Biology subjects

Takao, M.

Publications and source records attributed to Takao, M..

7 recordsLinked to original sources

bioRxiv2025

Aggregation of HAPLN2, a component of the perinodal extracellular matrix, is a hallmark of physiological brain aging in mice

Protein aggregation is a hallmark of neurodegenerative diseases and is also observed in the brains of elderly individuals without such conditions, suggesting that aging drives the accumulation of protein aggregates. However, the comprehensive understanding of age-dependent protein aggregates involved in brain aging remains unclear. Here, we investigated proteins that become sarkosyl-insoluble with age and identified hyaluronan and proteoglycan link protein 2 (HAPLN2), a hyaluronic acid-binding protein of the extracellular matrix at the nodes of Ranvier, as an age-dependent aggregating protein in mouse brains. Elevated hyaluronic acid levels and impaired microglial function reduced the clearance of HAPLN2, leading to its accumulation. HAPLN2 oligomers induced microglial inflammatory responses both in vitro and in vivo. Furthermore, age-associated HAPLN2 aggregation was also observed in the human cerebellum. These findings suggest that HAPLN2 aggregation results from age-related decline in brain homeostasis and may exacerbate the brain environment by activating microglia. This study provides new insights into the mechanisms underlying cerebellar aging and highlights the role of HAPLN2 in age-associated changes in the brain. Author SummaryTo identify age-dependent protein aggregates unrelated to disease, we analyzed the sarkosyl-insoluble proteome of young and aged mouse brains. We discovered that hyaluronan and proteoglycan link protein 2 (HAPLN2), a hyaluronic acid-binding protein existing in the nodal extracellular matrix, accumulated with age. Age-dependently accumulated HAPLN2 formed large protein aggregates that cannot be solubilized by the anionic detergent sarkosyl or by hyaluronidase digestion. In addition, HAPLN2 formed irregularly shaped puncta that were mislocalized from the nodes of Ranvier in the cerebellar white matter of not only aged mice but also aged human brains. Oligomers of full-length HAPLN2 specifically induced microglial activation in vitro and in vivo. Our findings suggest that the accumulation of HAPLN2 aggregates is a new hallmark of brain aging and a possible factor contributing to brain inflammation.

biochemistry↗

bioRxiv2024

Dnmt1 determines bone length by regulating energy metabolism of growth plate chondrocytes

Chondrocytes differentiated from mesenchymal stem cells play a role in determining skeletal patterns by ossification. However, the mechanism by which maintenance DNA methylation in chondrocytes regulates differentiation and skeletal formation is unclear. In the Musculoskeletal Knowledge Portal, Dnmt1 was significantly associated with "Height". Long bones in the limbs of Dnmt1-deficient (Dnmt1{Delta}Prx1) mice are significantly shortened due to decreased chondrocyte proliferation and accelerated differentiation. Integrated analysis of RNA-Seq and MBD-Seq revealed that in Dnmt1{Delta}Prx1 chondrocytes reduced DNA methylation resulted in increased expression of genes related to energy metabolism and to ossification. Metabolomic analyses confirmed that levels of nearly all energy metabolites were increased in Dnmt1{Delta}Prx1 chondrocytes. These results indicate that Dnmt1-mediated maintenance DNA methylation governs chondrocyte differentiation by regulating energy metabolism through both gene expression and modulation of metabolite supplies. Taken together, this study suggests that appropriate DNA methylation status in chondrocytes can orchestrate growth plate mineralization and subsequently determine bone length.

developmental biology↗

bioRxiv2023

A single-cell atlas of transcribed cis-regulatory elements in the human genome

Transcribed cis-regulatory elements (tCREs), such as promoters and enhancers, are fundamental to modulate gene expression and define cell identity. The detailed mapping of tCREs at single-cell resolution is essential for understanding the regulatory mechanisms that govern cellular functions. Prior tCRE catalogs, limited by bulk analysis, have often overlooked cellular heterogeneity. We have constructed a tCRE atlas using single-cell 5-RNA-seq, capturing over 340,000 single-cells from 23 human tissues and annotating more than 175,000 tCREs, substantially enhancing the scope and granularity of existing cis-regulatory element annotations in the human genome. This atlas unveils patterns of gene regulation, revealing connections between broadly expressed promoters and cell type-specific distal tCREs. Assessing trait heritability at single-cell resolution with a novel tCRE module-based approach, we uncovered the nuanced trait-gene regulatory relationships across a continuum of cell populations, offering insights beyond traditional gene-level and bulk-sample analyses. Our study bridges the gap between gene regulation and trait heritability, underscoring the potential of single-cell analysis to elucidate the genetic foundations of complex traits. These insights set the stage for future research to investigate the impact of genetic variations on diseases at the individual level, advancing the understanding of cellular and molecular basis of trait heritability.

genomics↗

bioRxiv2023

Identical tau filaments in subacute sclerosing panencephalitis and chronic traumatic encephalopathy

Subacute sclerosing panencephalitis (SSPE) occurs in some individuals after measles infection, following a symptom-free period of several years. It resembles chronic traumatic encephalopathy (CTE), which happens after repetitive head impacts or exposure to blast waves, following a symptom-free period. As in CTE, when present, the neurofibrillary changes of SSPE are concentrated in superficial cortical layers. Here we used electron cryo-microscopy of tau filaments from two cases of SSPE to show that the tau folds of SSPE and CTE are identical. Two types of filaments were each made of two identical protofilaments with an extra density in the {beta}-helix region. Like in CTE, the vast majority of tau filaments were Type I, with a minority of Type II filaments. These findings suggest that the CTE tau fold can be caused by different environmental insults, which may be linked by inflammatory changes.

neuroscience↗

bioRxiv2022

New SNCA mutation and structures of α-synuclein filaments from juvenile-onset synucleinopathy

A 21-nucleotide duplication in one allele of SNCA was identified in a previously described disease with abundant -synuclein inclusions that we now call juvenile-onset synucleinopathy (JOS). Both wild-type -synuclein and its insertion mutant containing seven additional residues (MAAAEKT) after residue 22 were present in sarkosyl-insoluble material that was extracted from frontal cortex of the individual with JOS and examined by electron cryo-microscopy. The structures of JOS filaments, comprising either a single protofilament, or a pair of protofilaments, revealed a new -synuclein fold that differs from the folds of Lewy body diseases and multiple system atrophy (MSA). The JOS fold consists of a compact core, the sequence of which (residues 36-100 of wild-type -synuclein) is unaffected by the mutation, and two disconnected density islands (A and B) of mixed sequences. There is a non-proteinaceous cofactor bound between the core and island A. The JOS fold resembles the common substructure of MSA type I and type II dimeric filaments, with its core segment approximating the C-terminal body of MSA protofilaments B and its islands mimicking the N-terminal arm of MSA protofilaments A. The partial similarity of JOS and MSA folds extends to the locations of their cofactor-binding sites. Our findings provide insight into a likely mechanism of JOS fibrillation in which mutant -synuclein of 147 amino acids forms a nucleus with the JOS fold, around which wild-type and mutant proteins assemble during elongation.

neuroscience↗

bioRxiv2022

Distinct chaperonopathy in skeletal muscle associated with the dominant variant in DNAJB4

DnaJ homolog, subfamily B, member 4, a member of the heat shock protein 40 chaperones encoded by DNAJB4, is highly expressed in myofibers. We identified a heterozygous c.270 T>A (p.F90L) variant in DNAJB4 in a family with a dominantly inherited distal myopathy, in which affected members have specific features on muscle pathology represented by the presence of cytoplasmic inclusions and the accumulation of desmin, p62, HSP70 and DNAJB4 predominantly in type 1 fibers. Both Dnajb4- F90L knock-in and knockout mice developed muscle weakness and recapitulated the patient muscle pathology in the soleus muscle, where DNAJB4 has the highest expression. These data indicate that the identified variant is causative resulting in defective chaperone function and selective muscle degeneration in specific muscle fibers. This study demonstrates the importance of DNAJB4 in skeletal muscle proteostasis by identifying the associated chaperonopathy.

neuroscience↗

bioRxiv2021

Age-dependent formation of TMEM106B amyloid filaments in human brain

Many age-dependent neurodegenerative diseases, like Alzheimers and Parkinsons, are characterised by abundant inclusions of amyloid filaments. Filamentous inclusions of the proteins tau, amyloid-{beta} (A{beta}), -synuclein and TDP-43 are the most common. Here, we used electron cryo-microscopy (cryo-EM) structure determination to show that residues 120-254 of the lysosomal type II transmembrane protein 106B (TMEM106B) also form amyloid filaments in the human brain. We solved cryo-EM structures of TMEM106B filaments from the brains of 22 individuals with neurodegenerative conditions, including sporadic and inherited tauopathies, A{beta}-amyloidoses, synucleinopathies and TDP-43opathies, as well as from the brains of two neurologically normal individuals. We observed three different TMEM106B folds, with no clear relationship between folds and diseases. The presence of TMEM106B filaments correlated with that of a 29 kDa sarkosyl-insoluble fragment of the protein on Western blots. The presence of TMEM106B filaments in the brains of older, but not younger, neurologically normal individuals indicates that they form in an age-dependent manner.

neuroscience↗