Journal of Biological Chemistry
Volume 296, January–June 2021, 100306
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Research Article
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SARS-CoV-2 infects cells after viral entry via clathrin-mediated endocytosis

https://doi.org/10.1016/j.jbc.2021.100306Get rights and content
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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of COVID-19, so understanding its biology and infection mechanisms is critical to facing this major medical challenge. SARS-CoV-2 is known to use its spike glycoprotein to interact with the cell surface as a first step in the infection process. As for other coronaviruses, it is likely that SARS-CoV-2 next undergoes endocytosis, but whether or not this is required for infectivity and the precise endocytic mechanism used are unknown. Using purified spike glycoprotein and lentivirus pseudotyped with spike glycoprotein, a common model of SARS-CoV-2 infectivity, we now demonstrate that after engagement with the plasma membrane, SARS-CoV-2 undergoes rapid, clathrin-mediated endocytosis. This suggests that transfer of viral RNA to the cell cytosol occurs from the lumen of the endosomal system. Importantly, we further demonstrate that knockdown of clathrin heavy chain, which blocks clathrin-mediated endocytosis, reduces viral infectivity. These discoveries reveal that SARS-CoV-2 uses clathrin-mediated endocytosis to gain access into cells and suggests that this process is a key aspect of virus infectivity.

Keywords

clathrin
COVID-19
dynamin
endocytosis
infection
SARS-CoV-2
virus entry

Abbreviations

ACE2
angiotensin-converting enzyme 2
CHC
clathrin heavy chain
CQ
chloroquine
MERS-CoV
Middle-East respiratory syndrome coronavirus
SARS-CoV
severe acute respiratory syndrome coronavirus
SARS-CoV-2
severe acute respiratory syndrome coronavirus 2
Tf
transferrin
TfR
Tf receptor

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Armin Bayati is a PhD student at McGill University, in Integrated Program in Neuroscience under the supervision of Dr Peter McPherson. Armin is interested in the endocytic pathways taken by pathogens such as prions, aggregated proteins, and viruses, which is why he was interested to investigate SARS-CoV-2. Following the COVID-19 project, Armin’s research will be focusing on Parkinson’s disease, specifically on the endocytosis and trafficking of alpha-synuclein protofibrils. Once established, Armin will then explore the mechanisms underlying formation of cytoplasmic aggregates by alpha-synuclein fibrils. Armin's research could lead to significant advancement in our understanding of Parkinson's disease pathophysiology and the developing of treatments for the disease.

Rahul Kumar is a graduate student in the lab of Dr Peter McPherson at McGill University. His research is focused on understanding regulation of small GTPases in membrane trafficking. Early in the COVID-19 pandemic, Dr McPherson’s lab turned their attention to study entry mechanism of SARS-Cov-2 using their long-standing expertise in cell biology of neurological diseases, which led to the discovery of clathrin-mediated endocytosis of SARS-Cov-2 as a first step in viral infection. With the completion of this project, Kumar is now focused on his thesis work—understanding the regulation of Rab GTPases by DENN domain containing proteins, guanine nucleotide exchange factors (GEFs) for Rabs. As many DENN domain proteins have mutations linked to human diseases, it is exciting time to characterize many of the uncharacterized members of DENN domain family and study their underlying molecular mechanisms.

This article contains supporting information.

These authors contributed equally to this work.