Biology subjects

Ooi, Y. S.

Publications and source records attributed to Ooi, Y. S..

3 recordsLinked to original sources

bioRxiv2026

An integration-free CRISPR platform for genetic dissection of respiratory virus host dependencies in human nasal epithelium

Respiratory viruses, including coronaviruses, generally initiate infection in the upper respiratory tract, where mechanistic studies of host-virus interactions require models amenable to genetic manipulation. Human nasal air-liquid interface (ALI) cultures are realistic models of the nasal epithelium, but robust CRISPR/Cas9 engineering workflows for this primary cell system have been lacking. Here, we established an integration-free CRISPR/Cas9 workflow for genetic engineering of human nasal basal cells, which are subsequently differentiated into gene-edited ALI cultures. GFP-based sorting of RNP-transfected nasal basal cells substantially increases editing, achieving knockout efficiencies of 70-90% across gene targets (B2M, SLC35A1, ACE2, and TMPRSS2). Genetic disruption of ACE2 markedly reduces infection by SARS-CoV-2 and hCoV-NL63, confirming its important role for both viruses in the human nasal epithelium. TMPRSS2 knockout substantially reduces replication of both viruses, demonstrating SARS-CoV-2 depending on TMPRSS2 in the human nasal epithelium and providing genetic evidence in primary human cell cultures that hCoV-NL63 relies on TMPRSS2. This platform enables systematic genetic perturbation in a physiologically relevant model of the primary site of respiratory virus infection, validates ACE2 and TMPRSS2 as targets for medical countermeasures against SARS-CoV-2 and hCoV-NL63, and provides a versatile approach to identify host dependency factors for both circulating and emerging respiratory viruses.

microbiology↗

bioRxiv2021

Loquacious Modulates Flaviviral RNA Replication in Mosquito Cells

Arthropod-borne viruses infect both mosquito and mammalian hosts. While much is known about virus-host interactions that modulate viral gene expression in their mammalian host, much less is known about the interactions that involve inhibition, subversion or avoidance strategies in the mosquito host. A novel RNA-Protein interaction detection assay was used to detect proteins that directly or indirectly bind to dengue viral genomes in infected mosquito cells. Membrane-associated mosquito proteins SEC61A1 and Loquacious (Loqs) were found to be in complex with the viral RNA. Depletion analysis demonstrated that both SEC61A1 and Loqs have pro-viral functions in the dengue viral infectious cycle. Co-localization and pull-down assays showed that Loqs interacts with viral protein NS3 and both full-length and subgenomic viral RNAs. While Loqs coats the entire positive-stranded viral RNA, it binds selectively to the 3 end of the negative-strand of the viral genome. In-depth analyses showed that the absence of Loqs did not affect translation or turnover of the viral RNA but modulated viral replication. Loqs also displayed pro-viral functions for several flaviviruses in infected mosquito cells, suggesting a conserved role for Loqs in flavivirus-infected mosquito cells. Author SummaryThere is a wealth of information that dictates virus-host interactions in flavivirus-infected mammalian cells, yet there is only sparse information on the mechanisms that modulate viral gene expression in the mosquito host. Using a novel RNA-protein detection assay, the interactions of SEC61A1 and Loqs with the dengue viral genome were found to have proviral functions in infected mosquito cells. In particular, Loqs forms complexes with the positive-strand of the viral RNA and the very 3 end of the negative-strand viral RNA. Further analyses showed that Loqs modulates viral RNA replication of dengue virus and gene amplification of several other flaviviral genomes. These findings argue that Loqs is an essential proviral host factor in mosquitos.

microbiology↗

bioRxiv2019

A memory of RPS25 loss drives resistance phenotypes

In order to maintain cellular protein homeostasis, ribosomes are safeguarded against dysregulation by myriad processes. Many cell types can nonetheless withstand genetic lesions of certain ribosomal protein genes, some of which are linked to diverse cellular phenotypes and human disease. However, the direct and indirect consequences from sustained alterations in ribosomal protein levels are poorly understood. To address this knowledge gap, we studied in vitro and cellular consequences that follow genetic knockout of the ribosomal proteins RPS25 or RACK1 in a human cell line, as both proteins are implicated in direct translational control. Prompted by the unexpected detection of an off-target ribosome alteration in the RPS25 knockout, we closely interrogated cellular phenotypes. We found that multiple RPS25 knockout clones display viral- and toxin-resistance phenotypes that cannot be rescued by functional cDNA expression, suggesting that RPS25 loss elicits a cell state transition. We characterized this state and found that it underlies pleiotropic phenotypes and has a common rewiring of gene expression. Rescuing RPS25 expression by genomic locus repair failed to correct for the phenotypic and expression hysteresis. Our findings illustrate how the elasticity of cells to a ribosome perturbation can drive specific phenotypic outcomes that are indirectly linked to translation.

molecular biology↗