Genomics-guided identification of potential modulators of SARS-CoV-2 entry proteases, TMPRSS2 and Cathepsins B/L

Abstract The entry of SARS-CoV-2 into host cells requires the activation of its spike protein by host cell proteases. The serine protease, transmembrane serine protease 2 (TMPRSS2) and cysteine proteases, cathepsins B, L (CTSB/L) activate spike protein and enabling SARS-CoV-2 entry to the host cell through two completely different and independent pathways. Given that the uncertainty of how SARS-CoV-2 infects and kills, the need for a deep understanding of SARS-CoV-2 biology is imperative. Herein, we performed genomic-guided meta-analysis to identify upstream regulatory elements altering the expression of TMPRSS2 and CTSB/L genes. Further, drugs and medicinal compounds were identified based on their effects on gene expression signatures of the modulators of TMPRSS2 and CTSB/L genes. Using this strategy, estradiol and retinoic acid have been identified as putative SARS-CoV-2 alleviation agents. Further, we analysed drug-gene and gene-gene interaction network using 332 human targets of SARS-CoV-2 proteins. The network results indicate that out of 332 human proteins, estradiol interacts with 135 (41%) and retinoic acid interacts with 40 (12%) proteins. Interestingly, a combination of both estradiol and retinoic acid interacts with 153 (46%) of human proteins acting as SARS-CoV-2 targets and affect the functions of nearly all of the SARS-CoV-2 viral proteins, indicating the therapeutic benefits of drug combination therapy. Finally, molecular docking analysis suggest that both the drugs binds to TMPRSS2 and CTSL with the nanomolar to low micromolar affinity. This study, for the first time, reports the molecules like estradiol and retinoic acid as candidate drugs against both the host proteases, TMPRSS2 and CTSB/L. We here thus suggest that these antiviral drugs alone or in combination can simultaneously target both the entry pathways and thus can be considered as a potential treatment option for COVID-19.