Biology subjects

Masuda, M.

Publications and source records attributed to Masuda, M..

9 recordsLinked to original sources

bioRxiv2026

Chronic stress disrupts the network among stress granules, P-bodies, and motor proteins

Stress granules (SGs) are dynamic RNA granules that rapidly form in response to various stresses concurrent with mRNA translation shutdown, contributing to cellular adaptation and disease pathogenesis. While SG assembly and disassembly under acute stress have been extensively characterized, how SGs behave under chronic stress remains poorly understood. We previously reported that chronic stress preconditioning inhibits the earliest steps of SG assembly via translation-dependent mechanisms. In contrast, the regulation of SG maturation under chronic stress has not yet been investigated. Here, we show that chronic stress decreases SG size by disrupting the MYH9-dependent myosin crosstalk with core SG nucleator G3BP1. This defect leads to impaired SG and processing body (PB) docking as well, limiting the biogenesis of early SGs. Furthermore, chronic stress reduces expression of the SG nucleator UBAP2L, required for SG-PB docking, thus exacerbating these deficiences. In summary, chronic stress disrupts the myosin-SG-PB network and inhibits SG maturation in a translation-independent manner. SummaryChronic stress disrupts the MYH9 network with G3BP1, which inhibits stress granule (SG) assembly. It also decreases UBAP2L levels, which inhibits SG and processing body docking. Disrupted MYH9 network further inhibits this docking, thus blocking maturation of SGs.

cell biology↗

bioRxiv2025

Aberrant Hippo-YAP/TEAD signaling drives malignant transcriptional reprogramming in external auditory canal squamous cell carcinoma

PurposeExternal auditory canal squamous cell carcinoma (EACSCC) is an extremely rare malignancy. The molecular characteristics and evidence-based therapeutic strategies of EACSCC still remain to be elucidated. Experimental DesignComprehensive analyses of RNA sequencing (RNA-seq) and ChIP sequencing (ChIP-seq) utilizing YAP and H3K27Ac antibodies were performed in primary EACSCC and noncancerous ear skin samples. Functional experiments were performed in EACSCC-derived cells and Head and Neck Squamous Cell Carcinoma (HNSCC) cells in vitro and in vivo. Immunohistochemical staining of primary EACSCC tissues as well as survival analysis were conducted. ResultsRNA-seq indicated hyperactivation of YAP/TEAD-mediated transcriptional programs in EACSCC. H3K27Ac ChIP-seq suggested gained accessibility for transcription factor (TF) binding sites for TEAD, AP-1 and PITX TFs in EACSCC, and presence of EACSCC-specific super enhancers (SEs). YAP-bound SEs were involved in oncogenic transcription, including EGFR signaling. Small molecule TEAD inhibitor (smTEADi) VT104 showed significant suppression of proliferation and clonogenicity in EACSCC cells. Importantly, smTEADi not only inhibited YAP-TEAD interaction but also induced YAP-PITX2 binding, suggesting that PITX2 could represent an alternative partner TF of YAP under TEAD-inhibited conditions. Knockdown of PITX2 inhibited cell growth and migration of EACSCC and HNSCC cells, whereas overexpression of PITX2 induced expression of cell cycle, stemness, and EMT genes, as well as YAP/TAZ-TEAD target genes, and promoted tumor growth in vivo. Nuclear YAP and PITX2 expression were significantly correlated with poor prognosis of EACSCC patients. ConclusionsThis study highlighted the hyperactivation of the YAP-TEAD/PITX2 transcriptional program and its potential as a therapeutic target in EACSCC. Translational RelevanceExternal auditory canal squamous cell carcinoma (EACSCC) is an extremely rare malignancy related to chronic tissue damage and inflammation. Due to its rarity, the molecular characteristics of EACSCC are poorly understood, and evidence-based therapeutic strategies are not fully developed. Here, we provide evidence of hyperactivation of YAP/TEAD-driven transcriptional programs in EACSCC, utilizing comprehensive analyses of RNA-seq and YAP/H3K27Ac ChIP-seq in clinical tissue samples, as well as in vitro and in vivo experiments. In addition, our data suggest that the PITX2 transcription factor (TF) could represent an alternative partner TF of YAP under TEAD-inhibited conditions, which may rescue oncogenic transcription of TEAD. Importantly, YAP and PITX2 are co-expressed in EACSCC and predict poor prognosis of EACSCC patients. Our results provide a rationale for YAP-hyperactivation in EACSCC and contribute to a better understanding of this malignancy and the development of new therapeutic strategies.

cancer biology↗

bioRxiv2024

Chronic stress antagonizes formation of Stress Granules

Chronic stress mediates cellular changes that can contribute to human disease. However, fluctuations in RNA metabolism caused by chronic stress have been largely neglected in the field. Stress granules (SGs) are cytoplasmic ribonucleoprotein condensates formed in response to stress-induced inhibition of mRNA translation and polysome disassembly. Despite the broad interest in SG assembly and disassembly in response to acute stress, SG assembly in response to chronic stress has not been extensively investigated. In this study, we show that cells pre-conditioned with low dose chronic (24-hour exposure) stresses such as oxidative stress, endoplasmic reticulum stress, mitochondrial stress, and starvation, fail to assemble SGs in response to acute stress. While translation is drastically decreased by acute stress in pre-conditioned cells, polysome profiling analysis reveals the partial preservation of polysomes resistant to puromycin-induced disassembly. We showed that chronic stress slows down the rate of mRNA translation at the elongation phase and triggers phosphorylation of translation elongation factor eEF2. Polysome profiling followed by RNase treatment confirmed that chronic stress induces ribosome stalling. Chronic stress-induced ribosome stalling is distinct from ribosome collisions that are known to trigger a specific stress response pathway. In summary, chronic stress triggers ribosome stalling, which blocks polysome disassembly and SG formation by subsequent acute stress. Significant statementsStress granules (SGs) are dynamic cytoplasmic biocondensates assembled in response to stress-induced inhibition of mRNA translation and polysome disassembly. SGs have been proposed to contribute to the survival of cells exposed to toxic conditions. Although the mechanisms of SG assembly and disassembly in the acute stress response are well understood, the role of SGs in modulating the response to chronic stress is unclear. Here, we show that human cells pre-conditioned with chronic stress fail to assemble SGs in response to acute stress despite inhibition of mRNA translation. Mechanistically, chronic stress induces ribosome stalling, which prevents polysome disassembly and subsequent SG formation. This finding suggests that chronically stressed or diseased human cells may have a dysfunctional SG response that could inhibit cell survival and promote disease.

cell biology↗

bioRxiv2024

Label-free imaging of cellular organization in living mammalian cells via external apodization phase-contrast microscopy

Developing techniques to visualize intracellular structures, which influence the spatiotemporal functionality of biomolecules, is essential for elucidating mechanisms governing cellular behavior. In this study, we demonstrate that label-free external apodization phase-contrast (ExAPC) microscopy serves as a valuable tool for the simultaneous observation of various intracellular structures with high spatiotemporal resolution, while successfully mitigating halo artifacts. Additionally, through quantitative analysis of images obtained by combining ExAPC microscopy with fluorescence microscopy, we identified distinct heterogeneities in biomolecular condensates, lipid droplets, and mitochondria. Our findings highlight the potential of ExAPC microscopy to provide detailed insights into alterations in intracellular structures associated with diverse cellular processes, corroborating the existing knowledge and potentially contributing to the discovery of novel cellular mechanisms.

cell biology↗

bioRxiv2023

Activation of the IKK2-NFκB pathway in VSMCs inhibits calcified vascular stiffness in CKD by reducing the secretion of calcifying extracellular vesicles.

IKK2-NF{kappa}B pathway mediated-inflammation in vascular smooth muscle cells (VSMCs) has been proposed to be an etiologic factor in medial calcification and stiffness. However, the role of the IKK2-NF{kappa}B pathway in medial calcification remains to be elucidated. In this study, we found that CKD induces inflammatory pathways through the local activation of the IKK2-NF{kappa}B pathway in VMSCs associated with calcified vascular stiffness. Despite reducing the expression of inflammatory mediators, complete inhibition of the IKK2-NF{kappa}B pathway in vitro and in vivo unexpectedly exacerbated vascular mineralization and stiffness. In contrast, activation of NF{kappa}B by SMC-specific I{kappa}B deficiency attenuated calcified vascular stiffness in CKD. Inhibition of the IKK2-NF{kappa}B pathway induced apoptosis of VSMCs by reducing anti-apoptotic gene expression, whereas activation of NF{kappa}B reduced CKD-dependent vascular cell death. In addition, increased calcifying extracellular vesicles through the inhibition of the IKK2-NF{kappa}B pathway induced mineralization of VSMCs, which was significantly reduced by blocking cell death. This study reveals that activation of the IKK2-NF{kappa}B pathway in VSMCs plays a protective role in CKD-dependent calcified vascular stiffness by reducing the release of apoptotic calcifying extracellular vesicles.

physiology↗

bioRxiv2022

T cell-specific P2RX7 favors lung parenchymal CD4+ T cell accumulation in response to severe lung infections

CD4+ T cells are key components of the immune response during lung infections and can mediate protection against tuberculosis (TB) or influenza. However, CD4+ T cells can also promote lung pathology during these infections, making it unclear how these cells control such discrepant effects. Using mouse models of hypervirulent TB and influenza, we observed that exaggerated accumulation of parenchymal CD4+ T cells promotes lung damage. Low numbers of lung CD4+ T cells, in contrast, are sufficient to protect against hypervirulent TB. In both situations, lung CD4+ T cell accumulation is mediated by CD4+ T cell-specific expression of the extracellular ATP (eATP) receptor P2RX7. P2RX7 upregulation in lung CD4+ T cells promotes expression of the chemokine receptor CXCR3 and favors in situ proliferation. Our findings suggest that direct sensing of lung eATP by CD4+ T cells is critical to induce tissue CD4+ T cell accumulation and pathology during lung infections. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=168 SRC="FIGDIR/small/508603v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@a4cdaborg.highwire.dtl.DTLVardef@1ba95e1org.highwire.dtl.DTLVardef@c60984org.highwire.dtl.DTLVardef@19ac0af_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2021

All-trans retinoic acid induces GADD34 gene expression via transcriptional regulation by Six1-TLE3 and post-transcriptional regulation by p38-TTP in skeletal muscle

All-trans retinoic acid (ATRA) increases the sensitivity to unfolded protein response (UPR) in differentiating leukemic blasts. The downstream transcriptional factors of PERK, a major arm of UPR, regulates muscle differentiation. However, the role of growth arrest and DNA damage-inducible protein 34 (GADD34), one of the downstream factors of PERK, and the effects of ATRA on GADD34 expression in muscle remain unclear. In this study, we identified ATRA increased the GADD34 expression independent of the PERK signal in the gastrocnemius muscle of mice. ATRA up-regulated GADD34 expression through the transcriptional activation of it via inhibiting the interaction of homeobox Six1 and transcription co-repressor TLE3 with the MEF3-binding site on the GADD34 gene promoter in myoblasts. ATRA also inhibited the interaction of TTP, which induces mRNA degradation, with AU-rich element on GADD34 mRNA via p38 MAPK, resulting in the instability of GADD34 mRNA. Overexpressed GADD34 in myoblasts changes the type of myosin heavy chain in myotubes. These results suggest ATRA increases GADD34 expression via transcriptional and post-transcriptional regulation in myoblasts, which changes muscle fiber type in myotubes.

biochemistry↗

bioRxiv2021

Copy-out-paste-in transposition of a Tn6283-like integrative element assists interspecies antimicrobial resistance gene transfer from Vibrio alfacsensis

The exchange of antimicrobial resistance (AMR) genes between aquaculture and terrestrial microbial populations has emerged as a serious public health concern. However, the nature of the mobile genetic elements in marine bacteria is poorly documented. To gain insight into the genetic mechanisms underlying AMR gene transfer from marine bacteria, we mated a multidrug-resistant Vibrio alfacsensis strain with an Escherichia coli strain, and then determined the complete genome sequences of the donor and the transconjugant strains. Sequence analysis revealed a conjugative multidrug resistance plasmid in the donor strain, which was integrated into the chromosome of the recipient. The plasmid backbone in the transconjugant chromosome was flanked by two copies of a 7.1 kb unclassifiable integrative element harboring a {beta}-lactamase gene. The 7.1 kb element and the previously reported element Tn6283 share four coding sequences, two of which encode the catalytic R-H-R-Y motif of tyrosine recombinases. Polymerase chain reaction and sequencing experiments revealed that these elements generate a circular copy of one specific strand without leaving an empty site on the donor molecule, in contrast to the movement of integron gene cassettes or ICE/IMEs discovered to date. These elements are termed SEs (strand-biased circularizing integrative elements): SE-6945 (the 7.1 kb element) and SE-6283 (Tn6283). The copy number and location of SE-6945 in the chromosome affected the antibiotic resistance levels of the transconjugants. SEs were identified in the genomes of other Vibrio species. Overall, these results suggest that SEs are involved in the spread of AMR genes among marine bacteria.

microbiology↗

bioRxiv2020

Disentangling the biological information encoded in disordered mitochondrial morphology through its rapid elicitation by iCMM

Mitochondrial morphology is dynamically changed in conjunction with spatiotemporal functionality. Although considerable efforts have been made to understand why abnormal mitochondrial morphology occurs in various diseases, the biological significance of mitochondrial morphology in states of health and disease remains to be elucidated owing to technical limitations. In the present study, we developed a novel method, termed inducible Counter Mitochondrial Morphology (iCMM), to purposely manipulate mitochondrial morphological patterns on a minutes timescale, using a chemically inducible dimerization system. Using iCMM, we showed that mitochondrial morphological changes rapidly lead to the characteristic reconstitution of various biological information, which is difficult to investigate by conventional genetic engineering. The manipulation of mitochondrial morphology using iCMM can improve our understanding of the interplay between mitochondrial morphology and cellular functions.Competing Interest StatementThe authors have declared no competing interest.View Full Text

synthetic biology↗