tetano
Editor, Senior Moderator
mBio
. 2024 Feb 13:e0228723.
doi: 10.1128/mbio.02287-23. Online ahead of print. Calpain-2 mediates SARS-CoV-2 entry via regulating ACE2 levels
Qiru Zeng[SUP] 1 [/SUP], Avan Antia[SUP] 1 [/SUP], Luis Alberto Casorla-Perez[SUP] 2 [/SUP], Maritza Puray-Chavez[SUP] 1 [/SUP], Sebla B Kutluay[SUP] 1 [/SUP], Matthew A Ciorba[SUP] 2 [/SUP], Siyuan Ding[SUP] 1 [/SUP]
Affiliations
Since the beginning of the coronavirus disease 2019 (COVID-19) pandemic, much effort has been dedicated to identifying effective antivirals against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A number of calpain inhibitors show excellent antiviral activities against SARS-CoV-2 by targeting the viral main protease (M[SUP]pro[/SUP]), which plays an essential role in processing viral polyproteins. In this study, we found that calpain inhibitors potently inhibited the infection of a chimeric vesicular stomatitis virus (VSV) encoding the SARS-CoV-2 spike protein but not M[SUP]pro[/SUP]. In contrast, calpain inhibitors did not exhibit antiviral activities toward the wild-type VSV with its native glycoprotein. Genetic knockout of calpain-2 by CRISPR/Cas9 conferred resistance of the host cells to the chimeric VSV-SARS-CoV-2 virus and a clinical isolate of wild-type SARS-CoV-2. Mechanistically, calpain-2 facilitates SARS-CoV-2 spike protein-mediated cell attachment by positively regulating the cell surface levels of ACE2. These results highlight an M[SUP]pro[/SUP]-independent pathway targeted by calpain inhibitors for efficient viral inhibition. We also identify calpain-2 as a novel host factor and a potential therapeutic target responsible for SARS-CoV-2 infection at the entry step.IMPORTANCEMany efforts in small-molecule screens have been made to counter SARS-CoV-2 infection by targeting the viral main protease, the major element that processes viral proteins after translation. Here, we discovered that calpain inhibitors further block SARS-CoV-2 infection in a main protease-independent manner. We identified the host cysteine protease calpain-2 as an important positive regulator of the cell surface levels of SARS-CoV-2 cellular receptor ACE2 and, thus, a facilitator of viral infection. By either pharmacological inhibition or genetic knockout of calpain-2, the SARS-CoV-2 binding to host cells is blocked and viral infection is decreased. Our findings highlight a novel mechanism of ACE2 regulation, which presents a potential new therapeutic target. Since calpain inhibitors also potently interfere with the viral main protease, our data also provide a mechanistic understanding of the potential use of calpain inhibitors as dual inhibitors (entry and replication) in the clinical setting of COVID-19 diseases. Our findings bring mechanistic insights into the cellular process of SARS-CoV-2 entry and offer a novel explanation to the mechanism of activities of calpain inhibitors.
Keywords: SARS-CoV-2; antivirals; viral entry.
. 2024 Feb 13:e0228723.
doi: 10.1128/mbio.02287-23. Online ahead of print. Calpain-2 mediates SARS-CoV-2 entry via regulating ACE2 levels
Qiru Zeng[SUP] 1 [/SUP], Avan Antia[SUP] 1 [/SUP], Luis Alberto Casorla-Perez[SUP] 2 [/SUP], Maritza Puray-Chavez[SUP] 1 [/SUP], Sebla B Kutluay[SUP] 1 [/SUP], Matthew A Ciorba[SUP] 2 [/SUP], Siyuan Ding[SUP] 1 [/SUP]
Affiliations
- PMID: 38349185
- DOI: 10.1128/mbio.02287-23
Since the beginning of the coronavirus disease 2019 (COVID-19) pandemic, much effort has been dedicated to identifying effective antivirals against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A number of calpain inhibitors show excellent antiviral activities against SARS-CoV-2 by targeting the viral main protease (M[SUP]pro[/SUP]), which plays an essential role in processing viral polyproteins. In this study, we found that calpain inhibitors potently inhibited the infection of a chimeric vesicular stomatitis virus (VSV) encoding the SARS-CoV-2 spike protein but not M[SUP]pro[/SUP]. In contrast, calpain inhibitors did not exhibit antiviral activities toward the wild-type VSV with its native glycoprotein. Genetic knockout of calpain-2 by CRISPR/Cas9 conferred resistance of the host cells to the chimeric VSV-SARS-CoV-2 virus and a clinical isolate of wild-type SARS-CoV-2. Mechanistically, calpain-2 facilitates SARS-CoV-2 spike protein-mediated cell attachment by positively regulating the cell surface levels of ACE2. These results highlight an M[SUP]pro[/SUP]-independent pathway targeted by calpain inhibitors for efficient viral inhibition. We also identify calpain-2 as a novel host factor and a potential therapeutic target responsible for SARS-CoV-2 infection at the entry step.IMPORTANCEMany efforts in small-molecule screens have been made to counter SARS-CoV-2 infection by targeting the viral main protease, the major element that processes viral proteins after translation. Here, we discovered that calpain inhibitors further block SARS-CoV-2 infection in a main protease-independent manner. We identified the host cysteine protease calpain-2 as an important positive regulator of the cell surface levels of SARS-CoV-2 cellular receptor ACE2 and, thus, a facilitator of viral infection. By either pharmacological inhibition or genetic knockout of calpain-2, the SARS-CoV-2 binding to host cells is blocked and viral infection is decreased. Our findings highlight a novel mechanism of ACE2 regulation, which presents a potential new therapeutic target. Since calpain inhibitors also potently interfere with the viral main protease, our data also provide a mechanistic understanding of the potential use of calpain inhibitors as dual inhibitors (entry and replication) in the clinical setting of COVID-19 diseases. Our findings bring mechanistic insights into the cellular process of SARS-CoV-2 entry and offer a novel explanation to the mechanism of activities of calpain inhibitors.
Keywords: SARS-CoV-2; antivirals; viral entry.