SARS-CoV-2 mainly infects the respiratory tract but can also target other organs, including the central nervous system. While it was recently shown that cells of the blood-brain-barrier are permissive to SARS-CoV-2 infection , it remains debated whether neurons can be infected. In this study, we demonstrate that vesicular stomatitis virus particles pseudotyped with the spike protein of SARS-CoV-2 variants WT, Alpha, Delta and Omicron enter the neuronal model cell line SH-SY5Y. Cell biological analyses of the pseudo-virus treated cultures showed marked alterations in microtubules of SH-SY5Y cells. Because the changes in β-tubulin occurred in most cells, but only few were infected, we further asked whether interaction of the cells with spike protein might be sufficient to cause molecular and structural changes. For this, SH-SY5Y cells were incubated with trimeric spike proteins for time intervals of up to 24 h. CellProfiler™-based image analyses revealed changes in the intensities of microtubule staining in spike protein-incubated cells. Furthermore, expression of the spike protein-processing protease cathepsin L was found to be up-regulated by wild type, Alpha and Delta spike protein pseudotypes and cathepsin L was found to be secreted from spike protein-treated cells. We conclude that the mere interaction of the SARS-CoV-2 with neuronal cells can affect cellular architecture and proteolytic capacities. The molecular mechanisms underlying SARS-CoV-2 spike protein induced cytoskeletal changes in neuronal cells remain elusive and require future studies.

中文翻译：

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SARS-CoV-2 刺突蛋白与神经元模型细胞系 SH-SY5Y 相互作用导致细胞骨架 β-微管蛋白和半胱氨酸组织蛋白酶 L 失调

SARS-CoV-2 主要感染呼吸道，但也可以针对其他器官，包括中枢神经系统。虽然最近表明血脑屏障细胞允许 SARS-CoV-2 感染，但神经元是否可以被感染仍存在争议。在这项研究中，我们证明用 SARS-CoV-2 变体 WT、Alpha、Delta 和 Omicron 的刺突蛋白假型化的水疱性口炎病毒颗粒进入神经元模型细胞系 SH-SY5Y。假病毒处理培养物的细胞生物学分析显示 SH-SY5Y 细胞的微管发生显着变化。由于β-微管蛋白的变化发生在大多数细胞中，但只有少数细胞被感染，我们进一步询问细胞与刺突蛋白的相互作用是否足以引起分子和结构的变化。为此，SH-SY5Y 细胞与三聚刺突蛋白一起孵育长达 24 小时的时间间隔。基于 CellProfiler™ 的图像分析揭示了刺突蛋白孵育细胞中微管染色强度的变化。此外，发现野生型、Alpha 和 Delta 刺突蛋白假型上调刺突蛋白加工蛋白酶组织蛋白酶 L 的表达，并且发现刺突蛋白处理的细胞分泌组织蛋白酶 L。我们得出的结论是，SARS-CoV-2 与神经元细胞的相互作用就会影响细胞结构和蛋白水解能力。 SARS-CoV-2 刺突蛋白诱导神经元细胞骨架变化的分子机制仍然难以捉摸，需要进一步研究。