Biology subjects

Arai, C.

Publications and source records attributed to Arai, C..

4 recordsLinked to original sources

bioRxiv2025

Spontaneous mutations in braRS and braAB and the IS1181-related deletion of vraDE genes increase the susceptibility of Staphylococcus aureus clinical isolates to epidermin

Bacteriocins, which are antimicrobial factors produced by bacteria, are expected to be candidates for a novel class of antimicrobial agents against antimicrobial-resistant bacteria, including methicillin-resistant Staphylococcus aureus. To evaluate its effectiveness, the examination of susceptibility using multiple clinical isolates is necessary. In this study, we focused on epidermin, a class I bacteriocin produced by Staphylococcus epidermidis. Among the 146 S. aureus clinical isolates, 77% did not show susceptibility to epidermin, but the susceptibility of some of the strains was significantly higher. Knowing that the two-component regulatory system BraRS affects the susceptibility to epidermin, we analyzed the inducibility of the effector gene vraD in susceptible strains and found that its ability is lost in highly susceptible strains. Some of these strains harbor frameshift or nonsense mutations in BraR, BraA and BraB. Interestingly, the vraDE genes with 35,005 bp neighboring genomic regions, including the icaRADBC and histidine biosynthesis operons, were lost in some highly susceptible strains. In addition, all the vraDE-deficient strains were CC121, and IS1181 sequences located immediately upstream and downstream of the deleted region were found in some vraDE-positive CC121 strains. The deleted region was replaced by one copy of the IS1181 sequence in vraDE-deficient strains. Subculturing of the vraDE-positive CC121 strain generated a vraDE-deficient mutant with increased susceptibility to epidermin at a rate of approximately 1%, suggesting that recombination between IS1181 sequences results in the deletion of the genomic region, including vraDE, in some CC121 strains.

microbiology↗

bioRxiv2025

Preclinical Prediction of Resistance and Optimization of Sequential Therapy for ALK-positive Lung Cancer Using Next-generation ALK Inhibitors

BackgroundAnaplastic lymphoma kinase (ALK) gene rearrangements occur in approximately 5% of non-small cell lung cancers (NSCLCs). Although ALK tyrosine kinase inhibitors provide substantial clinical benefits, acquired resistance-conferring mutations frequently emerge, leading to disease progression. Preclinical prediction of these mutations might help guide the development of more effective sequential treatment strategies prior to clinical application. ObjectiveTo predict the emergence of resistance mutations to the investigational ALK inhibitors zotizalkib (TPX-0131), gilteritinib (ASP2215), and neladalkib (NVL-655) following resistance to first-line alectinib and assess the potential of these drugs as second-line therapies. MethodsA polymerase chain reaction (PCR)-based mutagenesis system was used to introduce random mutations into ALK cDNA harboring representative alectinib-resistant mutations. Mutant libraries were expressed in Ba/F3 cells, which were exposed to each inhibitor. Drug-resistant clones were isolated, sequenced, and evaluated for drug sensitivity using viability assays and immunoblotting. ResultsSeveral resistance mutations against zotizalkib, gilteritinib, and neladalkib were identified. Sequential use of these agents effectively suppressed all predicted resistance patterns with G1202R or I1171N. ConclusionsThis PCR-based platform provides a valuable approach for anticipating resistance mutations and guiding the design of optimized sequential therapies. Zotizalkib, gilteritinib, and neladalkib might represent promising alternatives to lorlatinib as second-line treatments for ALK-positive NSCLC. Key PointsO_LIPCR-based mutation prediction system was successfully applied to fourth-generation ALK inhibitors. C_LIO_LIshowed efficacy against G1202R-positive relapses with minimal evidence of secondary resistance mutations. C_LIO_LIcombinations of gilteritinib with either neladalkib or ensartinib may sustain efficacy and delay resistance in I1171N-positive relapses. C_LI

cancer biology↗

bioRxiv2024

TOMM40-APOE chimera linking Alzheimer's highest risk genes: a new pathway for mitochondria regulation and APOE4 pathogenesis

The patho-mechanism of apolipoprotein variant, APOE4, the strongest genetic risk for late-onset Alzheimers disease (AD) and longevity, remains unclear. APOEs neighboring gene, TOMM40 (mitochondria protein transport channel), is associated with brain trauma outcome and aging-related cognitive decline, however its role in AD APOE4-independently is controversial. We report that TOMM40 is prone to transcription readthrough into APOE that can generate spliced TOMM40-APOE mRNA chimera (termed T9A2) detected in human neurons and other cells and tissues. T9A2 translation tethers APOE (normal APOE3 or APOE4) to near-full-length TOM40 that is targeted to mitochondria. Importantly, T9A2-APOE3 boosts mitochondrial bioenergetic capacity and decreases oxidative stress significantly more than T9A2-APOE4 and APOE3, and lacking in APOE4. We describe detailed interactomes of these actors that may inform about the activities and roles in pathogenesis. T9A2 uncovers a new candidate pathway for mitochondria regulation and oxidative stress-protection that are impaired in APOE4 genotypes and could initiate neurodegeneration.

cell biology↗

bioRxiv2019

U1 snRNP regulates cancer cell migration and invasion

Stimulated cells and cancer cells have widespread shortening of mRNA 3-utranslated regions (3UTRs) and switches to shorter mRNA isoforms due to usage of more proximal polyadenylation signals (PASs) in the last exon and in introns. U1 snRNA (U1), vertebrates most abundant non-coding (spliceosomal) small nuclear RNA, silences proximal PASs and its inhibition with antisense morpholino oligonucleotides (U1 AMO) triggers widespread mRNA shortening. Here we show that U1 AMO also modulates cancer cells phenotype, dose-dependently increasing migration and invasion in vitro by up to 500%, whereas U1 over-expression has the opposite effect. In addition to 3UTR length, numerous transcriptome changes that could contribute to this phenotype are observed, including alternative splicing, and mRNA expression levels of proto-oncogenes and tumor suppressors. These findings reveal an unexpected link between U1 regulation and oncogenic and activated cell states, and suggest U1 as a potential target for their modulation.

molecular biology↗