The receptor-binding domain (RBD) of the severe acute respiratory syndrome coronavirus 2s pike (S) protein playsacentral role in mediating the first step of virus infection to cause disease:v irus binding to angiotensin-converting enzyme 2( ACE2) receptors on human host cells.T herefore, S/RBD is an ideal target for blocking and neutralization therapies to prevent and treat coronavirus disease 2019 (COVID-19). Using at arget-based selection approach, we developed oligonucleotide aptamers containing ac onserved sequence motif that specifically targets S/RBD.S ynthetic aptamers had high binding affinity for S/RBD-coated virus mimics (K D % 7nM) and also blocked interaction of S/RBD with ACE2 receptors (IC 50 % 5nM). Importantly,a ptamers were able to neutralizeSprotein-expressing viral particles and prevent host cell infection, suggesting apromising COVID-19 therapys trategy.
Translation is a fundamental cellular process, and its dysregulation can contribute to human diseases such as cancer. During translation initiation the eukaryotic initiation factor 2 (eIF2) forms a ternary complex (TC) with GTP and the initiator methionyl-tRNA (tRNAi), mediating ribosomal recruitment of tRNAi. Limiting TC availability is a central mechanism for triggering the integrated stress response (ISR), which suppresses global translation in response to various cellular stresses, but induces specific proteins such as ATF4. This study shows that OLA1, a member of the ancient Obg family of GTPases, is an eIF2-regulatory protein that inhibits protein synthesis and promotes ISR by binding eIF2, hydrolyzing GTP, and interfering with TC formation. OLA1 thus represents a novel mechanism of translational control affecting de novo TC formation, different from the traditional model in which phosphorylation of eIF2α blocks the regeneration of TC. Depletion of OLA1 caused a hypoactive ISR and greater survival in stressed cells. In vivo, OLA1-knockdown rendered cancer cells deficient in ISR and the downstream proapoptotic effector, CHOP, promoting tumor growth and metastasis. Our work suggests that OLA1 is a novel translational GTPase and plays a suppressive role in translation and cell survival, as well as cancer growth and progression.
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