To realize the continuous monitoring of insulin, the development of a regenerable engineered antibody is expected, whose binding constant is modulated by the mild in situ stimulation for future in vivo application. In this study, we aimed to develop pH-responsive anti-insulin antibodies based on a clinically established analytical antibody, the HUI-018 anti-insulin antibody. Its high-resolution co-crystal structure with human insulin (PDB ID: 6Z7W) provides a uniquely precise blueprint for molecular engineering by preparing engineered HUI-018 single-chain variable fragment (scFv). Among the engineered variants, the N93H/E101K mutant exhibited the biggest pH-responsiveness, showing a 5.2-folds increased dissociation rate at pH 6.0 while maintaining binding affinity and specificity comparable to wild-type (WT) at pH 7.4. Repeated cycles of insulin binding at pH 7.4 and regeneration at pH 6.0 demonstrated that the N93H/E101K mutant achieved substantially higher regeneration and rebinding efficiencies than WT. These results demonstrate that engineered pH-responsive antibody enables efficient binding site regeneration through mild pH change. To our knowledge, this is the first report of an anti-insulin antibody capable of binding site regeneration at pH 6.0, representing an important step toward antibody-based continuous insulin monitoring and continuous sensing of protein biomarkers.

Antibody delivery across the blood-brain barrier (BBB) remains challenging. We combined phage display with next-generation sequencing (NGS)-guided clone sequence-diverse selection to identify transferrin receptor 1 (TfR1)-binding VHH antibodies. Following alpacas immunization with human and rat TfR1, representative clones from distinct phylogenetic groups were screened for human/mouse cross-reactivity. Three clones (A1, Y11, and Z1) were reformatted as human Fc-mutant fusion proteins and characterized by ELISA, flow cytometry, and fluorescence imaging. All three clones recognized human and mouse TfR1, with ELISA EC50 >100 nM. After intravenous administration in mice, clone Y11 showed sustained brain-associated fluorescence up to 48 h, whereas A1 showed an initially high signal that progressively declined. Fluorescent microscopy revealed preferential localization of Y11 to NeuN-positive neuronal regions, whereas A1 to lectin-positive vascular structures, indicating distinct brain localization profiles among the isolated clones. These findings identify cross-reactive TfR1-targeting VHHs with distinct brain-localization profiles and potential utility as platforms for compartment-selective CNS drug delivery.

Ultraviolet (UV) radiation is a major environmental factor responsible for photocarcinogenesis and photoaging. Although these conditions have traditionally been regarded as distinct consequences of chronic UV exposure, accumulating evidence suggests that they share common molecular mechanisms mediated by macrophage migration inhibitory factor (MIF) family cytokines. MIF and its homolog D-dopachrome tautomerase (D-DT, also known as MIF-2) have emerged as important regulators of UV-induced skin damage. MIF family cytokines promote photocarcinogenesis by enhancing inflammatory responses and suppressing apoptosis of UV-damaged keratinocytes. They also contribute to photoaging by regulating matrix metalloproteinase expression, collagen degradation, and extracellular matrix remodeling. Together, these findings indicate that MIF family cytokines coordinate inflammation and tissue remodeling underlying both photocarcinogenesis and photoaging, highlighting them as promising therapeutic targets for preventing chronic UV-induced skin damage.

GATA2 is a transcription factor that is essential for vascular and lymphatic development. GATA2 deficiency causes lymphatic malformations and lymphedema. Delayed lymphatic recanalization after popliteal lymph node removal in Gata2 heterozygous (Gata2+/-) mice is associated with collagen accumulation in the surrounding tissue. In this study, we investigated whether extracellular matrix (ECM) alterations contribute to lymphatic recanalization by analyzing subcutaneous tissue from Gata2+/- and Gata2 and Gata3 double heterozygous (Gata2+/-::Gata3+/-) mice. RNA-seq analysis revealed changes in ECM-related and adhesion-associated genes in both genotypes. Histological analyses demonstrated collagen accumulation and disorganized collagen bundles in Gata2+/-::Gata3+/- mice. Immunostaining further revealed reduced elastin fibers and decreased numbers of fibroblasts in subcutaneous tissues of Gata2+/- and Gata2+/-::Gata3+/- mice. These findings suggest that abnormalities in ECM organization, including altered collagen and elastin structures and reduced fibroblast populations, may underlie collagen accumulation and impaired lymphatic recanalization. Notably, Gata2+/-::Gata3+/- mice exhibited a patchwork-like dermal phenotype reflecting features of both single mutants, possibly owing to mosaic transcriptional regulation within the GATA gene network. The microenvironmental ECM structure plays an important role in lymphatic recanalization following lymphatic injury.

Snake venoms contain enzymes whose biochemical activities cannot be inferred reliably from sequence or proteomic detection alone. Snake venom phosphodiesterase (svPDE), an extracellular ENPP-family glycoprotein, is generally regarded as a 3'-to-5' exonuclease, although endonucleolytic activity was reported in early preparations. Whether this activity is intrinsic to a molecularly defined svPDE and how DNA structure influences cleavage remained unresolved. Here, nuclease activity in Protobothrops flavoviridis venom was tracked by sequential chromatography, and LC-MS/MS identified svPDE in active fractions. Comparable activity was detected in a commercial Crotalus atrox PDE I preparation. Purified, sequence- and structure-defined Naja atra svPDE converted covalently closed circular plasmid DNA to open-circular and then linear forms in a concentration-dependent manner; higher concentrations caused extensive degradation. Moreover, N. atra svPDE converted a plasmid containing a single nick at a defined position into linear DNA, and restriction mapping was consistent with complementary-strand cleavage at or near the nick. These results establish endonucleolytic activity as an intrinsic property of svPDE and suggest that its nuclease action may be influenced by structural features associated with DNA topology and strand discontinuities. Thus, svPDE may facilitate double-strand breakage at or near sites of single-strand discontinuity, expanding the biochemical repertoire of this conserved venom enzyme.

In eukaryotes, single-stranded DNA (ssDNA) generated during DNA replication, recombination, and repair is rapidly bound and protected by the major single-stranded DNA-binding protein replication protein A (RPA). RPA not only stabilizes ssDNA but also acts as a central platform that coordinates diverse DNA transactions. Exhaustion of RPA due to unregulated ssDNA production leads to replication fork breakage and replication catastrophe, underscoring its critical role in genome stability. However, the direct consequences of RPA limitation remain incompletely understood. Using Xenopus egg extracts, we show that excess ssDNA induces spontaneous priming, a reaction that is otherwise prevented in a physiological nuclear environment. We provide evidence that priming suppression is mediated by stoichiometric binding of RPA to ssDNA. Analysis of the ssDNA-binding proteome reveals that RPA promotes the association of ATR checkpoint factors, Polα-primase, and the RFWD3 ubiquitin ligase with ssDNA. In contrast, RPA depletion induces the recruitment of Rad51, Rad51 paralogs, and Fbh1, a DNA helicase that interacts with both RPA and Rad51 and promotes fork breakage under replication stress. Collectively, our findings suggest that RPA contributes to genome stability by protecting ssDNA from inappropriate DNA synthesis and unscheduled recruitment of recombination and fork-processing factors.

Transcription factors (TFs) are sequence-specific DNA-binding proteins that regulate gene-expression programs and cell fate. The ability of a defined combination of four TFs to reprogram differentiated cells into induced pluripotent stem cells illustrates the powerful role of TFs in determining cellular identity. However, TFs usually recognize short and degenerate DNA motifs of approximately 6-12 base pairs, generating thousands to millions of potential motif matches in mammalian genomes. In living cells, TFs occupy only a restricted subset of these sites, indicating that motif presence alone is insufficient for functional target selection. Several layers of regulation contribute to this selective occupancy, including DNA methylation, nucleosome organization, histone modifications, chromatin remodeling, TF oligomerization, TF availability and localization, and cofactors that regulate DNA-binding domains. This review outlines how DNA/chromatin features and TF-centered mechanisms contribute to target-site selection. The principal aim is to highlight DNA-binding domain-directed cofactor regulation as an underappreciated mechanism that modulates TF-DNA binding and may help explain selective genomic occupancy.

We identified and characterized a homocysteine S-methyltransferase (HMT) from the lactic acid bacterium Leuconostoc suionicum LT-38, representing the first characterization of an HMT from lactic acid bacteria. The enzyme exhibited a kcat/Km value of 15.7 mM-1 s-1 toward L-homocysteine. It showed optimal activity at 30 °C and pH 7.5 and remained stable over a broad range of temperatures (30-60 °C) and pH values (5-9). The enzyme accepted both L- and D-homocysteine as methyl acceptors but displayed markedly higher catalytic efficiency toward the L-form (~30-fold). In contrast, L- and D-cysteine were not utilized. Both S-methyl-L-methionine and S-methyl-D-methionine were consumed in reactions containing racemic S-methyl-DL-methionine, and S-adenosyl-L-methionine was also accepted, whereas betaine and related compounds were not utilized. Gel filtration analysis indicated a monomeric structure (~32 kDa). Phylogenetic analysis showed that Ls-HMT clustered with bacterial HMT homologs and was distinct from mammalian BHMT/BHMT2 proteins. Inductively coupled plasma-mass spectrometry revealed approximately one Zn atom per enzyme molecule, and the Zn-depleted apo enzyme showed no detectable activity. These findings support that Ls-HMT is a Zn-dependent HMT with relatively high activity and expand the functional diversity of microbial HMTs.

Muscle satellite cells (MuSCs) are muscle-resident stem cells that are responsible for myofiber regeneration. Although the importance of calcium ions (Ca 2+) in muscle physiology has been well established, the mechanism by which Ca 2+ mobilization governs MuSC function remains poorly understood. In this study, we aimed to systematically characterize Ca2+ dynamics in MuSCs and to define the mechanisms regulating these signals during muscle regeneration. By employing modified protocols for mouse MuSC isolation and Ca2+ measurement, we observed spontaneous Ca2+ fluctuations in MuSCs isolated from regenerating muscle after cardiotoxin-induced myofiber injury. Our detailed analysis using chemical Ca2+ indicators and a genetically encoded Ca2+ indicator revealed that the frequency and amplitude of Ca2+ fluctuations increased significantly during the activated and proliferative stages of MuSCs. This effect was more pronounced in MuSCs isolated from dystrophic and aged mice. Mechanistically, these Ca2+ fluctuations were at least partially mediated by mechanosensitive ion channels, including PIEZO1 and TRPM7, which promote MuSC migration. Collectively, our findings demonstrate that Ca2+ fluctuations through mechanosensitive ion channels act as a key regulator of MuSC activation during muscle regeneration and may provide new insights into the role of Ca2+ influx in muscle biology and the pathogenesis of muscle diseases.

The Japanese government adopted the 'Seventh Science, Technology, and Innovation Basic Plan' (the Seventh Basic Plan) on March 27, 2026. Covering the period from fiscal years 2026-2030, the Seventh Basic Plan was formulated by the Council for Science, Technology, and Innovation (CSTI) in response to a formal inquiry from the Prime Minister. The Seventh Basic Plan not only aims to reverse the decline in Japan's research capabilities but also presents a strategy to rebuild an environment where scientists can pursue ambitious ideas and translate discoveries into innovations. At its core is a commitment to 'Revitalizing Science' as the foundation for future innovation.

Brain neurons rely predominantly on glucose as an energy source and express glucose transporter 3 (GLUT3) as their principal glucose transporter. Unlike GLUT4, which undergoes insulin-stimulated membrane translocation in peripheral tissues, GLUT3 mediates largely constitutive and relatively insulin-independent glucose uptake in neurons. Although GLUT3 is essential for neuronal functions, its regulatory mechanisms are not fully understood. Microtubule affinity-regulating kinase 4 (MARK4), a member of the AMP-activated protein kinase-related kinase family, has been implicated in Alzheimer's disease and metabolic regulation in peripheral tissues. Here, we show that MARK4 knockdown in primary neurons reduces GLUT3 surface expression and consequently decreases glucose uptake. While MARK4 knockdown did not alter the intracellular distribution of GLUT3 or mitochondria, it reduced mitochondrial abundance. We further found that MARK4 activity is negatively regulated by the insulin/IGF-1-GSK3β signaling axis in primary neurons. Despite these acute metabolic effects in cultured neurons, Mark4-null mice exhibited no overt morphological abnormalities in the brain. Together, these findings identify MARK4 as a regulator of neuronal glucose uptake by modulating GLUT3 surface expression and suggest that MARK4 functions as a modulatory rather than essential component of neuronal metabolic homeostasis.

Obesity and alcoholism are major global health burdens driven in part by maladaptive ingestive behaviors. Accordingly, functional foods that curb overeating and excessive alcohol consumption may help prevent these disorders. Ingestion of simple sugars or alcohol increases plasma fibroblast growth factor 21 (FGF21), which activates oxytocin (OXT) neurons in the paraventricular nucleus of the hypothalamus (PVH) and suppresses the specific appetite for sugar and alcohol. D-Allulose and D-tagatose are generally recognized as safe rare sugars and serve as potent inducers of FGF21. Oral administration of these sugars elevates plasma FGF21 to levels sufficient to reduce preference for simple sugars and alcohol without altering palatability. In mice, they also prevent the development of diet-induced obesity and alcohol dependence. Mechanistically, these effects involve activating transcription factor 4 (ATF4)-dependent induction of FGF21 and activation of the FGF21-PVHOXT negative feedback system. Thus, rare sugars such as D-allulose and D-tagatose may improve ingestive behaviors and help prevent obesity and alcoholism.

Supersulfides, a class of catenated sulfur-containing biomolecules, are increasingly recognized as key regulators of redox signaling, mitochondrial function, and inflammatory responses. Recent evidence suggests that lysosomes, central organelles for intracellular degradation and nutrient sensing, are closely linked to supersulfide metabolism through lysosomal acidification, cysteine metabolism, and autophagy. Conversely, supersulfides modulate lysosomal activity and inflammatory responses. This review summarizes recent progress in supersulfide biology and lysosomal regulation and discusses evidence supporting functional interactions between these systems. We propose the lysosome-supersulfide axis as a new concept in cellular homeostasis and metabolic regulation.

Fucosylated haptoglobin (Fuc-Hp) has been recognized as a cancer-associated glycoform. We previously established a monoclonal antibody, 10-7G mAb, which detects both Fuc-Hp and its precursor prohaptoglobin (proHp). Recent studies have suggested that proHp itself may serve as a cancer-associated biomarker with clinical implications distinct from those of Fuc-Hp. Importantly, proHp is produced during inflammation and cancer progression and may exert biological activities different from mature haptoglobin. These observations highlight the need for a reagent that can specifically detect proHp. However, to date, no antibody strictly specific to proHp has been available. In this study, we generated a monoclonal antibody, 21-4F mAb, that specifically recognizes human proHp without cross-reactivity to mature Hp. Using 21-4F mAb, we developed a proHp-specific ELISA and integrated it with assays for several types of Hp, enabling independent quantification of three Hp-related isoforms. Serum analyses of healthy volunteers and patients with chronic pancreatitis or pancreatic cancer revealed distinct alterations among these isoforms, and their combined use provided the highest diagnostic performance. Taken together, 21-4F mAb offers a novel analytical tool for investigating the pathophysiological significance of proHp and may contribute to the development of refined biomarker panels for cancer diagnosis and disease monitoring.