Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title><jats:p>The COVID-19 pandemic caused by the SARS-CoV-2 virus remains a global public health crisis. Although widespread vaccination campaigns are underway, their efficacy is reduced owing to emerging variants of concern<jats:sup>1,2</jats:sup>. Development of host-directed therapeutics and prophylactics could limit such resistance and offer urgently needed protection against variants of concern<jats:sup>3,4</jats:sup>. Attractive pharmacological targets to impede viral entry include type-II transmembrane serine proteases (TTSPs) such as TMPRSS2; these proteases cleave the viral spike protein to expose the fusion peptide for cell entry, and thus have an essential role in the virus lifecycle<jats:sup>5,6</jats:sup>. Here we identify and characterize a small-molecule compound, N-0385, which exhibits low nanomolar potency and a selectivity index of higher than 10<jats:sup>6</jats:sup> in inhibiting SARS-CoV-2 infection in human lung cells and in donor-derived colonoids<jats:sup>7</jats:sup>. In Calu-3 cells it inhibits the entry of the SARS-CoV-2 variants of concern B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma) and B.1.617.2 (Delta). Notably, in the K18-human ACE2 transgenic mouse model of severe COVID-19, we found that N-0385 affords a high level of prophylactic and therapeutic benefit after multiple administrations or even after a single administration. Together, our findings show that TTSP-mediated proteolytic maturation of the spike protein is critical for SARS-CoV-2 infection in vivo, and suggest that N-0385 provides an effective early treatment option against COVID-19 and emerging SARS-CoV-2 variants of concern.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Although circumstantial evidence supports enhanced Toll-like receptor 7 (TLR7) signalling as a mechanism of human systemic autoimmune disease<jats:sup>1–7</jats:sup>, evidence of lupus-causing <jats:italic>TLR7</jats:italic> gene variants is lacking. Here we describe human systemic lupus erythematosus caused by a <jats:italic>TLR7</jats:italic> gain-of-function variant. TLR7 is a sensor of viral RNA<jats:sup>8</jats:sup>,<jats:sup>9</jats:sup> and binds to guanosine<jats:sup>10</jats:sup>–<jats:sup>12</jats:sup>. We identified a de novo, previously undescribed missense <jats:italic>TLR7</jats:italic><jats:sup><jats:italic>Y264H</jats:italic></jats:sup> variant in a child with severe lupus and additional variants in other patients with lupus. The <jats:italic>TLR7</jats:italic><jats:sup><jats:italic>Y264H</jats:italic></jats:sup> variant selectively increased sensing of guanosine and 2',3'-cGMP<jats:sup>10–12</jats:sup>, and was sufficient to cause lupus when introduced into mice. We show that enhanced TLR7 signalling drives aberrant survival of B cell receptor (BCR)-activated B cells, and in a cell-intrinsic manner, accumulation of CD11c<jats:sup>+</jats:sup> age-associated B cells and germinal centre B cells. Follicular and extrafollicular helper T cells were also increased but these phenotypes were cell-extrinsic. Deficiency of MyD88 (an adaptor protein downstream of TLR7) rescued autoimmunity, aberrant B cell survival, and all cellular and serological phenotypes. Despite prominent spontaneous germinal-centre formation in <jats:italic>Tlr7</jats:italic><jats:sup><jats:italic>Y264H</jats:italic></jats:sup> mice, autoimmunity was not ameliorated by germinal-centre deficiency, suggesting an extrafollicular origin of pathogenic B cells. We establish the importance of TLR7 and guanosine-containing self-ligands for human lupus pathogenesis, which paves the way for therapeutic TLR7 or MyD88 inhibition.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Post-transcriptional modifications have critical roles in tRNA stability and function<jats:sup>1–4</jats:sup>. In thermophiles, tRNAs are heavily modified to maintain their thermal stability under extreme growth temperatures<jats:sup>5,6</jats:sup>. Here we identified 2′-phosphouridine (U<jats:sup>p</jats:sup>) at position 47 of tRNAs from thermophilic archaea. U<jats:sup>p</jats:sup>47 confers thermal stability and nuclease resistance to tRNAs. Atomic structures of native archaeal tRNA showed a unique metastable core structure stabilized by U<jats:sup>p</jats:sup>47. The 2′-phosphate of U<jats:sup>p</jats:sup>47 protrudes from the tRNA core and prevents backbone rotation during thermal denaturation. In addition, we identified the <jats:italic>arkI</jats:italic> gene, which encodes an archaeal RNA kinase responsible for U<jats:sup>p</jats:sup>47 formation. Structural studies showed that ArkI has a non-canonical kinase motif surrounded by a positively charged patch for tRNA binding. A knockout strain of <jats:italic>arkI</jats:italic> grew slowly at high temperatures and exhibited a synthetic growth defect when a second tRNA-modifying enzyme was depleted. We also identified an archaeal homologue of KptA as an eraser that efficiently dephosphorylates U<jats:sup>p</jats:sup>47 in vitro and in vivo. Taken together, our findings show that U<jats:sup>p</jats:sup>47 is a reversible RNA modification mediated by ArkI and KptA that fine-tunes the structural rigidity of tRNAs under extreme environmental conditions.</jats:p>