of HvATG8 by RNA interference resulted in a significant decrease in survival rate and an increase in abnormal or nonviable phenotypes in H. vitessoides. Transition rate from larval to pupal stages was 33.0% and from pupal to adult stages was 15.0% after injection. Reduction of ATG8 expression reduced survival of H. vitessoides. Therefore, HvATG8 possibly plays a key role in normal growth stage of H. vitessoides. HvATG8 suppression downregulates HvATG3 expression, suggesting that the two genes are interconnected. Further, HvATG8 expression increased by 20-hydroxyecdysone treatment, starvation, and extreme temperature exposure. Starvation also altered expression of other ATGs in H. vitessoide. This study may be used to guide research on molecular mechanisms of autophagy in insects.Insects 2020, 11, 245 2 of 16 Autophagy is a self-digesting system of cells, which plays a pivotal role in maintaining the stability of the intracellular environment [9]. Three different types have been mentioned to date: microautophagy, chaperone-mediated autophagy, and macroautophagy [10]. Microautophagy means autonomous depression and deformation of lysosomal membranes or vacuolar membranes, which envelop and engulf part of the cytoplasm. An autophagy vesicle has a double-layer membrane structure, and its outer membrane can be fused with the lysosomal membrane. After autophagy vesicles enter the lysosome, the inner membrane is rapidly degraded, and vesicle contents are released, which is degraded by the hydrolytic enzyme; this allows cells to reuse substrates. In chaperone-mediated autophagy, receptors on the surface of lysosomal membranes selectively bind to soluble cytosolic proteins and regulate their transport to lysosomes. The formed chaperone-substrate complex is bound to the receptor of the lysosomal membrane, and the substrate is transported by the secondary chaperone protein in the cavity [11]. Macroautophagy, a degradation process focused on eliminating macromolecules and organelles, is the main pathway of autophagy in eukaryotic cells, which communicates a highly conducted self-degradation process that is started as an adaptive response under adverse conditions, for instance, nutritional removal. Usually, autophagy is referred to as macroautophagy. It is an intracellular process that degrades proteins in cytoplasmic components and organelles using lysosomes in eukaryote organisms ranging from yeast to mammals [11]. Auto...

Characterization of Chitin Synthase B Gene (HvChsb) and the Effects on Feeding Behavior in Heortia vitessoides Moore

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“…Autophagy is ubiquitous in eukaryotic cells, which is a highly conserved and homeostatic process. 46 Under normal circumstances, autophagy can maintain the stability of the intracellular environment by removing the damaged organelles, etc. 47 However, over activation of autophagy can induce the excessive degradation of cellular contents, thereby resulting in the impaired cell function and autophagic death.…”

Chromosomal-Level Reference Genome of the Moth Heortia Vitessoides (Lepidoptera: Crambidae), A Major Pest of Agarwood-Producing Trees

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