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Abstract: FR-PO007

SARS-CoV-2 S Protein Is a Competitive Inhibitor of Furin Mediated ENaC Activation

Session Information

Category: Coronavirus (COVID-19)

  • 000 Coronavirus (COVID-19)

Authors

  • Magaña, German R., Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, Ciudad de Mexico, Mexico
  • Garcia Avila, Kevin, Instituto Tecnologico y de Estudios Superiores de Monterrey, Ciudad de Mexico, Ciudad de Mexico, Mexico
  • Carbajal-Contreras, Hector, Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, Ciudad de Mexico, Mexico
  • Plata, Consuelo, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico
  • Moreno, Erika, Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, Ciudad de Mexico, Mexico
  • Vázquez, Norma Hilda, Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, Ciudad de Mexico, Mexico
  • Gamba, Gerardo, Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, Ciudad de Mexico, Mexico
  • Castañeda-Bueno, Maria, Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, Ciudad de Mexico, Mexico

Group or Team Name

  • Unidad de Fisiología Molecular
Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of COVID-19 (Coronavirus disease 19). SARS-CoV-2 causes a multisystemic infection, which frequently presents with pulmonary oedema, endothelial damage and electrolytic abnormalities. An essential physiopathological feature of SARS-CoV-2 involves cleavage of its S protein by furin or furin-like enzymes. It has been shown by sequence-based evidence that the S protein polybasic aminoacid sequence is identical to the consensus sequence for furin cleavage present in the human alpha subunit of the epithelial sodium channel (ENaC). Furin and furin-like enzymes are also involved in the posttranslational regulation of ENaC in many tissues, including the lung, endothelium, and the kidney, where cleavage is associated with increased activity of the channel. ENaC is involved in the regulation of fluid clearance, Na+, K+ and acid-base homeostasis, and endothelial function. Thus, we hypothesized that the S protein competes with ENaC for furin-mediated cleavage and activation.

Methods

We injected synthetic mRNA encoding WT S protein and mutant S protein lacking the furin consensus sequence (Δ-Spike) into X. laevis oocytes with αβγ-ENaC subunits. We then performed whole-cell voltage-clamp experiments and protein analysis by western blot.

Results

We observed an interdependent competitive effect on the cleavage of both the S protein and ENaC when co-expressed, which was partially prevented with the injection of Δ-Spike. We also found a decrease in the amiloride-sensitive sodium current in oocytes injected with the WT S protein but not with Δ-Spike. This suggests diminished function of ENaC in the presence of WT S protein that depends on its furin cleavage site.

Conclusion

These findings show evidence of a competitive interaction between the S protein and ENaC for furin-like enzymes. This suggests that SARS-CoV-2 infection may impair ENaC activity in human epithelia, which gives a plausible explanation to pulmonary oedema, endothelial damage, and electrolyte disturbances in patients with COVID-19.

Funding

  • Government Support – Non-U.S.