Biology subjects

Murray, J. T.

Publications and source records attributed to Murray, J. T..

3 recordsLinked to original sources

bioRxiv2024

SARS-CoV-2 EndoU-ribonuclease regulates RNA recombination and impacts viral fitness.

Coronaviruses (CoVs) maintain large RNA genomes that frequently undergoes mutations and recombination, contributing to their evolution and emergence. In this study, we find that SARS-CoV-2 has greater RNA recombination frequency than other human CoVs. In addition, coronavirus RNA recombination primarily occurs at uridine (U)-enriched RNA sequences. Therefore, we next evaluated the role of SARS-CoV-2 NSP15, a viral endonuclease that targets uridines (EndoU), in RNA recombination and virus infection. Using a catalytically inactivated EndoU mutant (NSP15H234A), we observed attenuated viral replication in vitro and in vivo. However, the loss of EndoU activity also dysregulated inflammation resulting in similar disease in vivo despite reduced viral loads. Next-generation sequencing (NGS) demonstrated that loss of EndoU activity disrupts SARS-CoV-2 RNA recombination by reducing viral sub-genomic message but increasing recombination events that contribute to defective viral genomes (DVGs). Overall, the study demonstrates that NSP15 plays a critical role in regulating RNA recombination and SARS-CoV-2 pathogenesis.

microbiology↗

bioRxiv2024

Targeting of PTP4A3 overexpression sensitises HGSOC cells towards chemotherapeutic drugs.

Of all the gynecologic malignancies, Ovarian cancer (OC) has the highest mortality rate, partly attributable to its propensity for chemotherapy resistance. The most common sub-type of OC is serous, of which High-Grade Serous Ovarian Cancer (HGSOC) is the most lethal sub-type. Elevated expression of Protein Tyrosine Phosphatase 4 A3 (PTP4A3) is implicated in tumour cell invasion and metastasis, by upregulating the PI3K/Akt/mTORC1 axis. Previously we reported PTP4A3 increased the survival of non-serous OC cells in vitro by activating the autophagy pathway. The present study focused on understanding the impact of PTP4A3 on cell growth, proliferation, and autophagy in HGSOC cells. In particular, we sought to understand whether targeting PTP4A3 in cancer cells that overexpress this phosphatase would sensitise HGSOC cells to existing chemotherapeutic drugs. We report that shRNA-mediated gene silencing of PTP4A3 resulted in the upregulation of compensatory mechanisms that may render PTP4A3 targeting redundant as a monotherapy. However, pan-PTP4A inhibition with JMS-053 overcame this. Finally, silencing of PTP4A3 expression sensitized HGSOC cells to clinically relevant chemotherapeutic drugs. Since mAb therapies targeting PTP4A3 are already in clinical trials, therapeutic targeting of PTP4A3 may have significant value in improving outcomes for those patients with HGSOC, in the clinical setting.

cancer biology↗

bioRxiv2023

Loss-of-function mutation in Omicron variants reduces spike protein expression and attenuates SARS-CoV-2 infection

SARS-CoV-2 Omicron variants emerged in 2022 with >30 novel amino acid mutations in the spike protein alone. While most studies focus on receptor binding domain changes, mutations in the C-terminus of S1 (CTS1), adjacent to the furin cleavage site, have largely been ignored. In this study, we examined three Omicron mutations in CTS1: H655Y, N679K, and P681H. Generating a SARS-CoV-2 triple mutant (YKH), we found that the mutant increased spike processing, consistent with prior reports for H655Y and P681H individually. Next, we generated a single N679K mutant, finding reduced viral replication in vitro and less disease in vivo. Mechanistically, the N679K mutant had reduced spike protein in purified virions compared to wild-type; spike protein decreases were further exacerbated in infected cell lysates. Importantly, exogenous spike expression also revealed that N679K reduced overall spike protein yield independent of infection. Although a loss-of-function mutation, transmission competition demonstrated that N679K had a replication advantage in the upper airway over wild-type SARS-CoV-2 in hamsters, potentially impacting transmissibility. Together, the data show that N679K reduces overall spike protein levels during Omicron infection, which has important implications for infection, immunity, and transmission.

microbiology↗