Biology subjects

Taguwa, S.

Publications and source records attributed to Taguwa, S..

4 recordsLinked to original sources

bioRxiv2026

A versatile and stable reporter platform for human rhinovirus and other enteroviruses

Human rhinovirus (HRV), a major cause of upper respiratory infections, has increasingly been associated with lower respiratory tract disease. Although tools to investigate HRV pathogenesis are needed, they remain limited. Reporter viruses expressing fluorescent or luminescent proteins are powerful tools for analyzing viral distribution and replication; however, insertion of a reporter gene often impairs viral replication, and the inserted gene is readily lost during serial passage. To address these problems, we established a versatile and stable strategy for generating reporter HRV and other enteroviruses. The gene encoding mScarlet3, a red fluorescent protein, was inserted between the 5'UTR and VP4 gene, a site previously used in other enteroviruses but not in HRV. Optimizing the 2A cleavage sequence between mScarlet3 and VP4 yielded a reporter HRV with growth kinetics comparable to those of the wild-type virus. To improve the genetic stability of the reporter insert, we evaluated GC-content optimization of the reporter gene and relocation of the cis-acting replication element (CRE). GC-content optimization substantially improved reporter stability in both HRV-B14 and EV-A71, whereas CRE relocation provided additional stabilization in EV-A71 but not in HRV-B14, demonstrating the potential applicability of this strategy to other enteroviruses. This strategy for constructing stable reporter HRV and other enteroviruses will facilitate studies of enterovirus pathogenesis.

microbiology↗

bioRxiv2025

Establishment of a green fluorescent protein (GFP)-based reporter for picornaviral 3C proteases

Picornaviruses represent a diverse group of plus-stranded RNA viruses, many of which have been linked to severe diseases in both humans and animals. The viral 3C protease is essential for the maturation of viral proteins and the propagation of picornaviruses and, owing to its cleavage activity against multiple host proteins, is associated with the pathogenesis of picornaviruses. The picornaviral 3C protease is an ideal drug target for inhibiting viral propagation and mitigating pathogenesis; however, methodology to evaluate and compare the activity of phylogenetically diverse proteases remains lacking. To address this, herein, we propose a novel green fluorescent protein (GFP)-based reporter optimized to visualize the enzymatic activity of picornaviral 3C proteases in cells by using the conformational change of a GFP variant induced by the 3C protease, generating fluorescence emission linked to the enzymatic activity. Upon treatment of picornaviruses with a known 3C protease inhibitor, the fluorescence decreased in a dose-dependent manner, demonstrating that the signal depended on the activity of the 3C protease. The reporter system for the 3C protease can be applied to major pathogenic human picornaviruses, such as those in the genera Enterovirus, Rhinovirus, Cosavirus, Salivirus, and Kobuvirus. Furthermore, the fluorescent signal from the reporter was confirmed in various animal- derived picornaviruses, such as those from bats, rodents, and primates. Therefore, the reporter could be widely used to analyze the activity of several 3C proteases from currently prevalent picornaviruses and those that may emerge in the future. To demonstrate the flexibility of the reporter in comparing phylogenetically different proteases, the enzymatic activity of the 3C protease derived from clinical strains of enterovirus A71 (EV-A71) was tested and compared. The results showed that the amino acid residues of the 3C protease affect its activity by utilizing the reporter system. Additionally, clinical EV- A71 strains had different effects on the activity of 3C protease against host proteins. Our findings will aid in elucidating the molecular characteristics of 3C proteases among picornaviruses and developing therapeutics to mitigate the pathogenesis of these viruses.

cell biology↗

bioRxiv2022

A Comprehensive Enumeration of the Human Proteostasis Network. 1. Components of Translation, Protein Folding, and Organelle-Specific Systems

The condition of having a healthy, functional proteome is known as protein homeostasis, or proteostasis. Establishing and maintaining proteostasis is the province of the proteostasis network, approximately 2,500 genes that regulate protein synthesis, folding, localization, and degradation. The proteostasis network is a fundamental entity in biology with direct relevance to many diseases of protein conformation. However, it is not well defined or annotated, which hinders its functional characterization in health and disease. In this series of manuscripts, we aim to operationally define the human proteostasis network by providing a comprehensive, annotated list of its components. Here, we provide a curated list of 959 unique genes that comprise the protein synthesis machinery, chaperones, folding enzymes, systems for trafficking proteins into and out of organelles, and organelle-specific degradation systems. In subsequent manuscripts, we will delineate the human autophagy-lysosome pathway, the ubiquitin-proteasome system, and the proteostasis networks of model organisms.

bioinformatics↗

bioRxiv2020

Principles of dengue virus evolvability derived from genotype-fitness maps in human and mosquito cells

Dengue virus (DENV), an arbovirus infecting over 100 million annually, cycles between human and mosquito hosts1. Examining how DENV adapts to such different host environments could uncover principles of arbovirus transmission and emergence. Here we combine sequential passaging and ultra-deep sequencing to examine the sequence dynamics and fitness changes of DENV populations adapting to human and mosquito cells, identifying the contributions of beneficial and deleterious mutations in shaping the fitness landscape driving host-specific paths of viral adaptation. We find DENV phenotypic adaptation is best described by the collective fitness contributions of all the alleles present in the population. Accordingly, while increased fitness during adaptation to each host is driven by host-specific beneficial mutations, it is reduced by the consistently replenished genetic load of deleterious mutations. Of note, host-specific beneficial mutations are in discrete regions across the genome, revealing molecular mechanisms of adaptation. Some of these clusters comprise phenotypically redundant mutations that may provide evolutionary robustness to transmission bottlenecks. Our results also suggest DENV adaptation is facilitated through variation in intrinsically disordered protein regions while transmembrane and structured domains evolve under stronger biophysical constraints. Importantly, the adaptation strategies uncovered in our simple system mirror macro-evolutionary changes observed across DENV serotypes and Zika virus and may suggest general principles of evolvability in arbovirus evolution.

microbiology↗