Fig. 1.

S protein increases ACE2 expression in pericytes in a dose- and time-dependent manner. A) Western blot analysis shows that ACE2 expression in human brain vascular pericytes rapidly increases 6 h after exposure to 5 nM of S protein, reaching a peak at 15 nM. B) Western blot analysis shows that ACE2 expression in brain pericytes remains elevated 24 h after exposure to 10 nM of S protein compared to vehicle. C) XTT cell viability assay shows that exposure to 15 nM of S protein for 6 h attenuates the survival of brain pericytes. D) XTT cell viability assay shows that prolonged exposure to S protein for 24 h further attenuates the survival of brain pericytes. Data are mean ± SEM (n = 3 independent experiments/ condition; XTT cell viability assay n = 12 wells/ condition). *P < 0.05/ **P < 0.01 compared with vehicle-treated pericytes (two-tailed unpaired t-test). Vehicle, ddH₂O; 6H, 6  hours; 24H, 24  hours; XTT, 2/3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide.