Targeting ATP2B1 impairs PI3K/Akt/Fox-O3 signaling and reduces SARS-COV-2 replication in vivo.

ATP2B1 is a known regulator of calcium (Ca2+) cellular export and homeostasis. Diminished levels of extra- or intra-cellular Ca2+ content have been suggested to block SARS-CoV-2 replication. Here, we demonstrate that a newly nontoxic caloxin-derivative compound (PI-7) inhibits ATP2B1, reduces the extra- and intra-cellular Ca2+ levels and impairs SARS-CoV-2 replication and propagation (VOCs: Delta and Omicron 2), as also measured by inhibition of syncytia in vitro. Furthermore, a FOXO3 transcriptional site of regulation of expression at the 5 end of the ATP2B1 locus, together with a rare homozygous intronic variant in the ATP2B1 locus (rs11337717; chr12:89643729, T>C), are shown to be associated with severity of COVID19 (symptomatic versus asymptomatic patients). Here, we identify the mechanism of action during SARS-CoV-2 infection, which involves the PI3K/Akt signaling pathway, inactivation of FOXO3 (i.e., phosphorylation), and inhibition of transcriptional control of both membrane and reticulum Ca2+ pumps (ATP2B1 and ATP2A1 [i.e., SERCA1], respectively). The pharmacological action of compound PI-7 on sustaining both ATP2B1 and ATP2A1 expression reduces the intracellular cytoplasmic Ca2+ pool and thus negatively influences SARS-CoV-2 replication and propagation. As compound PI-7 shows a lack of toxicity, its prophylactic use as a therapy against the COVID19 pandemic is here proposed. In briefDe Antonellis et al. shows the importance of the Ca2+ channel pump ATP2B1 in the regulation of extracellular and intracellular Ca2+ levels that positively influence SARS-CoV-2 replication in human cells. Our study identifies the mechanism of action of SARS-CoV-2 in the regulation of the expression of ATP2B1 and ATP2A1 loci during infection via FOXO3 transcriptional factor. Furthermore, a small caloxin-derivative molecule (compound PI-7) can inhibit ATP2B1 activity, thus resulting in SARS-CoV-2 impairment. In further support, we have identified a genetic variant within the noncoding upstream region of ATP2B1 in symtomatic patients affected by severe COVID19, thus indicating this polymorphism as a genetic predisposition factor to SARS-CoV-2 infection. HighlightsO_LIAn anti-viral model of network of action for ATP2B1 against SARS-CoV-2 at the intracellular level that involves the PI3K/Akt signaling pathway, inactivation (i.e., phosphorylation) of FOXO3 and its transcriptional control, and inhibition of both membrane and reticulum Ca2+ pumps (i.e., ATP2B1, ATP2A1, respectively). C_LIO_LIA new drug and its lack of toxicity "compound PI-7", thus envisioning both preventive and therapeutic applications in patients with COVID-19. C_LIO_LIThe specificity of action in the context of Ca2+ homeostasis is one of the strategies that coronaviruses (including SARS-CoV-2 and any new VOC, including Omicron 2) use to infect host cells and promote organ dysfunction. C_LIO_LITherapeutic applications for compound PI-7 against all other viruses belonging to the Coronoviridae family (e.g., SARS-CoV, MERS-CoV), and against the main families of positive sense ssRNA viruses from other hosts (e.g., Nidovirales), as these are all Ca2+ dependent. C_LIO_LIIdentification of a rare homozygous intronic variant in the ATP2B1 locus (rs11337717; chr12:89643729, T>C) that is associated with severity of COVID19 (i.e., symptomatic versus asymptomatic patients). This variant can be used as a marker to identify those patients that might show severe COVID19 following their SARS-COV-2 infection. C_LI