Structural modeling of protein ensembles between E3 RING ligases and SARS-CoV-2: The role of zinc binding domains

Proteomics suggests the role of Cxcl12 secreted by hucMSCs in the treatment of lipopolysaccharide-acute lung injury

Acute respiratory distress syndrome (ARDS) is a clinical syndrome characterized by a high mortality rate, and its treatment is relatively straightforward. The application of human umbilical cord mesenchymal stem cells (hucMSCs) for the treatment of ARDS has emerged as a novel therapeutic approach and has been the subject of extensive research. In this study, a mouse model of acute lung injury (ALI) was established, and hucMSCs were administered via tail vein injection to investigate the pathogenesis of ARDS and the protein alterations following hucMSC treatment. Data-independent acquisition (DIA) was employed for the proteomic analysis of lung tissue, which included the identification of differentially expressed proteins (DEPs) and their associated pathways. The relevant DEPs identified in the lung tissues of the three groups of mice included Arid5a, Mrpl4, Cxcl12, and Rnf121 (P <0.05). Silencing the expression of Cxcl12 in hucMSCs could significantly inhibit the therapeutic effect of hucMSCs in reducing the permeability of lung tissue and endothelial cells (P < 0.05). Additionally, the signaling pathways associated with the relevant DEPs were analyzed. The DEPs and the enriched pathways discussed herein provide valuable insights into the pathogenesis of ARDS and the potential applications of hucMSCs.

SARS-CoV-2 and UPS with potentials for therapeutic interventions

The Ubiquitin proteasome system (UPS), an essential eukaryotic/host/cellular post-translational modification (PTM), plays a critical role in the regulation of diverse cellular functions including regulation of protein stability, immune signaling, antiviral activity, as well as virus replication. Although UPS regulation of viral proteins may be utilized by the host as a defense mechanism to invade viruses, viruses may have adapted to take advantage of the host UPS. This system can be manipulated by viruses such as the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) to stimulate various steps of the viral replication cycle and facilitate pathogenesis, thereby causing the respiratory disease COVID-19. Many SARS-CoV-2 encoded proteins including open reading frame 3a (ORF3a), ORF6, ORF7a, ORF9b, and ORF10 interact with the host's UPS machinery, influencing host immune signaling and apoptosis. Moreover, SARS-CoV-2 encoded papain-like protease (PLpro) interferes with the host UPS to facilitate viral replication and to evade the host's immune system. These alterations in SARS-CoV-2 infected cells have been revealed by various proteomic studies, suggesting potential targets for clinical treatment. To provide insight into the underlying causes of COVID-19 and suggest possible directions for therapeutic interventions, this paper reviews the intricate relationship between SARS-CoV-2 and UPS. Promising treatment strategies are also investigated in this paper including targeting PLpro with zinc-ejector drugs, as well as targeting viral non-structural protein (nsp12) via heat treatment associated ubiquitin-mediated proteasomal degradation to reduce viral pathogenesis.