Laguía Fernando, Chojnacki Jakub, Erkizia Itziar, Geli María Isabel, Enrich Carlos, Martinez-Picado Javier, Resa-Infante Patricia
IrsiCaixa, Badalona, Spain.
CIBERINFEC, Madrid, Spain.
Front Immunol. 2025 Jan 10;15:1505840. doi: 10.3389/fimmu.2024.1505840. eCollection 2024.
HIV-1 exploits dendritic cells (DCs) to spread throughout the body via specific recognition of gangliosides present on the viral envelope by the CD169/Siglec-1 membrane receptor. This interaction triggers the internalization of HIV-1 within a structure known as the sac-like compartment. While the mechanism underlying sac-like compartment formation remains elusive, prior research indicates that the process is clathrin-independent and cell membrane cholesterol-dependent and involves transient disruption of cortical actin. Here, we investigate the potential involvement of massive endocytosis (MEND) in this process.
We used live cell confocal imaging to measure the dimensions and dynamics of the compartment. We assessed the role of actin and cholesterol in fixed and live cells using confocal microscopy and evaluated the effect of PI3K and protein palmytoilation inhibitors during viral uptake.
Our data demonstrate extensive plasma membrane invagination based on sac-like compartment dimensions (2.9 μm in diameter and 20 μm in volume). We showed that the cholesterol concentration doubles within the regions of viral uptake, suggesting lipid-phase separation, and that development of the sac-like compartment is accompanied by transient depolarization of cortical actin. Moreover, we observed that protein palmitoylation and PI3K inhibition reduce the sac-like compartment formation rate from 70% to 20% and 40%, respectively.
Our results indicate the involvement of MEND mechanisms during sac-like compartment formation.
HIV-1通过CD169/Siglec-1膜受体特异性识别病毒包膜上的神经节苷脂，利用树突状细胞（DCs）在全身传播。这种相互作用触发HIV-1在一种称为囊样区室的结构内内化。虽然囊样区室形成的潜在机制仍然难以捉摸，但先前的研究表明，该过程不依赖网格蛋白且依赖细胞膜胆固醇，并涉及皮质肌动蛋白的短暂破坏。在此，我们研究巨胞饮作用（MEND）在这一过程中的潜在参与情况。
我们使用活细胞共聚焦成像来测量区室的尺寸和动力学。我们使用共聚焦显微镜评估肌动蛋白和胆固醇在固定细胞和活细胞中的作用，并在病毒摄取过程中评估PI3K和蛋白质棕榈酰化抑制剂的效果。
我们的数据表明，基于囊样区室的尺寸（直径2.9μm，体积20μm）存在广泛的质膜内陷。我们发现，在病毒摄取区域内胆固醇浓度翻倍，提示脂相分离，并且囊样区室的形成伴随着皮质肌动蛋白的短暂去极化。此外，我们观察到蛋白质棕榈酰化和PI3K抑制分别将囊样区室的形成率从70%降低到20%和40%。
我们的结果表明在囊样区室形成过程中存在MEND机制。
