SARS-CoV-2 蛋白对自噬的调控。
Manipulation of autophagy by SARS-CoV-2 proteins.
机构信息
Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany.
出版信息
Autophagy. 2021 Sep;17(9):2659-2661. doi: 10.1080/15548627.2021.1953847. Epub 2021 Jul 19.
As part of innate immune defenses, macroautophagy/autophagy targets viruses and viral components for lysosomal degradation and exposes pathogen-associated molecular patterns to facilitate recognition. However, viruses evolved sophisticated strategies to antagonize autophagy and even exploit it to promote their replication. In our recent study, we systematically analyzed the impact of individual SARS-CoV-2 proteins on autophagy. We showed that E, M, ORF3a, and ORF7a cause an accumulation of autophagosomes, whereas Nsp15 prevents the efficient formation of autophagosomes. Consequently, autophagic degradation of SQSTM1/p62 is decreased in the presence of E, ORF3a, ORF7a, and Nsp15. Notably, M does not alter SQSTM1 protein levels and colocalizes with accumulations of LC3B-positive membranes not resembling vesicles. Infection with SARS-CoV-2 prevents SQSTM1 degradation and increases lipidation of LC3B, indicating overall that the infection causes a reduction of autophagic flux. Our mechanistic analyses showed that the accessory proteins ORF3a and ORF7a both block autophagic degradation but use different strategies. While ORF3a prevents the fusion between autophagosomes and lysosomes, ORF7a reduces the acidity of lysosomes. In summary, we found that Nsp15, E, M, ORF3a, and ORF7a of SARS-CoV-2 manipulate cellular autophagy, and we determined the molecular mechanisms of ORF3a and ORF7a.
作为先天免疫防御的一部分,巨自噬/自噬将病毒和病毒成分靶向溶酶体降解,并暴露病原体相关分子模式,以促进识别。然而,病毒进化出了复杂的策略来拮抗自噬,甚至利用它来促进自身复制。在我们最近的研究中,我们系统地分析了 SARS-CoV-2 单个蛋白对自噬的影响。我们发现 E、M、ORF3a 和 ORF7a 导致自噬体的积累,而 Nsp15 阻止自噬体的有效形成。因此,在存在 E、ORF3a、ORF7a 和 Nsp15 的情况下,SQSTM1/p62 的自噬降解减少。值得注意的是,M 不会改变 SQSTM1 蛋白水平,并与 LC3B 阳性膜的积累共定位,这些膜不像囊泡。SARS-CoV-2 的感染阻止了 SQSTM1 的降解,并增加了 LC3B 的脂质化,这表明感染总体上导致自噬通量的减少。我们的机制分析表明,辅助蛋白 ORF3a 和 ORF7a 都阻断自噬降解,但使用不同的策略。虽然 ORF3a 阻止自噬体与溶酶体融合,但 ORF7a 降低了溶酶体的酸度。总之,我们发现 SARS-CoV-2 的 Nsp15、E、M、ORF3a 和 ORF7a 操纵细胞自噬,并确定了 ORF3a 和 ORF7a 的分子机制。