ABSTRACT

The immunodeficiency observed in HIV-1-infected patients is mainly due to uninfected bystander CD4⁺ T lymphocyte cell death. The viral envelope glycoproteins (Env), expressed at the surface of infected cells, play a key role in this process. Env triggers macroautophagy/autophagy, a process necessary for subsequent apoptosis, and the production of reactive oxygen species (ROS) in bystander CD4⁺ T cells. Here, we demonstrate that Env-induced oxidative stress is responsible for their death by apoptosis. Moreover, we report that peroxisomes, organelles involved in the control of oxidative stress, are targeted by Env-mediated autophagy. Indeed, we observe a selective autophagy-dependent decrease in the expression of peroxisomal proteins, CAT and PEX14, upon Env exposure; the downregulation of either BECN1 or SQSTM1/p62 restores their expression levels. Fluorescence studies allowed us to conclude that Env-mediated autophagy degrades these entire organelles and specifically the mature ones. Together, our results on Env-induced pexophagy provide new clues on HIV-1-induced immunodeficiency.

Abbreviations: Ab: antibodies; AF: auranofin; AP: anti-proteases; ART: antiretroviral therapy; BafA₁: bafilomycin A₁; BECN1: beclin 1; CAT: catalase; CD4: CD4 molecule; CXCR4: C-X-C motif chemokine receptor 4; DHR123: dihydrorhodamine 123; Env: HIV-1 envelope glycoproteins; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; GFP-SKL: GFP-serine-lysine-leucine; HEK: human embryonic kidney; HIV-1: type 1 human immunodeficiency virus; HTRF: homogeneous time resolved fluorescence; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NAC: N-acetyl-cysteine; PARP: poly(ADP-ribose) polymerase; PEX: peroxin; ROS: reactive oxygen species; siRNA: small interfering ribonucleic acid; SQSTM1/p62: sequestosome 1.

摘要

在 HIV-1 感染患者中观察到的免疫缺陷主要是由于未感染的旁观者 CD4 ⁺ T 淋巴细胞死亡。在受感染细胞表面表达的病毒包膜糖蛋白 (Env) 在此过程中起关键作用。^{Env 触发巨自噬/自噬，这是随后细胞凋亡所必需的过程，以及旁观者 CD4 +}中活性氧 (ROS) 的产生T细胞。在这里，我们证明 Env 诱导的氧化应激是导致它们因细胞凋亡而死亡的原因。此外，我们报告过氧化物酶体，即参与控制氧化应激的细胞器，是 Env 介导的自噬的目标。事实上，我们观察到在 Env 暴露后，过氧化物酶体蛋白 CAT 和 PEX14 表达的选择性自噬依赖性降低。BECN1 或 SQSTM1/p62 的下调恢复了它们的表达水平。荧光研究让我们得出结论，Env 介导的自噬会降解这些整个细胞器，特别是成熟的细胞器。总之，我们关于 Env 诱导的 pexophagy 的结果为 HIV-1 诱导的免疫缺陷提供了新的线索。

缩写： Ab：抗体；AF：金诺芬；AP：抗蛋白酶；ART：抗逆转录病毒疗法；BafA ₁：巴弗洛霉素 A ₁；BECN1：beclin 1；CAT：过氧化氢酶；CD4：CD4分子；CXCR4：CXC基序趋化因子受体4；DHR123：二氢罗丹明 123；Env：HIV-1 包膜糖蛋白；GAPDH：3-磷酸甘油醛脱氢酶；GFP：绿色荧光蛋白；GFP-SKL：GFP-丝氨酸-赖氨酸-亮氨酸；HEK：人胚肾；HIV-1：1型人类免疫缺陷病毒；HTRF：均质时间分辨荧光；MAP1LC3/LC3：微管相关蛋白1轻链3；NAC：N-乙酰半胱氨酸；PARP：聚（ADP-核糖）聚合酶；PEX：过氧化物；ROS：活性氧；siRNA：小干扰核糖核酸；SQSTM1/p62：sequestosome 1。