Biology subjects

Tsukamoto, S.

Publications and source records attributed to Tsukamoto, S..

8 recordsLinked to original sources

bioRxiv2026

Molecular Force Gates Regulate Mechanical Transmission Across the Nuclear Envelope

The LINC (linker of nucleoskeleton and cytoskeleton) complex is a central mechanotransductive apparatus that physically couples cytoskeletal forces to the nuclear interior, thereby regulating nuclear architecture, chromatin organization, and downstream signaling. Using atomistic molecular dynamics simulations, we identify and characterize force gates within the LINC complex, structural interactions that maintain mechanical connectivity under load. By introducing targeted mutations into the KASH peptide and SUN protein, we provide computational evidence that a key disulfide bond (SUN2 Cys563 to KASH2 Cys6862) and specific residues within the KASH {beta} strand interaction motif (KASH6875, KASH6877) act as distinct mechanical elements during force transmission across the SUN and KASH interface. Leveraging this framework, we show that the disulfide bond and the {beta} sheet network contribute unequally: removing the disulfide reduces both sustained and peak force transmission approximately twofold, whereas disrupting the {beta} sheet network leaves peak force largely intact while altering interfacial coupling and the duration over which load is borne. Localized molecular changes therefore reshape mechanical coupling to the nucleus through distinct routes rather than through a single graded loss of force. Such altered LINC mechanics may be relevant to laminopathies, including Hutchinson Gilford Progeria Syndrome (HGPS), in which defective nuclear lamina compromises force transmission; however, implications for specific diseases remain speculative and require experimental validation. By resolving how distinct molecular contacts contribute to force transmission in space and sequence, this work establishes a framework for dissecting mechanical coupling at protein interfaces under load. These findings provide a foundation for future studies aimed at experimentally testing how individual interface interactions govern nuclear force transmission, a prerequisite for therapeutically targeting LINC mechanics. More broadly, the force gate framework may guide strategies to modulate interfaces that bear mechanical loads in other mechanically regulated proteins. Together, these findings establish a computational framework for investigating force transmission at mechanically loaded protein interfaces and provide experimentally testable predictions for future studies.

cell biology↗

bioRxiv2026

HDAC3 inhibition stabilizes the IL-37 receptor module to enhance anti-inflammatory signaling in cystic fibrosis airway epithelium

Airway inflammation in cystic fibrosis (CF) persists despite advances in CFTR modulator therapy. IL-37b suppresses innate immune signaling through a receptor complex containing IL-18R and wild-type SIGIRR (WT-SIGIRR; IL-1R8), but this pathway is compromised in CF airway epithelial cells by the dominant-negative exon 8-skipped SIGIRR isoform ({Delta}8-SIGIRR). Here, a natural-product screen identified short-chain fatty acids as preferential enhancers of WT-SIGIRR. Pan-HDAC inhibition with panobinostat increased WT-SIGIRR, reduced {Delta}8-SIGIRR, and restored IL-37b-dependent suppression of the TLR3 ligand poly(I:C)-induced IL-8 production. Isoform-selective inhibitor screening and siRNA knockdown identified HDAC3 as a regulator of the IL-37 receptor module. Low concentrations of RGFP966 and HDAC3 silencing increased WT-SIGIRR and IL-18R protein abundance without inducing their mRNA levels. HDAC3 inhibition delayed proteasome-dependent WT-SIGIRR turnover and stabilized IL-18R, thereby enhancing IL-37b-mediated anti-inflammatory signaling in CF airway epithelial cells.

cell biology↗

bioRxiv2025

Dietary soy shapes murine microbiota to consolidate the mucosal IgA response through T follicular helper cells

The commensal microbiota plays a crucial role in shaping mucosal immunity, particularly in the induction of T follicular helper (Tfh) cells and IgA production. Here, we demonstrate that dietary soy elicits a robust Tfh cell and IgA response in Peyers patches of weaning mice. Soy feeding promotes the expansion of two principal commensal bacterial species, Limosilactobacillus reuteri and Muribaculum intestinale. Mechanistically, L. reuteri provides cognate antigens for Tfh cell activation, while M. intestinale functions as an adjuvant by promoting IL-1{beta} production from myeloid cells. The resulting IgA exhibits polyreactivity and enhances protection against Salmonella infection. These findings highlight the specific interplay among dietary components, intestinal microbiota, and mucosal immunity, thereby establishing a diet-microbe-immune axis that shapes host defense in early life. This axis represents a promising therapeutic target for developing novel strategies to enhance resistance to enteric pathogens. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=170 HEIGHT=200 SRC="FIGDIR/small/669459v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@1ae8277org.highwire.dtl.DTLVardef@1f787ceorg.highwire.dtl.DTLVardef@1f51fd6org.highwire.dtl.DTLVardef@1fd3439_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIDietary soy promotes T follicular helper (Tfh) cell and IgA responses in the Peyers patches of weaning mice. C_LIO_LISoy enhances the colonization of two key commensals, Limosilactobacillus reuteri and Muribaculum intestinale, in the small intestine. C_LIO_LIThese two bacteria synergize to drive mucosal immunity: L. reuteri provides cognate antigens, while M. intestinale provides an adjuvant signal by promoting IL-1{beta} production from myeloid cells. C_LIO_LISoy-induced IgA is polyreactive and protects against Salmonella infection. C_LI

immunology↗

bioRxiv2024

Expanding the HP1a-binding consensus and molecular grammar for heterochromatin assembly

The recruitment of Heterochromatin Protein 1 (HP1) partners is essential for heterochromatin assembly and function, yet our knowledge regarding their organization in heterochromatin remains limited. Here we show that interactors engage the Drosophila HP1 (HP1a) dimer through a degenerate and expanded form of the previously identified PxVxL motif, which we now term HP1a Access Codes (HACs). These HACs reside in disordered regions, possess high conservation among Drosophila homologs, and contain alternating hydrophobic residues nested in a cluster of positively charged amino acids. These findings and molecular dynamics simulations identify key electrostatic interactions that modulate HP1a-binding strength and provide a dramatically improved HP1a-binding consensus motif that can reveal protein partners and the molecular grammar involved in heterochromatin assembly. We propose HP1a acts as a scaffold for other heterochromatin components containing HAC motifs, which in turn may regulate the function and higher order structure of the heterochromatin compartment.

molecular biology↗

bioRxiv2024

TRPC6 is a mechanosensitive channel essential for ultrasound neuromodulation in mammalian brain

Ultrasound neuromodulation has become an innovative technology that enables non-invasive intervention in mammalian brain circuits with high spatiotemporal precision. Despite the expanding utility of ultrasound neuromodulation in the neuroscience research field and clinical applications, the molecular and cellular mechanisms by which ultrasound impacts neural activity in the brain are still largely unknown. Here, we report that transient receptor potential canonical 6 (TRPC6), a mechanosensitive non-selective cation channel, is essential for ultrasound neuromodulation of mammalian neurons in vitro and in vivo. We first demonstrated that ultrasound irradiation elicited rapid and robust Ca2+ transients mediated via extracellular Ca2+ influx in cultured mouse cortical and hippocampal neurons. Ultrasound-induced neuronal responses were massively diminished by blocking either the generation of action potential or synaptic transmission. Importantly, both pharmacological inhibition and genetic deficiency of TRPC6 almost completely abolished neuronal responses to ultrasound. Furthermore, we found that intracerebroventricular administration of a TRPC6 blocker significantly attenuated the population of neuronal firings in the cerebral cortex evoked by transcranial ultrasound irradiation in mice. Our findings indicate that TRPC6 is an indispensable molecule of ultrasound neuromodulation in the intact mammalian brains, providing fundamental understanding of biophysical molecular mechanisms of ultrasound neuromodulation as well as insight into its future feasibility in neuroscience and translational researches in humans.

neuroscience↗

bioRxiv2021

Shared and unique properties of place cells in anterior cingulate cortex and hippocampus

Hippocampal sharp-wave ripples (SWRs) and the associated replay of neuronal sequences are well-established as the primary physiological substrates for memory consolidation. While the local transformations they induce within the hippocampus are well-characterized, their impact on the downstream cortical representations remains unknown. Here, we identify a distinct functional class of neurons in the anterior cingulate cortex "spatial context cells" that emerge through the multi-day integration of discrete hippocampal inputs. Using closed-loop disruption of SWRs and longitudinal calcium imaging, we demonstrate that formation of this global spatial framework depends on SWRs during offline periods. Whereas standard cortical place maps remain intact following SWR disruption, the emergence of spatial context cells is selectively abolished. These cells preferentially express c-Fos, identifying them as constituents of the cortical memory engram, and exhibit broad receptive fields that develop through an experience-dependent process of field convergence. Collectively, these findings establish SWR-mediated replay as a computational bridge transforming high-resolution, fragmented hippocampal spatial codes into generalized, stable cortical schemas. This work reveals a bifurcated consolidation process, identifying SWR-dependent synaptic remodeling as a fundamental mechanism for the ontogeny of remote memory.

neuroscience↗

bioRxiv2021

Metastatic Single Tumor Cells Evade NK Cell-mediated Killing by Thrombin-mediated Loss of the Activating Ligand CD155/PVR/Necl-5

Natural killer (NK) cells lyse invading tumor cells to limit metastatic growth in the lung, but how some cancers evade this host protective mechanism to establish a growing lesion is not known. Here we have combined ultra-sensitive bioluminescence whole body imaging with intravital two-photon microscopy involving genetically-encoded biosensors to examine this question. NK cells eliminated disseminated tumor cells from the lung within 24 hrs of arrival, but not thereafter. Intravital dynamic imaging revealed that a disseminated tumor cell in a pulmonary capillary interacts with an NK cell every 2 hrs on average. In the first 4 hrs after tumor cell arrival, 50% of such encounters lead to tumor cell death but after 24 hrs of arrival, nearly 100% of the interactions result in the survival of the tumor cell. This evasion of NK cell surveillance is mediated by thrombin-dependent loss of cell surface CD155/PVR/Necl-5, a ligand for the NK cell activating receptor DNAM-1. This loss prevents the NK cell signaling needed for effective killing of tumor targets. By quantitatively visualizing the evasion of NK cell surveillance, we have uncovered a molecular mechanism for cancer evasion and provided an explanation for the anti-metastatic effect of anticoagulants. SUMMARYIntravital functional two-photon microscopy reveals that metastatic tumor cells lodged in pulmonary capillaries acquire resistance to patrolling NK cells. Protease-mediated loss of the activating ligand CD155/PVR/Necl-5 on tumor cells prevents NK cells from ERK activation and tumor cell killing.

immunology↗

bioRxiv2019

An evolutionarily conserved mechanism for production of secondary meristems in land plants

A variety of plants in diverse taxa can reproduce asexually via vegetative propagation, in which clonal propagules with new meristem(s) are generated directly from vegetative organs. A basal land plant, Marchantia polymorpha, develops clonal propagules, gemmae, in a specialized receptacle, gemma cup. Here we report an R2R3-MYB transcription factor, designated GEMMA CUP-ASSOCIATED MYB 1 (GCAM1), which is an essential regulator of gemma cup development in M. polymorpha. Although gemma cups are a characteristic gametophyte organ for vegetative reproduction in a taxonomically restricted group of liverwort species, phylogenetic and interspecific complementation analyses supported the orthologous relationship of GCAM1 to regulatory factors for axillary meristem formation, e.g. Arabidopsis RAXs and tomato Blind, in angiosperm sporophytes. The present findings in M. polymorpha suggest an ancient acquisition of a regulatory mechanism for production of secondary meristems, and the use of the mechanism for diverse developmental programs during land plant evolution.

plant biology↗