Biology subjects

Matsuzaki, S.

Publications and source records attributed to Matsuzaki, S..

11 recordsLinked to original sources

bioRxiv2026

Amyloid precursor protein interacts with the mitochondrial phosphatase PGAM5 and regulates mitochondrial respiration

Amyloid Precursor Protein (APP) has been reported to partially localize to mitochondria, and mitochondrial dysfunction is a key feature of Alzheimers disease; however, the mechanisms linking APP to mitochondrial functions remain incompletely defined. In this study, we identified an interaction between APP and phosphoglycerate mutase family member 5 (PGAM5), a mitochondrial protein phosphatase. We confirmed their endogenous interaction in mouse brain tissue and determined that APP and PGAM5 are both present at mitochondria-ER contact sites (MERCS) and. Using in vitro binding assays, we demonstrate a direct interaction between the linker region of APP and a region of PGAM5 that includes the Kelch-like ECH-associated protein 1 (Keap-1) binding domain. PGAM5 is known to anchor a portion of Nuclear factor erythroid 2 p45-related factor 2 (Nrf2) through Keap1 at the outer mitochondrial membrane and regulates mitochondrial respiration and stress responses. We found that the Nrf2-regulated genes Hmox1 (Heme oxygenase-1) and Nqo1 (NADH:quinone oxidoreductase 1), which are involved in mitochondrial respiration, are downregulated in APP KO astrocytes. Accordingly, mitochondria isolated from the brains of APP knockout (KO) mice have impaired substrate-specific respiration and electron transport chain (ETC) function. Together, these findings suggest that APP supports mitochondrial respiration by binding to PGAM5 and modulating Keap1-Nrf2 signaling.

neuroscience↗

bioRxiv2025

Multimodal Analysis of Sepsis-induced Cardiomyopathy in a Baboon Model

Sepsis-induced cardiomyopathy (SIC) significantly contributes to sepsis-related morbidity and mortality, necessitating a deeper understanding of its mechanisms. This study used a post-hoc, multimodal approach--including single-nucleus RNA sequencing (snRNA-seq), echocardiography, mitochondrial function, and histopathology--to characterize SIC in a non-human primate model. Archived data and samples from six baboons challenged with 37.5 mg/kg of purified peptidoglycan were analyzed. Vital signs and echocardiography were monitored for 8 hours; the endpoint was survival at 168 hours or euthanasia for irreversible organ failure. Septic shock--defined by hypotension, tachycardia, and elevated lactate--was associated with poor outcomes. Echocardiography showed reduced intravascular volume, contraction, stroke volume, and cardiac index. SnRNA-seq revealed distinct transcriptomic profiles: non-survivors exhibited inflammation, mitochondrial dysfunction, and maladaptive remodeling; survivors showed activation of pathways supporting contraction, metabolism, and repair. Cell-type analysis highlighted metabolic dysfunction in cardiomyocytes, TNF/NF-{kappa}B-driven inflammation in endothelial cells, and stress responses in fibroblasts and pericytes. Mitochondrial analysis showed impaired electron transport and disrupted metabolism. Histopathology revealed inflammation and myofibrillar damage, more severe in non-survivors. This model recapitulates key SIC features and supports mechanistic and therapeutic discovery.

pathology↗

bioRxiv2025

PFKFB2 is Pivotal for Metabolic Flexibility and Differential Glucose Utilization

BackgroundThe hearts constant energy demands make metabolic flexibility critical to its function as nutrient availability varies. The enzyme phosphofructokinase-2/fructose 2,6-bisphosphatase (PFKFB2) contributes to this flexibility by acting as a positive or negative regulator of cardiac glycolysis. We have previously shown that PFKFB2 is degraded in the diabetic heart and that a cardiac-specific PFKFB2 knockout (cKO) impacts ancillary glucose pathways and mitochondrial substrate preference. Therefore, defining PFKFB2s role in mitochondrial metabolic flexibility is paramount to understanding both metabolic homeostasis and metabolic syndromes. Further, it is unknown how PFKFB2 loss impacts the hearts response to acute stress. Here we examined how cardiac mitochondrial flexibility and the post-translational modification O-GlcNAcylation are affected in cKO mice in response to fasting or pharmacologic stimulation. MethodscKO and litter-matched controls (CON) were sacrificed in the fed or fasted (12 hours) states, with or without a 20 minute stimulant stress of caffeine and epinephrine. Mitochondrial respiration, metabolomics, and changes to systemic glucose homeostasis were evaluated. ResultscKO mice had moderate impairment in mitochondrial metabolic flexibility, affecting downstream glucose oxidation, respiration, and CPT1 activity. O-GlcNAcylation, a product of ancillary glucose metabolism, was upregulated in cKO hearts in the fed state, but this was ameliorated in the fasted state. Furthermore, metabolic remodeling in response to PFKFB2 loss was sufficient to impact circulating glucose in fasted and stressed states. ConclusionsPFKFB2 is essential for fed-to-fasted changes in cardiac metabolism and plays an important regulatory role in protein O-GlcNAcylation. Its loss also affects systemic glucose homeostasis under stressed conditions. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/656235v1_ufig1.gif" ALT="Figure 1000"> View larger version (50K): org.highwire.dtl.DTLVardef@158c873org.highwire.dtl.DTLVardef@1d0312eorg.highwire.dtl.DTLVardef@14ce8deorg.highwire.dtl.DTLVardef@4c4883_HPS_FORMAT_FIGEXP M_FIG C_FIG Research PerspectiveThis study raises and answers three key questions: how PFKFB2 contributes to cardiac mitochondrial metabolic flexibility, how post-prandial status regulates O-GlcNAcylation in a PFKFB2-dependent manner, and how altered cardiac glucose use impacts systemic glucose homeostasis under stress. These findings highlight a novel role for nutrient state in regulating cardiac metabolism, and especially O-GlcNAcylation, with PFKFB2 loss. Future studies should investigate whether reducing O-GlcNAcylation through fasting is sufficient to ameliorate pathological changes observed in the absence of PFKFB2.

biochemistry↗

bioRxiv2024

Mechanistic studies of PFKFB2 reveals a novel inhibitor of its kinase activity

The 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB) family of proteins are bifunctional enzymes that are of clinical relevance because of their roles in regulating glycolysis in insulin sensitive tissues and cancer. Here, we sought to express recombinant PFKFB2 and develop a robust protocol to measure its kinase activity. These studies resulted in the unexpected finding that bacterially expressed PFKFB2 is phosphorylated in situ on Ser483 but is not a result of autophosphorylation. Recombinant PFKFB2 was used to develop an enzymatic assay to test a library of molecules selected by the Atomwise AtomNet(R) AI platform. This resulted in the identification of a new inhibitor, B2, that inhibits PFKFB2 (IC50 3.29 M) and PFKFB3 (IC50 11.89 M). A-498 cells, which express both PFKFB2 and PFKFB3, were treated with B2. Seahorse XFe analysis revealed B2 inhibited cellular glycolysis and glycolytic capacity. Targeted LC/MS analysis showed B2 decreased fructose-1,6-bisphosphate and downstream glycolytic intermediates but increased fructose-6-phosphate levels, which is consistent with an inhibitory effect on PFK-1 activity. The LC/MS metabolic profile of A-498 cells treated under identical conditions with the known PFKFB3 inhibitor, PFK158, was distinct from that induced by B2. These results thus demonstrate the identification and validation of a new PFKFB kinase inhibitor.

biochemistry↗

bioRxiv2024

Host-encoded DNA methyltransferases modify the epigenome and host tropism of invading phages

Restriction modification (RM) systems are ubiquitous bacterial defense systems; however, some phages evade RM system and adapt to their bacterial hosts. In such cases, phages are thought to stochastically acquire DNA methylation from host-encoded DNA methyltransferases (MTases), facilitating host adaptation. However, no studies have directly compared the methylomes of host bacteria and their infecting phages. Here, we demonstrate the epigenetic landscape of adapted phages with diverse infection histories, focusing on the broad host-range phage KHP30T as its adapts to three Helicobacter pylori strains. Using a multistage infection system, we observed that the adapted phages displayed significantly high titers against the last infected H. pylori strain, suggesting an attendant change in host tropism. Single-molecule real-time sequencing revealed that methylated motifs were predominantly shared between the adapted phages and their most recent host. Our findings enhance our understanding of epigenetic phage-host interactions, which have significant implications for microbial ecology.

microbiology↗

bioRxiv2023

Loss of cardiac PFKFB2 drives Metabolic, Functional, and Electrophysiological Remodeling in the Heart

BackgroundPhosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2) is a critical glycolytic regulator responsible for upregulation of glycolysis in response to insulin and adrenergic signaling. PFKFB2, the cardiac isoform of PFK-2, is degraded in the heart in the absence of insulin signaling, contributing to diabetes-induced cardiac metabolic inflexibility. However, previous studies have not examined how the loss of PFKFB2 affects global cardiac metabolism and function. MethodsTo address this, we have generated a mouse model with a cardiomyocyte-specific knockout of PFKFB2 (cKO). Using 9-month-old cKO and control (CON) mice, we characterized impacts of PFKFB2 on cardiac metabolism, function, and electrophysiology. ResultscKO mice have a shortened lifespan of 9 months. Metabolically, cKO mice are characterized by increased glycolytic enzyme abundance and pyruvate dehydrogenase (PDH) activity, as well as decreased mitochondrial abundance and beta oxidation, suggesting a shift toward glucose metabolism. This was supported by a decrease in the ratio of palmitoyl carnitine to pyruvate-dependent mitochondrial respiration in cKO relative to CON animals. Metabolomic, proteomic, and western blot data support the activation of ancillary glucose metabolism, including pentose phosphate and hexosamine biosynthesis pathways. Physiologically, cKO animals exhibited impaired systolic function and left ventricular (LV) dilation, represented by reduced fractional shortening and increased LV internal diameter, respectively. This was accompanied by electrophysiological alterations including increased QT interval and other metrics of delayed ventricular conduction. ConclusionsLoss of PFKFB2 results in metabolic remodeling marked by cardiac ancillary pathway activation. This could delineate an underpinning of pathologic changes to mechanical and electrical function in the heart. Clinical PerspectiveO_ST_ABSWhat is New?C_ST_ABSO_LIWe have generated a novel cardiomyocyte-specific knockout model of PFKFB2, the cardiac isoform of the primary glycolytic regulator Phosphofructokinase-2 (cKO). C_LIO_LIThe cKO model demonstrates that loss of cardiac PFKFB2 drives metabolic reprogramming and shunting of glucose metabolites to ancillary metabolic pathways. C_LIO_LIThe loss of cardiac PFKFB2 promotes electrophysiological and functional remodeling in the cKO heart. C_LI What are the Clinical Implications?O_LIPFKFB2 is degraded in the absence of insulin signaling, making its loss particularly relevant to diabetes and the pathophysiology of diabetic cardiomyopathy. C_LIO_LIChanges which we observe in the cKO model are consistent with those often observed in diabetes and heart failure of other etiologies. C_LIO_LIDefining PFKFB2 loss as a driver of cardiac pathogenesis identifies it as a target for future investigation and potential therapeutic intervention. C_LI

physiology↗

bioRxiv2022

SUMO2 Protects Against Tau-induced Synaptic and Cognitive Dysfunction

Abnormal intracellular accumulation of Tau aggregates is a hallmark of Alzheimers disease (AD) and other Tauopathies, such as Frontotemporal dementia (FTD), which can be caused by mutations of Tau. Mutated and pathological Tau can undergo a range of post-translational modifications (PTMs) that might trigger or modulate disease pathology. Recent studies indicate that modification of wild type Tau by Small ubiquitin-like modifier SUMO isoform 1 (SUMO1) controls Tau hyperphosphorylation and aggregation, suggesting that SUMOylation acts as a central regulator of Taus biochemical properties. Besides SUMO1, Tau is modified by SUMO2/3, however the consequences of this modification have not been investigated. Here, using viral approaches on primary hippocampal neurons, transgenic mice expressing mutant Tau and SUMO2, and iPSC-derived neurons from FTD patients, we evaluated whether SUMO2/3 conjugation modifies the neurodegenerative disease pathology associated with the aggregation-prone mutant Tau P301L, P301S, and R406W variants. We found that mutant forms of Tau are targets of SUMO2/3, and SUMO2/3 conjugation is neuroprotective. Importantly, expression of mutant Tau is accompanied by a significant reduction of SUMO2/3 conjugation levels, and restoring levels of SUMO2 reduces mutant Tau aggregation and phosphorylation in all model systems Furthermore, overexpression of SUMO2 restores levels of pre- and post-synaptic markers, associated with a complete rescue of the LTP and memory deficits in transgenic mice expressing mutant Tau. These findings bring to light the potential therapeutic implication of manipulating SUMO conjugation to detoxify Tau through PTM-based approaches.

neuroscience↗

bioRxiv2022

p66Shc is an apoptotic rheostat whose targeted ROS inhibition improves MI outcomes

p66Shc is an oxidoreductase that responds to cell stress by translocating to mitochondria, where p66Shc produces pro-apoptotic reactive oxygen species (ROS). This study identifies ROS-active p66Shc as a monomer that produces superoxide anion independent of metal ions, inhibits cytochrome c peroxidase, and is regulated by environmental condition-induced structural changes. p66Shc anti-apoptotic functions, including: cytochrome c reduction, increased electron transport chain activity, and caspase cascade inhibition were also discovered. This study also demonstrates that p66Shc is a stress-dependent rheostat of apoptosis, regulated by p66Shc-mortalin complexes. These complexes decrease pro-apoptotic ROS production, without blocking p66Shc-mediated cytochrome c reduction. However, stress disrupts p66Shc-mortalin interactions, promoting apoptosis. Tipping p66Shcs apoptotic balance toward anti-apoptotic functions by genetic knockdown or p66Shc-selective ROS inhibition decreased pro-apoptotic effects and improved outcomes in zebrafish myocardial infarction models, representing a potential new myocardial infarction treatment with promising results.

biochemistry↗

bioRxiv2021

Mutations in a β-group of solute carrier gene are responsible for egg and eye coloration of the brown egg 4 (b-4) mutant in the silkworm, Bombyx mori

The brown egg 4 (b-4) is a recessive mutant in the silkworm (Bombyx mori), whose egg and adult compound eyes exhibit a reddish-brown color instead of normal purple and black, respectively. By double digest restriction-site associated DNA sequencing (ddRAD-seq) analysis, we narrowed down a region linked to the b-4 phenotype to approximately 1.1 Mb that contains 69 predicted gene models. RNA-seq analysis in a b-4 strain indicated that one of the candidate genes had a different transcription start site, which generates a short open reading frame. We also found that exon skipping was induced in the same gene due to an insertion of a transposable element in other two b-4 mutant strains. This gene encoded a putative amino acid transporter that belongs to the {beta}-group of solute carrier (SLC) family and is orthologous to Drosophila eye color mutant gene, mahogany (mah). Accordingly, we named this gene Bmmah. We performed CRISPR/Cas9-mediated gene knockout targeting Bmmah. Several adult moths in generation 0 (G0) had totally or partially reddish-brown compound eyes. We also established three Bmmah knockout strains, all of which exhibit reddish-brown eggs and adult compound eyes. Furthermore, eggs from complementation crosses between the b-4 mutants and the Bmmah knockout mutants also exhibited reddish-brown color, which was similar to the b-4 mutant eggs, indicating that Bmmah is responsible for the b-4 phenotypes. HighlightO_LIResponsible region for the brown egg 4 (b-4) mutation was narrowed down by double digest restriction-site associated DNA sequencing (ddRAD-seq). C_LIO_LIThe gene structure was disrupted in one of the candidate genes, Bombyx mori mahogany (Bmmah), in the b-4 mutant strains. C_LIO_LICRISPR/Cas9-mediated gene knockout and complementation test confirmed that the Bmmah is responsible for the b-4 phenotypes. C_LIO_LIThe Bmmah encoded a putative amino acid transporter that belongs to the {beta}-group of solute carrier family. C_LIO_LIThe Bmmah gene is essential for normal colorization of eggs, compound eyes, and ganglions. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=76 SRC="FIGDIR/small/436376v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@10d1d56org.highwire.dtl.DTLVardef@12df5org.highwire.dtl.DTLVardef@1703701org.highwire.dtl.DTLVardef@2b5bcf_HPS_FORMAT_FIGEXP M_FIG C_FIG

genetics↗

bioRxiv2020

Diabetes induced decreases in PKA signaling in cardiomyocytes: the role of insulin

The cAMP-dependent protein kinase (PKA) signaling pathway is the primary means by which the heart regulates moment-to-moment changes in contractility and metabolism. We have previously found that PKA signaling is dysfunctional in the diabetic heart, yet the underlying mechanisms are not fully understood. The objective of this study was to determine if decreased insulin signaling contributes to a dysfunctional PKA response. To do so, we isolated adult cardiomyocytes (ACMs) from wild type and Akita type 1 diabetic mice. ACMs were cultured in the presence or absence of insulin and PKA signaling was visualized by immunofluorescence microscopy using an antibody that recognizes proteins specifically phosphorylated by PKA. We found significant decreases in proteins phosphorylated by PKA in wild type ACMs cultured in the absence of insulin. Akita ACMs also had decreased PKA signaling in the absence of insulin and this was not rescued by insulin. The decrease in PKA signaling was observed regardless of whether the kinase was stimulated with a beta-agonist, a cell-permeable cAMP analog, or with phosphodiesterase inhibitors. PKA content was unaffected, suggesting that the decrease in PKA signaling may be occurring by the loss of specific PKA substrates. Phospho-specific antibodies were therefore used to discern which potential substrates may be sensitive to the loss of insulin. Contractile proteins were phosphorylated similarly in wild type and Akita ACMs regardless of insulin. However, phosphorylation of the glycolytic regulator, PFK-2, was significantly decreased in an insulin-dependent manner in wild type ACMs and in an insulin-independent manner in Akita ACMs. These results demonstrate a defect in PKA activation in the diabetic heart, mediated in part by deficient insulin signaling, that results in an abnormal activation of a primary metabolic regulator.

cell biology↗

bioRxiv2018

Potential Application of Bacteriophages in Enrichment Culture for Improved Prenatal Streptococcus agalactiae Screening

Vertical transmission of Streptococcus agalactiae can cause neonatal infections. A culture test in the late stage of pregnancy is used to screen for the presence of maternal S. agalactiae for intrapartum antibiotic prophylaxis. For the test, vaginal-rectal swab sampling is immediately followed by enrichment culture and bacterial identification. In some cases, Enterococcus faecalis competes with and overgrowths S. agalactiae in the enrichment culture. Consequently, the identification test occasionally yields false-negative results. Bacterial viruses, bacteriophages (phages), infect and kill specific host bacteria. In the current study, we explored the feasibility of using phages to minimize the undesirable E. faecalis outgrowth and facilitate S. agalactiae detection in an experimental setting. Phage mixture was prepared using three phages that specifically infect E. faecalis: phiEF24C, phiEF17H, and phiM1EF22. The mixture inhibited the growth of 86.7% (26/30) of E. faecalis strains tested in the enrichment broth. When single strains of E. faecalis and S. agalactiae were inoculated in the enrichment broth containing the phage mixture, bacterial growth was inhibited or facilitated, respectively. Further, several sets of S. agalactiae and E. faecalis strains were co-cultured, and bacteria were detected on chromogenic agar after the enrichment culture. S. agalactiae was dominant after plating a phage mixture-treated co-culture, while it was barely detected after plating the untreated co-culture. Considering these observations, the phage mixture can be employed in the S. agalactiae culture test to increase test accuracy.

microbiology↗