FURIN Mediated SARS-CoV-2 Spike Protein Cleavage and Endocytosis

Stable Identifier
Reaction [transition]
Homo sapiens
Related Species
Severe acute respiratory syndrome coronavirus 2
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In a SARS-CoV-2 infection the cellular protease furin cleaves the spike protein at the S1/S2 site and that cleavage is essential for S-protein-mediated cell-cell fusion and entry into human lung cells. The furin cleavage site promotes increased spike cleavage that has implications for pathogenesis (Hoffman et al. 2020; Johnson et al, 2021). Furin is associated with the plasma membrane of the host cell and mediates the hydrolytic cleavage of SARS-CoV-2 Spike (S) protein component of the viral membrane-associate S3:M:E:encapsidated SARS coronavirus genomic RNA: 7a:O-glycosyl 3a tetramer complex associated with ACE2. Spike cleavage by furin is affected by O-glycosylations around the cleavage site at position 685-686. In particular the P681 mutation, which occurs in the SARS-CoV-2 alpha and delta variants, results in decreased O-glycosylation, increased furin cleavage, and increased syncytia formation which may contribute to increased viral infectivity (Zhang et al, 2021a).

Neuropilin-1 (NRP1) is a receptor expressed in a broad range of cells from human organ systems including respiratory, urinary, digestive, reproductive, and immune systems. Specific cell lines from these organs are susceptible to SARS-CoV-2 infection. From these A549 (lung) and HRC45 (kidney) cells had a robust SARS‐CoV‐2 pseudovirus infection but weak levels of ACE2, and both expressed strong levels of NRP1 (Zhang et al, 2021b). High levels of NRP1 were detected in the epithelial surface layer of the human respiratory and olfactory epithelium, with ACE2 hardly detectable in these tissues. Artificial additional NRP1 expression in Caco-2 and HEK-293T cells increased SARS-CoV-2 infection markedly (Cantuti-Castelvetri et al, 2020; Zhu et al, 2021). The furin-cleaved SARS-CoV-2 spike glycoprotein fragment S1 binds NRP1, and selective NRP1 inhibitors reduced SARS-CoV-2 entry and infectivity in Caco-2 cell culture (Daly et al, 2020). Taken together, NRP1 appears to be the entry factor on NRP1-rich cells, and a weak entry factor on cells where ACE2 is present.

Several cell lines also have relatively higher levels of Hepatitis A virus cellular receptor 1 (kidney injury molecule-1, HAVCR1, KIM1, TIM1), a membrane protein upregulated upon kidney injury. Recombinant HAVCR1 blocked infection of both SARS‐CoV‐2 and SARS‐CoV pseudoviruses in a dose‐dependent fashion in one‐way ANOVA analysis albeit no significant difference was detected when the treated groups were compared with the untreated infected group (Zhang et al, 2021b). HAVCR1 binds to SARS-CoV-2 spike glycoprotein. Uptake of spike virosomes by lung and kidney epithelial cells that naturally express HAVCR1 was inhibited by anti-HAVCR1 antibodies and a HAVCR1 inhibitor (Mori et al, 2022; Yang et al, 2021).

Heparin effectively inhibits SARS-CoV-2 spike (S) cleavage into S1, S2 by furin. Unfractionated heparin (UFH) exhibits a higher furin inhibitory potency than the low-molecular-weight heparin (LMWH) (Paiardi et al, 2021).

Literature References
PubMed ID Title Journal Year
34324210 SARS-CoV-2 pseudovirus infectivity and expression of viral entry-related factors ACE2, TMPRSS2, Kim-1, and NRP-1 in human cells from the respiratory, urinary, digestive, reproductive, and immune systems

Zhang, H, Ramos da Silva, S, Guo, H, Li, W, Chang, Y, Feng, J, Gao, SJ, Ju, E, Zhang, F, Moore, PS

J Med Virol 2021
33494095 Loss of furin cleavage site attenuates SARS-CoV-2 pathogenesis

Suthar, MS, Zhang, L, An, Z, Diamond, MS, Lee, B, Shi, PY, Weaver, SC, Debbink, K, Zhang, X, Vanderheiden, A, Winkler, ES, Popov, V, Ren, P, Menachery, VD, Muruato, A, Vu, M, Routh, AL, Freiberg, AN, Aguilar, P, Xie, X, Bailey, AL, Juelich, T, Ku, Z, Bopp, N, Plante, JA, Swetnam, D, Smith, JK, Schindewolf, C, Plante, KS, Lokugamage, KG, Kalveram, B, Johnson, BA, Zou, J

Nature 2021
33082294 Neuropilin-1 is a host factor for SARS-CoV-2 infection

Simón-Gracia, L, Williamson, MK, Chen, KE, Yamauchi, Y, Hollandi, R, Klein, K, Helenius, A, Matthews, DA, Cullen, PJ, Antón-Plágaro, C, Simonetti, B, Daly, JL, Hiscox, JA, Bauer, M, Teesalu, T, Sessions, RB, Horvath, P, Shoemark, DK, Davidson, AD, Collins, BM, Greber, UF

Science 2020
32532959 The role of furin cleavage site in SARS-CoV-2 spike protein-mediated membrane fusion in the presence or absence of trypsin

Jiang, S, Lu, L, Liu, Z, Wang, Q, Su, S, Zhu, Y, Xia, S, Xu, W, Wang, X, Lan, Q

Signal Transduct Target Ther 2020
21068237 A transmembrane serine protease is linked to the severe acute respiratory syndrome coronavirus receptor and activates virus entry

Perlman, S, Shulla, A, Zhao, J, Gallagher, T, Heald-Sargent, T, Subramanya, G

J. Virol. 2011
34431042 Genome-wide CRISPR activation screen identifies candidate receptors for SARS-CoV-2 entry

Tian, F, Liu, Y, Niu, X, Chen, A, Wang, C, Du, S, Zhang, Z, Zhou, Z, Dong, X, Xiao, J, Wang, J, Xiao, X, Zhu, S, Chen, S, Wei, W, Li, Q, Liu, Z, Xu, Y, Pan, Q

Sci China Life Sci 2021
33082293 Neuropilin-1 facilitates SARS-CoV-2 cell entry and infectivity

Helenius, A, Vapalahti, O, Cantuti-Castelvetri, L, Levanov, L, Djannatian, M, Szirovicza, L, Winkler, MS, Teesalu, T, Ojha, R, Hepojoki, J, Meunier, FA, Pedro, LD, Österlund, P, Mollenhauer, B, Anastasina, M, Kallio-Kokko, H, Kuivanen, S, van der Meer, F, Kallio, K, Franz, J, Butcher, SJ, Stadelmann, C, Balistreri, G, Gokce, O, Tobi, A, Smura, T, Kaya, T, Simons, M, Joensuu, M

Science 2020
32995803 KIM-1/TIM-1 is a Receptor for SARS-CoV-2 in Lung and Kidney

Mori, Y, Padera, RF, Fink, C, Dekaban, GA, Bonventre, JV, Sako, K, Dikeakos, JD, Weins, A, Song, M, Aschauer, P, Hong, S, Ichimura, T, Nasr, ML, Lee, NN, Lee, LP, Mori, M, Padmanabha Das, KM

medRxiv 2022
33493263 Kidney injury molecule-1 is a potential receptor for SARS-CoV-2

Xiong, M, Zhang, Y, Wang, X, Yang, C, Chen, H, Shen, Z, Chen, H, Liu, X, Huang, K, Yang, D, Zeng, X, Chen, Y

J Mol Cell Biol 2021
32703818 TMPRSS2 and furin are both essential for proteolytic activation of SARS-CoV-2 in human airway cells

Eickmann, M, Heindl, MR, Garten, W, Rohde, C, Bestle, D, Van Lam van, T, Stein, DA, Moulton, H, Dolnik, O, Pilgram, O, Klenk, HD, Limburg, H, Böttcher-Friebertshäuser, E, Hardes, K, Steinmetzer, T

Life Sci Alliance 2020
34732583 Furin cleavage of the SARS-CoV-2 spike is modulated by O-glycosylation

Samara, NL, Syed, ZA, Mann, M, Tabak, LA, Ten Hagen, KG, Tian, E, Reynolds, HM, Zeldin, DC, Zhang, L

Proc Natl Acad Sci U S A 2021
32362314 A Multibasic Cleavage Site in the Spike Protein of SARS-CoV-2 Is Essential for Infection of Human Lung Cells

Pöhlmann, S, Hoffmann, M, Kleine-Weber, H

Mol. Cell 2020
Catalyst Activity

serine-type endopeptidase activity of FURIN [plasma membrane]

This event is regulated