Biology subjects

Okura, T.

Publications and source records attributed to Okura, T..

4 recordsLinked to original sources

bioRxiv2025

Functional analysis of promoter element 2 within the viral polymerase gene of an emerging paramyxovirus, Sosuga virus

Paramyxovirus genomes carry bipartite promoters at the 3 ends of both their genome and antigenome, thereby initiating RNA synthesis, which requires the viral polymerase to recognize two elements: the primary promoter element 1 (PE1) and the secondary promoter element 2 (PE2). We have previously shown that the antigenomic PE2 (agPE2) in many viruses in the Rubulavirinae subfamily is located within the coding region of the viral RNA polymerase L gene. Sosuga virus (SOSV), belonging to the Rubulavirinae subfamily, is highly pathogenic to humans, thus necessitating high-level containment facilities for infectious virus research. The use of a minigenome system permits studies of viral RNA synthesis at lower biosafety levels. Because minigenomes of negative-strand RNA viruses generally comprise only the untranslated regions, agPE2 within the L coding region--such as those found in Rubulavirinae like SOSV--are typically omitted. However, generating an SOSV minigenome that retains agPE2 led to a pronounced increase in activity, enabling a detailed examination of the role of agPE2 in SOSV replication. In many Rubulavirinae, the agPE2 not only acts as a promoter but also encodes part of the L protein, resulting in a distinct motif at the C-terminus of the L protein. We have further shown that this motif is preserved even in Rubulavirinae that no longer contain the agPE2 within the L gene. ImportanceParamyxoviruses are classified into three major subfamilies: Orthoparamyxovirinae, Avulavirinae and Rubulavirinae. All paramyxovirus genomes and antigenomes possess bipartite promoters, comprising two elements: promoter element 1 (PE1) at the 3 end and promoter element 2 (PE2) located internally. We previously revealed that, in many Rubulavirinae, the antigenomic PE2 lies within the coding region of the viral RNA polymerase L gene. In this study, we used Sosuga virus, a member of the Rubulavirinae subfamily, to elucidate the role of antigenomic PE2 in viral replication. Because the PE2 region encodes part of the L protein, its presence leads to a distinctive motif at the C-terminus of L protein. Notably, this motif is conserved in all Rubulavirinae, including those that do not harbor the antigenomic PE2 within their L gene, indicating its importance in viral propagation.

microbiology↗

bioRxiv2024

Exploring Organ-Specific Extracellular Vesicles in Metabolic Improvements Following Bariatric Surgery in Adolescents with Obesity

Aims/hypothesisVertical sleeve gastrectomy (VSG) leads to significant metabolic improvements, though the underlying molecular mechanisms are not yet fully understood. Emerging evidence suggests that small extracellular vesicles (sEVs) contribute to metabolic improvements post-VSG; however, it is still unclear which organ-specific sEV correlate with various metabolic parameters and how they exert these effects. The study aimed to establish the role of organ-specific sEVs in the metabolic improvements associated with VSG. MethodsDemographic, anthropometric, and blood samples were collected pre-VSG and 3- and 6-month post-VSG in adolescents with obesity. Blood samples were utilized to measure metabolic parameters and to isolate sEVs. sEV RNAs were analyzed via small RNA sequencing then bioinformatics analyses. ResultsA significant reduction in mRNA cargo from liver-specific genes was observed post- VSG, whereas adipose tissue- or skeletal muscle-specific genes showed no such reduction. Liver-derived RNA correlated with BMI, leptin, and resistin, while adipose-derived RNA correlated with leptin. Analysis of delta values (post-minus pre-surgery) revealed that adipose-derived RNA cargo correlated with markers of liver damage and HOMA-IR, whereas liver-derived RNA cargo correlated with BCAAs. ConclusionsVSG modulates the EV system in the liver and adipose tissue. Liver-derived sEVs appear to regulate adipose metabolism, while adipose-derived sEVs are associated with liver function, suggesting a dynamic crosstalk between these tissues through sEVs that shapes systemic metabolic outcomes. Research in ContextO_ST_ABSWhat is already known about this subject?C_ST_ABS- Vertical sleeve gastrectomy (VSG) is the most performed bariatric surgery, leading to significant metabolic improvements. - Small extracellular vesicles (sEVs) and their RNA cargo play a crucial role in metabolic regulation. - Levels of branched-chain amino acids (BCAAs), which are known metabolic regulators, decrease following bariatric surgery. What is the key question?- How do sEVs, BCAA and other metabolic molecules interact to drive the significant metabolic improvements observed after VSG? What are the new findings?- The levels of liver-specific RNA cargo in sEVs decrease after VSG and are correlated with BMI and leptin levels at 6 months post-surgery, suggesting a potential role for liver-specific RNA cargo in the metabolic benefits associated with VSG. - Changes in BCAA levels from baseline to 6 months post-surgery correlate with changes in liver-specific RNA cargo in sEVs, indicating liver-specific RNA cargo in sEVs may influence metabolic parameters through BCAA modulation. - Changes in the level of adipose-specific RNA cargo in sEVs from baseline to 6 month post-surgery correlate with changes HOMA-IR and ALT levels. How might this impact on clinical practice in the foreseeable future?The study identifies liver- and adipose-derived sEV RNA cargo as potential targets for non-invasive therapies that could replicate the metabolic benefits of VSG. While further investigation is needed, these findings suggest a tentative alternative for adolescents facing obesity who may be ineligible or reluctant to undergo bariatric surgery.

cell biology↗

bioRxiv2024

Rapid neutralizing assay for circulating H5N1 influenza virus in dairy cows

A rapid and safe neutralization assay is required for emerging highly pathogenic avian influenza viruses, including the H5N1 subtype, which was recently found in cows. Herein, we report a novel neutralization assay using HiBiT-tagged virus-like particles (hiVLPs). Our hiVLP-based neutralization test demonstrated a higher quantitative value and shorter assay time than conventional methods. We used this assay to evaluate whether the neutralizing antibodies induced by the candidate vaccine virus (NIID-002) were cross-reactive with cow-derived H5N1. Our results suggest that the circulating H5N1 virus in cows shares antigenic characteristics with NIID-002, providing significant implications for the development and preparation of vaccines.

microbiology↗

bioRxiv2023

General remarks of the secondary promoter element regulating the genome replication of paramyxo- and filoviruses

Paramyxo- and filovirus genomes are equipped with bipartite promoters at their 3 ends to initiate RNA synthesis. The two elements, the primary promoter element 1 (PE1) and the secondary promoter element 2 (PE2), are separated by a spacer region that must be precisely a multiple of six nucleotides, indicating these viruses are related to the "rule of six". However, our knowledge of PE2 has been limited to a narrow spectrum of virus species. In this study, a comparative analysis of 1,647 paramyxoviral genomes from a public database revealed that the paramyxovirus PE2 can be clearly categorized into two distinct subcategories: one marked by C repeats at every six bases (exclusive to the subfamily Orthoparamyxovirinae), and another characterized by CG repeats every six bases (observed in the subfamilies Avulavirinae and Rubulavirinae). This unique pattern collectively mirrors the evolutionary lineage of these subfamilies. Furthermore, we showed that the PE2 of the Rubulavirinae, with the exception of mumps virus, serves as part of the gene-coding region. This may be due to the fact that the Rubulavirinae is the only paramyxovirus that cannot propagate without RNA editing occurring. Zaire ebolavirus has eight sequential uracil (U) repeats every six bases within its genomic promoter. We showed that a minimum of four sequential U-containing hexamer repeats is imperative for genome replication. This discovery led to the identification of such quadruplet U-containing hexamer repeats within the genomic and antigenomic promoters of other viruses within the family Filoviridae. SignificanceThe genomic intricacies of paramyxo- and filoviruses are highlighted by the bipartite promoters--PE1 and PE2--at their 3 termini. The spacer region between these elements follows the "rule of six", crucial for genome replication. By a comprehensive analysis of paramyxoviral genome sequences, we identified distinct subcategories of PE2 based on C and CG repeats that were specific to Orthoparamyxovirinae and Avulavirinae/Rubulavirinae, respectively, mirroring their evolutionary lineages. Notably, the PE2 of Rubulavirinae is integrated in the gene-coding region, a unique trait potentially linked to its complete dependence on RNA editing for virus growth. This study also focused on the PE2 sequences in filovirus genomes. In filoviruses, four consecutive U-containing hexamer repeats appeared to be critical for their genome replication.

microbiology↗