Biology subjects

Ueno, M.

Publications and source records attributed to Ueno, M..

11 recordsLinked to original sources

bioRxiv2025

GABA mediates experience-dependent regulation of myelination in the mouse visual pathway.

Myelination in the visual pathway is critical for transmitting visual information from retina to the brain. Reducing visual experience shortens myelin sheath length and slows the conduction velocity of the optic nerve. However, the mechanism underlying such experience-dependent myelination is unclear. Here, we found that closing both eyes, binocular deprivation (BD), during the juvenile period less affects the optic nerve myelination than monocular deprivation (MD) via GABA signaling. RNA-seq analysis of optic nerves from MD and BD mice revealed that GABAergic signaling is downregulated on the deprived side of MD compared to the intact side and BD. Inhibition of GABAergic signaling during the juvenile period resulted in myelin sheath shortening and excessive oligodendrocyte generation in normal mice, similar to the changes observed in MD mice. Enhancing GABAergic signaling rescued the myelin sheath shortening and excessive oligodendrocyte generation in the optic nerve of MD mice. Furthermore, we identified novel GABAergic neurons located within the optic nerve, whose neurites form belt-like presynaptic structures with the oligodendrocyte lineage cells, suggesting a potential source of the GABAergic inputs into oligodendrocytes. Our results indicate that the myelination of visual pathway is maintained by binocular visual inputs via intra-nerve GABA signaling.

neuroscience↗

bioRxiv2025

Scg2 drives reorganization of the corticospinal circuit with spinal premotor interneurons to recover motor function after stroke

Brain injuries such as stroke damage neural circuitry and lead to functional deficits. Spared motor pathways are often reorganized and contribute to functional recovery; however, the connectivity and molecular mechanisms that drive the reorganization are largely unknown. Here, we demonstrate structural and functional connectivity reformed by spared corticospinal axons after stroke and determine a key secretory protein that drives the reorganization. We first found that corticospinal axons innervate specific areas of the denervated cervical cord after stroke. Anatomical and photometric analyses reveal that the axons reconnect to premotor V2a interneurons. Kinematic analyses of forelimb movements and chemogenetic silencing reveal their contribution to motor recovery. Translated mRNA expression analyses of V2a interneurons and astrocytes in the denervated cervical cord reveal diverse transcripts upregulated in the rewiring process. In particular, a secretory protein Scg2 is upregulated by injury-induced purinergic ATP signals and rehabilitative training-induced neural activity and possesses an ability to promote axon growth via cAMP and S6 signaling. Scg2 overexpression in the denervated cervical cord enhances axon rewiring, while the Scg2 knockdown attenuates it. The present data reveal the neural substrate and molecular mechanism essential to induce reorganization and recovery of the motor system, providing fundamental therapeutic targets for CNS injuries.

neuroscience↗

bioRxiv2024

Extracellular disposal of nuclear waste by APP: a protective mechanism impaired in Alzheimer's disease

Although the amyloid beta (A{beta}) hypothesis1 has long been central to Alzheimers disease (AD) research, effective therapeutic strategies remain elusive2,3. Here we re-evaluate the functions of amyloid precursor protein (APP) and reveal its critical function in protecting against nuclear impairment-induced cell death and inflammation4,5. Overexpression of APP mitigated etoposide or lamin A knockdown-induced nuclear damage, while APP removal or mutations exacerbated these effects. Interestingly, neurons differentiated from induced pluripotent stem cells (iPSCs) exhibited similar patterns, and notably, familial AD-associated mutant APP failed to confer protection against nuclear impairment. We identify APPs interaction with a cytoplasmic structure of nuclear origin, termed "nuclear waste", and propose its role in extracellular waste disposal. Intriguingly, cells lacking APP showed impaired nuclear waste clearance, leading to abnormal cytoplasmic accumulation of the nuclear waste. Similarly, neuron-specific APP overexpression using adeno-associated virus (AAV) in mice reduced neuronal death and inflammation caused by nuclear damage. Conversely, shRNA-mediated APP exacerbated these effects, and mutant APP associated with familial AD lacked protective effects. Moreover, postmortem analysis of AD brains revealed accumulation of abnormal nuclear waste in the neurocytoplasm, irregular nuclear morphology, and reduced APP levels per neuron. Our data underscore APPs crucial role in disposing of nuclear waste, maintaining cellular homeostasis, and suggest its dysregulation as a potential contributor to AD pathogenesis. Restoring APP waste clearance in AD could be a promising target for disease-modifying therapies.

neuroscience↗

bioRxiv2022

Cerebrospinal fluid-contacting neuron tracing reveals structural and functional connectivity for locomotion in the mouse spinal cord

Cerebrospinal fluid-contacting neurons (CSF-cNs) are enigmatic mechano- or chemosensory cells lying along the central canal of the spinal cord. Recent studies in zebrafish larvae and lampreys have shown that CSF-cNs control postures and movements via spinal connections. However, the structures, connectivity, and functions in mammals remain largely unknown. Here we developed a method to genetically target mouse CSF-cNs that highlighted structural connections and functions. We first found that intracerebroventricular injection of adeno-associated virus with a neuron-specific promoter and Pkd2l1-Cre mice specifically labeled CSF-cNs. Single-cell labeling of 71 CSF-cNs revealed rostral axon extensions of over 1800 m in unmyelinated bundles in the ventral funiculus and terminated on CSF-cNs to form a recurrent circuitry, which was further determined by serial electron microscopy and electrophysiology. CSF-cNs were also found to connect with axial motor neurons and premotor interneurons around the central canal and within the axon bundles. Chemogenetic CSF-cNs inactivation reduced speed and step frequency during treadmill locomotion. Our data revealed the basic structures and connections of mouse CSF-cNs to control spinal motor circuits for proper locomotion. The versatile methods developed in this study will contribute to further understanding of CSF-cNs functions in mammals.

neuroscience↗

bioRxiv2022

Aberrant association of chromatin with nuclear periphery induced by Rif1 leads to mitotic defect and cell death.

Chromatin is compartmentalized in nuclei and its architecture and nuclear location may have impacts on chromatin events. Rif1, identified as a potent suppressor of hsk1-null mutation (defective in initiation of DNA replication) in fission yeast, recognizes G-quadruplex structures and inhibits origin firing in their 50[~]100-kb vicinity, leading us to postulate that Rif1 may generate chromatin higher-order structures inhibitory for initiation. However, effects of Rif1 on chromatin localization in nuclei have not been known. We show here that overexpression of Rif1 causes growth inhibition and eventually cell death in fission yeast. Chromatin binding activities of Rif1, but not recruitment of phosphatase PP1, are required for growth inhibitory effect. Overexpression of a PP1 binding site mutant of Rif1 does not delay S-phase, but still causes cell death, indicating that cell death is caused not by S-phase problems but by issues in other phases of cell cycle, most likely M-phase. Indeed, Rif1 overexpression generates cells with unequally segregated chromosomes. Rif1 overexpression relocates chromatin near nuclear periphery in a manner dependent on its chromatin-binding ability, and this correlates with growth inhibition and cell death induction. Thus, regulated Rif1-mediated chromatin association with nuclear periphery is important for coordinated progression of S- and M-phases.

molecular biology↗

bioRxiv2021

3,3'-Diindolylmethane induces apoptosis and autophagy in fission yeast

3,3-Diindolylmethane (DIM) is a compound derived from the digestion of indole-3-carbinol, found in the broccoli family. It induces apoptosis and autophagy in some types of human cancer. DIM extends lifespan in the fission yeast Schizosaccharomyces pombe. The mechanisms by which DIM induces apoptosis and autophagy in humans and expands lifespan in fission yeasts are not fully understood. Here, we show that DIM induces apoptosis and autophagy in log-phase cells, which is dose-dependent in fission yeast. A high concentration of DIM disrupted the nuclear envelope (NE) structure and induced chromosome condensation at an early time point. In contrast, a low concentration of DIM induced autophagy but did not disrupt NE structure. The mutant defective in autophagy was more sensitive to a low concentration of DIM, demonstrating that the autophagic pathway contributes to the survival of cells against DIM. Moreover, our results showed that the lem2 mutant is more sensitive to DIM. NE in the lem2 mutant was disrupted even at the low concentration of DIM. Our results demonstrate that the autophagic pathway and NE integrity are important to maintain viability in the presence of a low concentration of DIM. The mechanism of apoptosis and autophagy induction by DIM might be conserved in fission yeast and humans. Further studies will contribute to the understanding of the mechanism of apoptosis and autophagy by DIM in fission yeast and humans.

molecular biology↗

bioRxiv2021

Comprehensive analysis of full-length transcripts reveal aberrations of splicing variants in liver cancer

Genes generate various transcripts by alternative splicing, and these transcripts can have diverse functions. However, in most transcriptome studies, short-reads sequencing technologies (next-generation sequencers) have been used and full-length transcripts have not been observed directly. Although long-reads sequencing technologies would enable us to sequence full-length transcripts, analysis of the data is a difficult task. In the present study, we developed an analysis pipeline named SPLICE to analyze full-length cDNA sequences. Using this method, we analyzed cDNA sequences from 42 pairs of hepatocellular carcinoma (HCC) and matched non-cancerous liver with Oxford Nanopore technology. Our analysis detected 46,663 transcripts from the protein-coding genes in the HCCs and the matched non-cancerous livers, of which 5,366 (11.5 %) were novel. Comparison of expression levels identified 9,933 differentially expressed transcripts (DETs) in 4,744 genes. Importantly, 746 genes with DET were not found by the gene-level analysis. We also identified novel exons derived from transposable elements (TEs). In the analysis of transcripts from hepatitis B virus (HBV), HBx-human TE fusions were found to be overexpressed in the HCCs. Furthermore, fusion gene detection showed novel recurrent fusion events. These results suggest that long-reads sequencing technologies allow us to analyze full-length transcripts, and show the importance of splicing variants in carcinogenesis.

cancer biology↗

bioRxiv2021

Aberrant integration of Hepatitis B virus DNA promotes major restructuring of human hepatocellular carcinoma genome architecture

Most cancers are characterized by the somatic acquisition of genomic rearrangements during tumour evolution that eventually drive the oncogenesis. There are different mutational mechanisms causing structural variation, some of which are specific to particular cancer types. Here, using multiplatform sequencing technologies, we identify and characterize a remarkable mutational mechanism in human hepatocellular carcinoma caused by Hepatitis B virus, by which DNA molecules from the virus are inserted into the tumour genome causing dramatic changes in its configuration, including non-homologous chromosomal fusions and megabase-size telomeric deletions. This aberrant mutational process, present in at least 8% of all HCC tumours, is active early during liver cancer evolution and can provide the driver rearrangements that a cancer clone requires to survive and grow.

cancer biology↗

bioRxiv2020

Intravenous edaravone plus therapeutic hypothermia offers limited neuroprotection in the hypoxic-ischaemic newborn piglet

Therapeutic hypothermia is a standard therapy for neonatal hypoxic-ischaemic encephalopathy. One potential additional therapy is the free radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one). To compare the neuroprotective effects of edaravone plus therapeutic hypothermia with those of therapeutic hypothermia alone after a hypoxic-ischaemic insult in the newborn piglet, anaesthetized piglets were subjected to 40 min of hypoxia (3-5% inspired oxygen) and cerebral ischaemia was assessed by cerebral blood volume. Body temperature was maintained at 38.5 {degrees}C in the normothermia group (NT, n = 8) and at 34 {degrees}C (24 h after the insult) in the therapeutic hypothermia (TH, n = 7) and therapeutic hypothermia plus edaravone (3 mg intravenous every 12 h for 3 days after the insult; TH+EV, n = 6) groups under mechanical ventilation. Five days after the insult, the mean (standard deviation) neurological scores were 10.9 (5.7) in the NT group, 17.0 (0.4) in the TH group (p = 0.025 vs. NT) and 15.0 (3.9) in the TH+EV group. The histopathological score of the TH+EV group showed no significant improvement compared with that of the other groups. In conclusion, edaravone plus therapeutic hypothermia had no additive neuroprotective effects after hypoxia-ischaemia in neurological and histopathological assessments.

neuroscience↗

bioRxiv2018

Genome-wide association meta-analysis identifies novel GP2 gene risk variants for pancreatic cancer in the Japanese population

The etiology of pancreatic cancer remains largely unknown. Here, we report the results of a meta-analysis of three genome-wide association studies (GWASs) comprising 2,039 pancreatic cancer cases and 32,592 controls, the largest sample size in the Japanese population. We identified 3 (13q12.2, 13q22.1, and 16p12.3) genome-wide significant loci (P<5.0x10-8) and 4 suggestive loci (P<1.0x10-6) for pancreatic cancer. Of these risk loci, 16p12.3 is novel; the lead SNP maps to rs78193826 (odds ratio (OR)=1.46, 95% CI=1.29-1.66, P=4.28x10-9), an Asian-specific, nonsynonymous glycoprotein 2 (GP2) gene variant predicted to be highly deleterious. Additionally, the gene-based GWAS identified a novel gene, KRT8, which is linked to exocrine pancreatic and liver diseases. The identified GP2 gene variants were pleiotropic for multiple traits, including type 2 diabetes, hemoglobin A1c (HbA1c) levels, and pancreatic cancer. Mendelian randomization analyses corroborated causality between HbA1c and pancreatic cancer. These findings suggest that GP2 gene variants are associated with pancreatic cancer susceptibility in the Japanese population, prompting further functional characterization of this locus.

genetics↗

bioRxiv2018

Characterization of oral microbiota in marmosets: feasibility of using the marmoset as a human oral disease model

As the worlds population is aging, there is an increasing demand for research regarding aging and aging-related disorders, to achieve better understanding of aging. Ideally, such research would be performed with human subjects. However, due to ethical considerations, animals such as rodents and monkeys are used as alternatives. Among these alternative models, non-human primates are preferred because they share common traits with humans. The small South American common marmoset (Callithrix jacchus) may offer a number of advantages over other non-human primates in terms of its relatively small size, short life span, and identical dental anatomy, compared with humans. The purpose of this study was to clarify the viability of using the marmoset as a human oral disease model.\n\nWe collected saliva samples from eight common marmosets and eight human subjects. Prokaryotic DNA was extracted from the saliva samples, and 16S bacterial rRNA gene sequencing was performed on each of the samples. Our results indicated that the types of oral microbiomes detected among human and marmoset samples were nearly identical. In contrast, the oral microbiomes of our human and marmoset subjects were distinctly different from those of rat and dogs, which are popular animal models. The oral microbiomes of marmosets showed greater diversity than those of humans. With respect to individual variation, marmosets exhibited less variation in their oral flora, compared with humans. This difference in variation might be attributed to the fact that marmoset subjects were kept in a controlled environment with identical lifestyles.\n\nThe characteristics of its oral microbiota, combined with other technical advantages, suggest that the marmoset may provide the best animal model thus far for the study of oral health. This study characterized the oral microbes of the marmoset, thereby providing information to support future application of the marmoset as a model for age-related oral disease.

microbiology↗