Biology subjects

Tada, M.

Publications and source records attributed to Tada, M..

9 recordsLinked to original sources

bioRxiv2026

Genetically interacting mutations and mechanical stress affect the stochasticity of developmental eye defects in yap1 mutants

Congenital abnormalities of eye formation show remarkably variable penetrance with phenotypes even varying between left and right eyes. Here we explore this phenomenon through analysis of the mechanistic basis of low penetrance retinal coloboma in zebrafish yap1nl13/nl13 mutants and identification of factors that modify the probability of this phenotype. We find that the low penetrance stochastically occurring coloboma in yap1nl13/nl13 mutants is due to rupture in the ventral retina at the point of apposition of the lips of the closing choroid fissure and that provision of wild-type Yap in the retinal pigment epithelium suppressed this phenotype. Decreasing actomyosin contractility increased the penetrance of coloboma whereas increasing myosin phosphorylation rescued the phenotype suggesting that altered mechanical properties of the RPE sensitize the eye to stochastic failure of choroid fissure closure. Genetic interaction screening revealed enhanced and synthetic eye phenotypes in yap1nl13/nl13mutants upon abrogation of function of genes encoding extracellular matrix and other genes implicated in eye formation. Our data reveal that the variable penetrance of congenital eye abnormalities can be due to genetic and environmental factors impacting the stochastic variability inherent in the developmental processes underlying eye morphogenesis.

developmental biology↗

bioRxiv2026

Vicious circle of amyloid and leptomeningeal macrophages evokes vascular dysfunction in CAA

The subarachnoid space contains leptomeningeal arteries and resident immune cells known as subarachnoid macrophages (SAMs). In Alzheimers disease (AD) and related cerebral amyloid angiopathy, amyloid-{beta} (A{beta}) frequently accumulates around the leptomeningeal arteries. Nevertheless, the local immune responses and their functional consequences remain poorly understood. Using longitudinal intravital imaging in a mouse model of AD, we tracked A{beta} deposition and identified a distinct SAM population that migrates to and phagocytoses these arterial A{beta} deposits. SAM recruitment correlated with vascular remodeling, including smooth muscle loss, aneurysm formation, and reduced cerebral perfusion. Transcriptomic profiling revealed a distinct SAM population in AD with upregulated CD39 expression. Pharmacological inhibition of CD39 attenuated arterial A{beta} deposition, identifying SAMs as a potential therapeutic target in AD.

neuroscience↗

bioRxiv2024

Machine-learning convergent melanocytic morphology despite noisy archival slides

Melanocytic atypia, ranging from benign to malignant, often leads to diagnostic discordance, complicating its prediction by machine learning models. To overcome this, we paired H&E-stained histology images with contiguous or serial sections immunohistochemically (IHC) stained for melanocytic cells via antibodies for MelanA, MelPro, or SOX10. We developed a deep-learning pipeline to identify melanocytic atypia by digitizing a real-world archival dataset of 122 paired whole slide images from 61 confirmed melanoma in situ (MIS) cases at two institutions. Only 37.7% of the cases contained tissue pairs that matched well enough for deep learning. Nonetheless, the MelanA+MelPro models achieved an average area under the receiver-operating characteristic (AUROC) of 0.948 and an average area under the precision-recall curve (AUPRC) of 0.611, while the SOX10 models had an average of 0.867 AUROC and 0.433 AUPRC. Despite learning from biologically different IHC stains, the convolutional neural network (CNN) models independently exhibited an intuitive convergent rationale by explainable AI saliency calculations. Different antibodies, with nuclear versus cytoplasmic staining, provided complementary yet consistent information, which the CNNs integrated effectively. The resulting multi-antibody virtual stains identified morphologic cytologic and small-scale architectural features directly from H&E-stained histology images, which can assist pathologists in assessing cutaneous MIS.

pathology↗

bioRxiv2024

Key role of P230 in the hinge region on the IgG architecture and function

Immunoglobulin G (IgG) is a molecule that plays an important role in biological defense; IgG molecules have been applied as drugs due to their high specificity for antigens and their ability to activate immunity via effector molecules on immune cells. On the other hand, the flexibility of the hinge region makes it difficult to apply conventional structural biology approaches due to its dynamic conformational changes, and the mechanism of action of the molecule as a whole has not been elucidated. Here, we introduced a deletion amino acid mutation in the hinge region to elucidate the role of the hinge region and its effect on the structure and function of the IgG molecule. Deletion of Pro230 resulted in the formation of a half-molecular in which the interaction between heavy chains was lost. We elucidated the mechanism of half-IgG formation by structural analysis using nuclear magnetic resonance (NMR) measurements and by disulfide quantification using peptide mapping using LC-MS/MS. For this purpose, a new NMR stable isotope labeling method was introduced. Finally, cell assay revealed that the IgG half-molecules have specific Fc{gamma}RI-mediated activity. This report provides new insights into the higher-order structure formation of IgG molecules and is expected to contribute to the elucidation of the molecular basis of the Fc{gamma} receptor-mediated activation mechanism of the immune system.

biophysics↗

bioRxiv2024

An analysis of contractile and protrusive cell behaviours at the superficial surface of the zebrafish neural plate

The motive forces underlying convergence and internalisation of the teleost neural plate remain unknown. To help understand this crucial morphogenetic movement we have analysed collective and individual cell behaviours at the superficial surface of the neural plate. Convergence to the midline does not rely on mediolateral cell intercalation, it is characterised by oscillatory contractile behaviours, a punctate distribution of Cdh2 and medially polarised actin-rich protrusions at the surface of the neural plate. Additionally, we characterise and discuss the intimate relationship and dynamic cell surfaces between the motile neural plate and the stationary overlying non-neural enveloping layer.

developmental biology↗

bioRxiv2023

A multi-tiered mechanical mechanism shapes the early neural plate

The formation of complex tissues during embryonic development requires an intricate spatiotemporal coordination of local mechanical processes regulating global tissue morphogenesis. Here, we uncover a novel mechanism that mechanically regulates the shape of the anterior neural plate (ANP), a vital forebrain precursor, during zebrafish gastrulation. Combining in vivo and in silico approaches we reveal that the ANP is shaped by global tissue flows regulated by distinct force generating processes. We show that mesendoderm migration and E-cadherin-dependent differential tissue interactions control distinct flow regimes in the neuroectoderm. Initial opposing flows lead to progressive tissue folding and neuroectoderm internalisation which in turn provide forces driving ANP tissue reshaping. We find that convergent extension is dispensable for internalisation but required for ANP tissue extension. Our results highlight how spatiotemporal regulation and coupling of different mechanical processes between tissues in the embryo controls the first folding event in the developing brain.

developmental biology↗

bioRxiv2021

Age-related demethylation of the TDP-43 autoregulatory region in the human motor cortex

In amyotrophic lateral sclerosis (ALS), TAR DNA-binding protein 43 (TDP-43), which is encoded by TARDBP, forms aggregates in the motor cortex. This aggregate formation may be triggered by an increase in the TDP-43 level with aging. However, the amount of TDP-43 is autoregulated by alternative splicing of the TARDBP 3UTR, and how this autoregulation is affected by aging remains to be elucidated. We found that DNA demethylation in the autoregulatory region in the TARDBP 3'UTR reduced alternative splicing and increased TARDBP mRNA expression. Furthermore, in the human motor cortex, we found that this region was demethylated with aging, resulting in increased expression of TARDBP mRNA. The acceleration of DNA demethylation in the motor cortex was associated with the age of ALS onset. In summary, the dysregulation of TDP-43 autoregulation by age-related DNA demethylation in the motor cortex may explain the contribution of aging and motor system selectivity in ALS.

molecular biology↗

bioRxiv2020

Alzheimer's Aβ assembly binds sodium pump and blocks endothelial NOS activity via ROS-PKC pathway

Amyloid {beta}-protein (A{beta}) may contribute to worsening of Alzheimers disease (AD) through vascular dysfunction, but the actual molecular mechanisms remain controversial. Using ex-vivo blood vessels and primary endothelial cells derived from human brain microvessels, we revealed that patient-derived A{beta} assemblies, termed amylospheroids (ASPD), exist on the microvascular surface in patient brains and inhibit vasorelaxation through binding to the 3 subunit of sodium, potassium-ATPase (NAK3) on endothelial cells. Interestingly, NAK3 also serves as the toxic target of ASPD in neurons. ASPD elicit neurodegeneration through calcium overload, while ASPD suppress vasorelaxation by inhibiting nitric oxide (NO) production. ASPD-NAK3 interaction on cerebrovascular endothelial cells disturbs the NO release by inactivating endothelial NO synthase through mitochondrial reactive oxygen species and protein kinase C. The findings suggest that ASPD may dually contribute to neuronal and vascular pathologies through binding to NAK3. Thus, blocking the ASPD-NAK3 interaction may be a useful target for AD therapy.

biochemistry↗

bioRxiv2018

Src-transformed cells hijack mitosis to extrude from the epithelium

At the initial stage of carcinogenesis single mutated cells appear within an epithelium. Mammalian in vitro experiments show that potentially cancerous cells undergo live apical extrusion from normal monolayers. However, the mechanism underlying this process in vivo remains poorly understood. Mosaic expression of the oncogene vSrc in a simple epithelium of the early zebrafish embryo results in apical extrusion of transformed cells. Here we find that during extrusion components of the cytokinetic ring are recruited to adherens junctions of transformed cells, stimulating formation of a misoriented pseudo cytokinetic ring. During extrusion, the ring constricts and separates the basal from the apical part of the cell releasing both from the epithelium. This process requires cell cycle progression and occurs immediately after vSrc-transformed cell enters mitosis. To achieve extrusion, vSrc coordinates cell cycle progression, junctional integrity, cell survival and apicobasal polarity. Without vSrc, modulating these cellular processes reconstitutes vSrc-like extrusion, confirming their sufficiency for this process.

cell biology↗