Fig. 4: Omicron S1 protein distinguished from its 2019-nCov counterpart both biophysically and functionally.
From: SuPAR mediates viral response proteinuria by rapidly changing podocyte function
a–d S1 protein binding affinity as indicated by surface plasmon resonance assays. As shown, S1 protein was immobilized onto a CM5 sensor chip, while αvβ3 integrin or ACE2 was applied as an analyte in a series of increasing concentrations. Calculation of KD value indicates that 2019-nCov S1 protein bound more tightly to ACE2 (a) and αvβ3 integrin (c), as compared to Omicron S1 protein (b, d). e, f The effects of S1 protein on cultured human podocytes. Fully differentiated human podocytes were treated for 16 h before harvest for immunofluorescence staining and imaging (n = 5 biological replicates). 2019-nCov but not Omicron S1 protein enhanced ACE2 expression in human podocytes (e). 2019-nCov but not Omicron S1 protein induced αvβ3 integrin activity in human podocytes, as indicated by AP5 (an antibody specific for αvβ3 integrin activation) immunostaining (f). Notably, P < 0.01 for 2019-nCov S1 compared to Omicron S1 in both (e, f). MFI mean fluorescence intensity. Data are presented as mean ± SD. The analyses were conducted with two-way analysis of variance with Tukey’s multiple comparisons test. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.
