Biology subjects

Kanno, T.

Publications and source records attributed to Kanno, T..

12 recordsLinked to original sources

bioRxiv2026

Pre-catalytic activation pathway of the Smc5/6 complex

The Smc5/6 complex (Smc5/6) preserves genome stability through ATP-dependent DNA organization, but the structural details that prime the complex for productive DNA engagement remain unknown. Here, we combine cryo-electron microscopy and conformational heterogeneity analysis to define the pre-catalytic activation pathway of Smc5/6. We show that in the absence of ATP and DNA, Smc5/6 exists as a heterogeneous conformational ensemble composed predominantly of two conformations termed Bridge and Cross. In the presence of DNA alone, Smc5/6 adopts a Juxtaposed conformation that brings the ATPase heads into proximity, aligning them for nucleotide engagement. With both ATP and DNA associated, Smc5/6 establishes an Engaged architecture, within which DNA stabilizes its head-associated binding cavity through local remodeling of the complex. Conformational heterogeneity analyses suggest a continuous structural transition between the Cross and Juxtaposed states, while anisotropic network modeling identifies the Bridge-Cross-Juxtaposed-Engaged sequence as the mechanically favored pathway connecting the four experimentally observed conformations. Together, these findings support a pre-catalytic conformational pathway for Smc5/6 activation and provide a structural framework for understanding how conformational heterogeneity gives rise to an activation-competent motor state.

biochemistry↗

bioRxiv2026

Development of an Ethylenediaminetetraacetic Acid-Enhanced Deep Proteomic Profiling Method for Dried Blood Spots and Its Application in Mouse Disease Models

Dried blood spots (DBS) are well-established microsamples used in clinical testing and newborn screening. However, their use in deep proteomics is hindered by highly abundant blood proteins and inefficient protein recovery from filter paper matrices. The non-targeted analysis of non-specifically DBS-absorbed proteins (NANDA) workflow partially overcomes the impact of abundant blood proteins and has enabled the identification of over 5,000 proteins from DBS samples. Nonetheless, residual abundant proteins, including hemoglobin and fibrinogen, constrain deep proteomic analysis. Therefore, this study aimed to evaluate the effects of the metal chelator ethylenediaminetetraacetic acid (EDTA) on the depth of DBS proteomic analysis. An optimized EDTA-enhanced NANDA protocol that incorporated a 100 mM EDTA wash step was compatible with standard DBS collection procedures and required no modification of current clinical workflows, markedly enhancing the depletion of abundant proteins and facilitating its potential use in clinical and translational settings. When combined with Orbitrap Astral data-independent acquisition mass spectrometry, this approach enabled the single-shot identification of more than 7,000 proteins from DBS samples; to the best of our knowledge, this represents the deepest proteome coverage reported to date, and the workflow further supported high-throughput and highly reproducible analyses. Additionally, its application to mouse disease models revealed disease-specific systemic immune signatures from minimal blood volumes. Collectively, these results establish EDTA-enhanced NANDA as a practical and scalable workflow that overcomes longstanding limitations of DBS proteomics, thereby enabling deep, high-throughput, minimally invasive proteomic profiling across diverse biological and experimental contexts.

molecular biology↗

bioRxiv2026

Population-scale Y chromosome assemblies reveal recurrent remodeling within constrained architectures

The human Y chromosome is among the most structurally dynamic chromosomes in the human genome, yet much of its diversity remains unresolved because of extensive palindromes, ampliconic gene families, satellite-rich heterochromatin and large segmental duplications. What remained unclear was how these diverse forms of variation fit together across the full chromosome, how often similar structures recur in different lineages, and which aspects of organization remain constrained despite rapid sequence turnover. Here, we generated and analyzed 142 nearly complete human Y chromosome assemblies from 17 major haplogroups spanning approximately 180,000 years of evolution, creating a population-scale resource for studying Y chromosome biology and diversity. These assemblies show that structural change on the Y chromosome is recurrent but constrained, even in its most repetitive regions. In the fertility-associated azoospermia factor c (AZFc) region, recurrent inversions, deletions, and complex rearrangements generate a limited repertoire of structural haplotypes. Multicopy ampliconic gene families follow distinct evolutionary paths: DAZ paralogues differ in structural constraint, RBMY evolves within a modular array, and TSPY copy number varies mainly through local expansion and contraction. The centromere and Yq12 heterochromatin vary greatly in size but retain a stable higher-order organization, including a single hypomethylated centromeric core and conserved Yq12 repeat composition and orientation. Methylation across palindromic and ampliconic regions is likewise structured by repeat class, copy order and local architecture. Together, these results provide a population-scale resource for the human Y chromosome and show that its rapid structural evolution is repeatedly funneled into a limited set of architectural outcomes.

genomics↗

bioRxiv2024

Symmetry of loop extrusion by dimeric SMC complexes is DNA-tension-dependent

Structural maintenance of chromosome (SMC) complexes organize and regulate genomes by extruding DNA loops. During loop extrusion, DNA can be reeled into the growing loop from one or both sides, generating distinct extrusion directionality states whose physical basis remains unclear. Here, we combine single-molecule analysis and molecular dynamics simulations to investigate loop extrusion directionality across SMC complexes. We show that dimeric Smc5/6 and Wadjet predominantly perform two-sided loop extrusion during initial loop growth, whereas monomeric condensin exhibits one-sided extrusion, consistent with a relationship between stoichiometry and extrusion directionality. Surprisingly, however, cohesin predominantly exhibits one-sided extrusion despite functioning as a dimeric complex. Notably, dimeric Smc5/6 and Wadjet progressively transition from two-sided to one-sided extrusion as loop growth matures. Simulations and force-dependent analysis reveal that loop extrusion directionality is governed by a tension-dependent transition in dimeric motors. Increasing DNA tension erodes two-sided extrusion near the motor stalling force, driving a tug-of-war regime in which competing motors transiently dominate one another. This transition promotes one-sided extrusion during mature Smc5/6 and Wadjet-mediated loop extrusion and places cohesin, which has a comparatively low stalling force ([~]0.1 pN), constitutively near this regime. Together, our findings establish loop extrusion directionality as a dynamic emergent property governed by SMC stoichiometry, DNA tension, and stochastic motor competition.

biophysics↗

bioRxiv2024

Identification and functional categorization of the most stably and most variably expressed genes and retained introns in Arabidopsis thaliana seedlings

We used a large, uniform, RNA-seq dataset to investigate the stability of gene expression and intron retention in Arabidopsis thaliana seedlings. Functional classification of the most stably and most variably expressed genes was determined by GO enrichment analyses. Many variably expressed genes encoded proteins involved in photosynthesis and chloroplast structure, likely reflecting their sensitivity to changeable light intensities, and in stress responses, which allow plants to cope with environmental challenges. As revealed by GO enrichment analysis, the most stably expressed genes were involved in protein, lipid and vesicle trafficking, suggesting that fluctuations in expression of these genes are suboptimal for normal seedling development. GO analyses of genes containing either usually retained or usually spliced introns revealed no consistent enrichments for any specific functional categories. However, highly retained introns were often located in the first or last position, which may contain 5 and 3 UTRs necessary for transcriptional regulation and mRNA transport and stability. Conversely, usually spliced introns were more frequently located in internal portions of pre-mRNAs, indicating that reliable splicing in coding regions is needed to prevent the formation of premature stop codons. The large RNA-seq dataset we generated can be useful for investigating additional aspects of gene expression and pre-mRNA splicing in Arabidopsis seedlings and sets a precedent for future large scale transcriptome analyses.

plant biology↗

bioRxiv2024

Large ungulates will be present in most of Japan by 2050 owing to natural expansion and human population shrinkage

The aims of this study were to elucidate factors contributing to the expansion of the distributions of sika deer and wild boar in Japan and to predict the expansion of their distributions by 2025, 2050, and 2100. A site occupancy model was constructed using information on species distribution collected by the Ministry of the Environment in 1978, 2003, 2014, and 2018, days of snow cover, forested and road areas, elevation, human population, and distance from occupied grid cells as covariates to calculate the probability of distribution change. Factors contributing to distribution expansion were elucidated and distribution expansion was predicted. Distance from occupied grid cells had the strongest influence on distribution expansion, followed by the inherent ability of each species to expand its distribution. For sika deer, human population had a strong negative effect and elevation and number of days of snow cover were important. For wild boar, forest area and elevation had high importance. Predictions of future distribution showed that both species will be distributed over 90% of Japan by 2050 and over 100% by 2100.

ecology↗

bioRxiv2023

Loop-extruding Smc5/6 organizes transcription-induced positive DNA supercoils

The Structural Maintenance of Chromosome (SMC) protein complexes cohesin, condensin and the Smc5/6 complex (Smc5/6) are essential for chromosome function. At the molecular level, these complexes fold DNA by loop extrusion. Accordingly, cohesin creates chromosome loops in interphase, and condensin compacts mitotic chromosomes. However, the role of Smc5/6s recently discovered DNA loop extrusion activity is unknown. Here, we uncover that Smc5/6 associates with transcription-induced positively supercoiled chromosomal DNA at cohesin-dependent chromosome loop boundaries. Mechanistically, single-molecule imaging reveals that dimers of Smc5/6 specifically recognize the tip of positively supercoiled DNA plectonemes, and efficiently initiates loop extrusion to gather the supercoiled DNA into a large plectonemic loop. Finally, Hi-C analysis shows that Smc5/6 links chromosomal regions containing transcription-induced positive supercoiling in cis. Altogether, our findings indicate that Smc5/6 controls the three-dimensional organization of chromosomes by recognizing and initiating loop extrusion on positively supercoiled DNA.

molecular biology↗

bioRxiv2022

Intranasal vaccination induced cross-protective secretory IgA antibodies against SARS-CoV-2 variants with reducing the potential risk of lung eosinophilic immunopathology

To control the coronavirus disease 2019 (COVID-19) pandemic, there is a need to develop vaccines to prevent infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. One candidate is a nasal vaccine capable of inducing secretory IgA antibodies in the mucosa of the upper respiratory tract, the initial site of infection. However, regarding the development of COVID-19 vaccines, there is concern about the potential risk of inducing lung eosinophilic immunopathology as a vaccine-associated enhanced respiratory disease as a result of the T helper 2 (Th2)-dominant adaptive immune response. In this study, we investigated the protective effect against virus infection induced by intranasal vaccination of recombinant trimeric spike protein derived from SARS-CoV-2 adjuvanted with CpG oligonucleotides, ODN2006, in mouse model. The intranasal vaccine combined with ODN2006 successfully induced not only systemic spike-specific IgG antibodies, but also secretory IgA antibodies in the nasal mucosa. Secretory IgA antibodies showed high protective ability against SARS-CoV-2 variants (Alpha, Beta and Gamma variants) compared to IgG antibodies in the serum. The nasal vaccine of this formulation induced a high number of IFN-{gamma}-secreting cells in the draining cervical lymph nodes and a lower spike-specific IgG1/IgG2a ratio compared to that of subcutaneous vaccination with alum as a typical Th2 adjuvant. These features are consistent with the induction of the Th1 adaptive immune response. In addition, mice intranasally vaccinated with ODN2006 showed less lung eosinophilic immunopathology after viral challenge than mice subcutaneously vaccinated with alum adjuvant. Our findings indicate that intranasal vaccine adjuvanted with ODN2006 could be a candidate that can prevent the infection of antigenically different variant viruses, reducing the risk of vaccine-associated enhanced respiratory disease.

microbiology↗

bioRxiv2022

The Smc5/6 complex is a DNA loop extruding motor

Structural Maintenance of Chromosomes (SMC) protein complexes are essential for the spatial organization of chromosomes. While cohesin and condensin organize chromosomes by extruding DNA loops, the molecular functions of the third eukaryotic SMC complex, Smc5/6, remain largely unknown. Using single-molecule imaging, we reveal that Smc5/6 forms DNA loops by extrusion. Upon ATP-hydrolysis, Smc5/6 symmetrically reels DNA into loops at a force-dependent rate of 1 kilobase pairs per second. Smc5/6 extrudes loops in the form of a dimer, while monomeric Smc5/6 unidirectionally translocate along DNA. We also find that Nse5 and Nse6 (Nse5/6) subunits act as negative regulators of Smc5/6-mediated loop initiation and stability. Our findings reveal Smc5/6s molecular functions, and establish loop extrusion as a conserved mechanism among eukaryotic SMC complexes. One-Sentence SummarySmc5/6 is a DNA-loop-extruding motor, establishing loop extrusion as a conserved mechanism among eukaryotic SMC complexes.

biophysics↗

bioRxiv2018

Reverse transcription-PCR using a Primer Set Targeting the 3D Region Detects Foot-and-Mouth Disease Virus with High Sensitivity

Because foot-and-mouth disease (FMD) has the potential to spread extensively, methods used for its diagnosis must be rapid and accurate. Therefore, reverse transcription-PCR (RT-PCR) plays an important diagnostic role. Here we designed the primer set FM8/9 to amplify 644 bases of the conserved 3D region of all seven serotypes of FMD virus (FMDV). We compared the performance of RT-PCR assays using FM8/9 with that using the primer set 1F/R targeting the 5-UTR described in the manual of the World Organization for Animal Health. The detection limits of the RT-PCR assays were determined for 14 strains representing all serotypes. Compared with the sensitivities of the RT-PCR assay using 1F/R, those using FM8/9 were 101-to 104-fold higher for eight strains. To assess the validity of the methods for analyzing clinical samples, sera and saliva samples from pigs and cows infected with FMDV were collected daily and analyzed using the two PCR assays. The FM8/9 assay detected FMDV from all infected pigs and cows for longer times compared with the 1F/R assay, therefore revealing higher sensitivity for the clinical samples. Our results suggest that the FM8/9 RT-PCR assay is highly sensitive and is therefore suitable for the diagnosis of FMD.

microbiology↗

bioRxiv2018

Rifampicin or capreomycin induced remodelling of the Mycobacterium smegmatis mycolic acid layer is mitigated in synergistic combinations with cationic antimicrobial peptides

The mycobacterial cell wall affords natural resistance to antibiotics. Antimicrobial peptides (AMPs) modify the surface properties of mycobacteria and can act synergistically with antibiotics from differing classes. Here we investigate the response of Mycobacterium smegmatis to the presence of rifampicin or capreomycin, either alone or in combination with two synthetic, cationic, -helical AMPs; distinguished by the presence (D-LAK120-HP13) or absence (D-LAK120-A) of a kink-inducing proline. Using a combination of high-resolution magic angle spinning (HR-MAS) NMR of bacteria, diphenylhexatriene (DPH) fluorescence anisotropy and laurdan emission spectroscopy we show that M. smegmatis responds to challenge with rifampicin or capreomycin by substantially altering its metabolism and, in particular, by remodelling the cell envelope. In NMR spectra of bacteria, reductions in intensity for mycolic acid lipid -(CH2)-, -CH3, R2CH-COOH, R2CH-OH and also -CH2-(CH==CH)- and -CH=CH- resonances were observed following challenge with rifampicin and capreomycin, while the latter also caused an increase in trehalose. These changes are consistent with a reduction of trehalose dimycolate and increase of trehalose monomycolate and are associated with an increase in rigidity of the mycolic acid layer observed following challenge by capreomycin but not rifampicin. Challenge with D-LAK120-A or D-LAK120-HP13 induced no or modest changes respectively in these metabolites and did not induce a significant increase in rigidity of the mycolic acid layer. Further, the response to rifampicin or capreomycin was significantly reduced when these were combined respectively with D-LAK120-HP13 and D-LAK120-A, suggesting a possible mechanism for the synergy of these combinations. The remodelling of the mycomembrane in M. smegmatis is therefore identified as an important countermeasure deployed against rifampicin or capreomycin, but this can be mitigated, and rifampicin or capreomycin efficacy potentiated, by combining with AMPs.

microbiology↗

bioRxiv2017

Self-organization of a functional human organizer by combined WNT and NODAL signalling

In amniotes, the development of the primitive streak (PS) and its accompanying \"organizer\" define the first stages of gastrulation. Despite detailed characterization in model organisms, the analogous human structures remain a mystery. We have previously shown that when stimulated with BMP4, micropatterned colonies of human embryonic stem cells (hESCs) self-organize to generate early embryonic germ layers1. Here we show that in the same type of colonies WNT signalling is sufficient to induce a PS, and WNT with ACTIVIN is sufficient to induce an organizer, as characterized by embryo-like sharp boundary formation, epithelial-to-mesenchymal transition (EMT) markers, and expression of the organizer specific transcription factor GSC. Moreover, when grafted into chick embryos, WNT and ACTIVIN treated human cells induce and contribute autonomously to a secondary axis while inducing neural fate in the host. This fulfills the most stringent functional criteria for an organizer, and its discovery represents a major milestone in human embryology.

developmental biology↗