Biology subjects

Kuchimaru, T.

Publications and source records attributed to Kuchimaru, T..

4 recordsLinked to original sources

bioRxiv2026

Inflammasome activation drives gasdermin-independent plasma membrane rupture by clustering ninjurin-1 in macrophages

Inflammasome assembly rapidly triggers caspase-1 activation to initiate pyroptosis, an inflammatory cell death characterized by the release of cytosolic contents, including interleukin (IL)-1{beta}/. Here, we report that inflammasome activation drives necrotic cell death independent of gasdermin D (GSDMD) and GSDME, which are essential executors of pyroptosis by forming a pore on the plasma membrane and increasing membrane permeability. NLRP3 inflammasome activation induced necrotic cell death, coupled with IL-1{beta}/ release in Gsdmd-/-Gsdme-/- macrophages. Mechanistically, the oligomerization of ninjurin-1 (NINJ1) was caused by inflammasome activation even in the absence of GSDMD and GSDME. Concordantly, glycine, an inhibitor of NINJ1, blocked plasma membrane permeabilization triggered by inflammasome activation in Gsdmd-/-Gsdme-/- macrophages, but not in WT macrophages. The dimerizer-mediated ASC oligomerization promoted NINJ1-mNeonGreen cluster formation in the absence of GSDMD and GSDME. Moreover, NINJ1 deficiency prevented membrane permeabilization initiated by ASC oligomerization in Gsdmd-/-Gsdme-/- immortalized bone marrow-derived macrophages (iBMDM). Blocking of phosphatidylserine (PtdSer) exposure, a feature of inflammasome-driven necrotic cell death, by Xkr8 deficiency inhibited plasma membrane permeabilization in Gsdmd-/-Gsdme-/- iBMDM. These results suggest that inflammasome-triggered activation of caspase-1 itself drives inflammatory necrotic cell death independent of gasdermins.

cell biology↗

bioRxiv2026

The REFLEX system enables in vivo identification of perivascular angiogenic macrophages in the heart

Direct identification of physically interacting cells in vivo remains challenging because conventional interactome analyses infer signaling partners from transcriptomes and cannot reveal which cells are in direct contact. In pressure-overload induced cardiac remodeling, VEGF-A plays a central role in the maintenance of vascular integrity and cardiac function. However, the cell type which produces VEGF-A and how the VEGF-A peptide is delivered to vascular endothelial cells remains unclear. Here, we developed a genetically encoded platform that combines REFLEX mice with HUNTERuni-seq, enabling unbiased detection and transcriptional profiling of the cells that physically interact with vascular endothelial cells. The REFLEX and HUNTERuni-seq approach identified subpopulations of Vegfa positive macrophages which we named perivascular angiogenic macrophages (PVAMs). Although the amount of VEGF-A in PVAMs is small, loss of VEGF-A in PVAMs impaired angiogenesis and systolic function during pressure overload. We additionally show that direct contact between PVAMs and endothelial cells is critical for the delivery of VEGF-A to endothelial cells. Conventional interactome analysis predicted that cardiomyocytes as dominant sources of VEGF-A in the heart. However, cardiomyocyte Vegfa deletion had no effect on capillary density nor systolic function in a model of heart failure. These results suggest that VEGF-A signaling does not rely on free diffusion through the interstitium and that cellular proximity and physical contact between PVAMs and endothelial cells are the key determinants of effective signal delivery. Together, these findings establish REFLEX and HUNTERuni-seq as a versatile platform for uncovering biologically critical cell-to-cell interactions and provide new insight into intercellular communication in pathological tissue contexts.

cell biology↗

bioRxiv2026

Cell-autonomous thermogenesis of macrophage alters its antibacterial function

Dynamic temperature gradients exist across the bodies of endothermic animals, from the core to peripheral organ, resulting in the physiological cold environment in superficial regions. Consequently, macrophages distributed throughout the body must be able to adapt not only to thermoneutral conditions but also to colder environments. In fact, it is known that environmental temperature influences macrophage immune responses. However, the thermo-responsive mechanisms of macrophage have been largely unexplored. Here we show that macrophage themselves maintains intracellular temperature under physiological cold condition by increasing proton leak index (defined as mitochondrial proton leak per spare respiratory capacity). We further identified a contribution of ADP/ATP carrier (AAC) to this increase in proton leak index. This cell-autonomous thermogenesis pathway, which does not depend on neural or hormonal inputs, highlights the potential for local and organ-specific temperature regulation. Moreover, cold stress reduced mitochondrial membrane potential, which in turn suppressed the expression of the antimicrobial peptide Resistin-like molecule alpha (RETNLA) and diminished antibacterial properties. Together, these findings suggest that macrophages generate heat whereas compromising antibacterial properties, thereby increasing susceptibility to bacterial infection in physiological cold environment. This adaptation mechanism may underscore the important role of temperature homeostasis in non-adipocyte cells.

physiology↗

bioRxiv2025

A bright synthetic near-infrared luciferin enhances the capabilities of deep-tissue bioluminescence imaging using firefly luciferases

Synthetic bioluminescence reactions exhibiting near-infrared (NIR)-shifted spectra have been explored to improve deep-tissue imaging through the design of firefly luciferin analogues. Although the NIR bioluminescence reactions improve the tissue penetration of bioluminescence signals from deep tissues, their photon output is markedly lower compared to the natural reaction with D-luciferin and firefly luciferase (Fluc), often by an order of magnitude or more. Consequently, in most instances, the sensitivity of NIR bioluminescence imaging (NIR-BLI) has not yet substantially surpassed that of BLI with the natural firefly reaction. Here, we present a synthetic firefly luciferin, named AkaSuke, that generates intense NIR bioluminescence ({lambda}max = 680 nm) in reaction with Fluc, greatly improving the detection sensitivity beyond that of the D-luciferin/Fluc reaction for targeting deep tissue. AkaSuke enables sensitive visualizations of ectopic hematogenesis through entire tissues of mice over time following transplantation of bone marrow stem cells labeled with Fluc. We additionally identify a Japanese firefly luciferase, DkumLuc1, that displays higher catalytic activities for bioluminescence emission of AkaSuke compared to typical Fluc, resulting in detection sensitivity comparable to that of AkaLumine/Akaluc reaction, one of the most sensitive bioluminescence systems for deep tissue imaging. We further propose the potential of the AkaSuke/DkumLuc1 reaction as an orthogonal pair with the AkaLumine/Akaluc for sensitive dual-target tracking in mice. Overall results suggest that AkaSuke enhances the capabilities of deep-tissue bioluminescence imaging using Fluc and its variant, and could serve as an emerging benchmark for the molecular design of NIR luciferin analogues.

cancer biology↗