Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
Cells. 2023 Mar 15;12(6):899. doi: 10.3390/cells12060899.
Homologs of Autophagy-related (Atg) protein 4 are reported to cleave LC3 protein and facilitate autophagy occurrence differently in mammals, whereas their functions have not been investigated in insects. Three homologs, including and its short form as well as exist in . Herein, the autophagic functions of BmAtg4a and BmAtg4b were investigated. qPCR detection found that and both peaked during larval-pupal metamorphosis when autophagy occurs robustly. Immunofluorescent staining showed that BmAtg4a was predominantly localized at the cytoplasm, while BmAtg4b had notable nuclear localization. Overexpression of and both slightly promoted basal autophagy but inhibited the autophagy induced by the infection of nucleopolyhedrovirus (BmNPV) and, thereby, its proliferation. In comparison, knockout of or significantly upregulated BmNPV-induced autophagy and its replication in BmN cells. Results of Co-immunoprecipitation associated with mass spectrum showed that the cytoskeleton protein actin A2 (BmACT2) and actin A1 (BmACT1) bound with BmAtg4a and BmAtg4b especially. Knockout of and inhibited BmAtg4b- and BmAtg4a-induced autophagy, respectively; moreover, knockout of reduced the ratio of cells with nuclear BmAtg4b. Of note, BmAtg4a and BmAtg4b had physical interaction, and they had an inhibitory effect on mutual autophagic function. In this work, we provide new insights into the autophagy machinery in insects as well as its function in the proliferation of BmNPV.
自噬相关 (Atg) 蛋白的同源物据报道在哺乳动物中以不同的方式切割 LC3 蛋白并促进自噬发生，而它们在昆虫中的功能尚未被研究。在 中存在三种同源物，包括 和其短形式 以及 。在此，研究了 BmAtg4a 和 BmAtg4b 的自噬功能。qPCR 检测发现 和 都在自噬发生旺盛的幼虫-蛹变态期达到峰值。免疫荧光染色显示 BmAtg4a 主要定位于细胞质，而 BmAtg4b 具有明显的核定位。过表达 和 均轻微促进基础自噬，但抑制感染 核多角体病毒 (BmNPV) 和 引起的自噬，从而抑制其增殖。相比之下， 或 的敲除显著上调了 BmNPV 诱导的自噬及其在 BmN 细胞中的复制。与质谱相关的共免疫沉淀结果表明，细胞骨架蛋白 肌动蛋白 A2 (BmACT2) 和 肌动蛋白 A1 (BmACT1) 与 BmAtg4a 和 BmAtg4b 结合特别紧密。 或 的敲除抑制了 BmAtg4b 和 BmAtg4a 诱导的自噬；此外， 的敲除降低了具有核 BmAtg4b 的细胞比例。值得注意的是，BmAtg4a 和 BmAtg4b 具有物理相互作用，并且它们对彼此的自噬功能具有抑制作用。在这项工作中，我们为昆虫的自噬机制及其在 BmNPV 增殖中的功能提供了新的见解。
