Overexpression of estrogen receptor GPER1 and G1 treatment reduces SARS-CoV-2 infection in BEAS-2B bronchial cells.

Gender-bias in COVID-19 severity has been suggested by clinical data. Experimental data in cell and animal models have demonstrated the role of sex hormones, particularly estrogens, in viral infections such as in COVID-19. SARS-CoV-2 uses ACE2 as a receptor to recognize host cells, and the protease TMPRSS2 for priming the Spike protein, facilitating virus entry into cells. However, the involvement of estrogenic receptors in SARS-CoV-2 infection are still being explored. Thus, in order to investigate the role of estrogen and its receptors in COVID-19, the estrogen receptors ERα, ERß and GPER1 were overexpressed in bronchial BEAS-2B cell, and then infected with SARS-CoV-2. Interestingly, the levels of ACE2 and TMPRSS2 mRNA were higher in SARS-CoV-2-infected cells, but no difference was observed in cells with estrogen receptors overexpression. GPER1 can be involved in virus infection or replication, since its higher levels reduces SARS-CoV-2 load. On the other hand, pharmacological antagonism of GPER1 enhanced viral load. Those data suggest that GPER1 has an important role in SARS-CoV-2 infection.

SARS-CoV-2 infection and replication kinetics in different human cell types: The role of autophagy, cellular metabolism and ACE2 expression.

AIMS: This study evaluated SARS-CoV-2 replication in human cell lines derived from various tissues and investigated molecular mechanisms related to viral infection susceptibility and replication. MAIN METHODS: SARS-CoV-2 replication in BEAS-2B and A549 (respiratory tract), HEK-293 T (kidney), HuH7 (liver), SH-SY5Y (brain), MCF7 (breast), Huvec (endothelial) and Caco-2 (intestine) was evaluated by RT-qPCR. Concomitantly, expression levels of ACE2 (Angiotensin Converting Enzyme) and TMPRSS2 were assessed through RT-qPCR and western blot. Proteins related to autophagy and mitochondrial metabolism were monitored in uninfected cells to characterize the cellular metabolism of each cell line. The effect of ACE2 overexpression on viral replication in pulmonary cells was also investigated. KEY FINDINGS: Our data show that HuH7, Caco-2 and MCF7 presented a higher viral load compared to the other cell lines. The increased susceptibility to SARS-CoV-2 infection seems to be associated not only with the differential levels of proteins intrinsically related to energetic metabolism, such as ATP synthase, citrate synthase, COX and NDUFS2 but also with the considerably higher TMPRSS2 mRNA expression. The two least susceptible cell types, BEAS-2B and A549, showed drastically increased SARS-CoV-2 replication capacity when ACE2 was overexpressed. These modified cell lines are relevant for studying SARS-CoV-2 replication in vitro. SIGNIFICANCE: Our data not only reinforce that TMPRSS2 expression and cellular energy metabolism are important molecular mechanisms for SARS-CoV-2 infection and replication, but also indicate that HuH7, MCF7 and Caco-2 are suitable models for mechanistic studies of COVID-19. Moreover, pulmonary cells overexpressing ACE2 can be used to understand mechanisms associated with SARS-CoV-2 replication.