New insights into the COVID-19 pandemic: Genetic polymorphisms, role of SLC6 amino acid transporters, renal aspects and therapeutic perspectives

This project has been designed to aid deciphering biological and pharmaceutical aspects of the SARS-CoV-2 virus pandemic. As the pandemic progresses, it becomes apparent that there are large variations in clinical outcomes among patients, with significant country differences. Besides risk factors such as age, diabetes, arterial hypertension, cardiovascular disease, lung disease and chronic kidney disease, genetic variants in the angiotensin-converting enzyme 2 gene (ACE2), which encodes the virus receptor, the TMPRSS2 gene encoding the protease which cleaves the viral spike proteins, and the ACE2-associated amino acid transporter gene SLC6A15, likely affect SARS-CoV-2 infection and the risk of developing severe COVID-19 clinical manifestation. Using a combination of biochemical assays such as micro-scale thermophoresis (MST) to determine SARS-CoV-2 receptor binding domain (RBD) binding affinity to ACE2 and the SARS-CoV-2 pseudovirus entry assay to reveal viral load, we propose to clarify the roles of specific allelic variants of these genes in conferring COVID-19 severity, including their gender relevance and to screen for blockers of viral susceptibility as hit/lead compounds for the development of novel treatment strategies. The Specific Aims of our proposal are as follows: 1) Biochemical investigation of the effects of genetic variants of host cell targets such as ACE2, TMPRSS2 and SLC6 family members on SARS-CoV-2 RBD binding affinities and infection susceptibility; 2) investigation of the association of amino acid transporters of the SLC6 family (SLC6A14, SLC6A15 and SLC6A19) with ACE2 in lung, intestine and kidney epithelial cells and examination of their effects on SARS-CoV-2 infection; 3) screening preselected target-focused compound libraries using MST, looking for ligands that prevent SARS-CoV-2 binding; and 4) final validation of hit/lead compounds and findings on genetic polymorphisms. We expect that this project will provide straightforward new deliverables that fit in well with the goals of this NRP 78 COVID-19 Call.