Biology subjects

Sugiura, Y.

Publications and source records attributed to Sugiura, Y..

27 records · Page 2Linked to original sources

bioRxiv2023

Context-Dependent Modification of PFKFB3 in Hematopoietic Stem Cells Promotes Anaerobic Glycolysis and Ensures Stress Hematopoiesis

Metabolic pathways are plastic and rapidly change in response to stress or perturbation. Current metabolic profiling techniques require lysis of many cells, complicating the tracking of metabolic changes over time after stress in rare cells such as hematopoietic stem cells (HSCs). Here, we aimed to identify the key metabolic enzymes that define differences in glycolytic metabolism between steady-state and stress conditions in HSCs and elucidate their regulatory mechanisms. Through quantitative 13C metabolic flux analysis of glucose metabolism using high-sensitivity glucose tracing and mathematical modeling, we found that HSCs activate the glycolytic rate-limiting enzyme phosphofructokinase (PFK) during proliferation and oxidative phosphorylation (OXPHOS) inhibition. Real-time measurement of adenosine triphosphate (ATP) levels in single HSCs demonstrated that proliferative stress or OXPHOS inhibition led to accelerated glycolysis via increased activity of PFKFB3, the enzyme regulating an allosteric PFK activator, within seconds to meet ATP requirements. Furthermore, varying stresses differentially activated PFKFB3 via PRMT1-dependent methylation during proliferative stress and via AMPK-dependent phosphorylation during OXPHOS inhibition. Overexpression of Pfkfb3 induced HSC proliferation and promoted differentiated cell production, whereas inhibition or loss of Pfkfb3 suppressed them. This study reveals the flexible and multilayered regulation of HSC glycolytic metabolism to sustain hematopoiesis under stress and provides techniques to better understand the physiological metabolism of rare hematopoietic cells. Key PointsO_LICombined isotope tracing, mathematical modeling, and single cell ATP analysis enable high-resolution evaluation of blood cell metabolism. C_LIO_LIUnder stress, HSCs quickly accelerate glycolysis to meet ATP demands and maintain hematopoiesis via context-dependent PFKFB3 activation. C_LI

cell biology↗

bioRxiv2023

Cardiomyocyte transcriptomic signatures in response to Trypanosoma cruzi infection underpin Chagas cardiomyopathy progression.

Chagas disease can lead to life-threatening cardiac manifestations that occur more frequently in geographic areas more prevalent with the TcI/II circulating genetic strains. To elucidate the differential transcriptomic signatures of the cardiomyocyte resulting from infection with TcI/II or TcVI T. cruzi strains and explore their relationships with pathogenesis, HL-1 rodent cardiomyocytes were infected with TcI/II or TcVI T. cruzi trypomastigotes. RNA was isolated serially post-infection for microarray analysis. Enrichment analyses of differentially expressed genes (fold-change [≥]2 or [≤] 0.5) highlighted the over-represented biological pathways. We found that Oxidative stress-related GO terms, Hypertrophy model, Apoptosis, and MAPK signaling pathways (all with p<0.01) were upregulated. Glutathione and one-carbon metabolism pathway, and Cellular nitrogen compound metabolic process GO term (all with p <0.001) were upregulated exclusively in the cardiomyocytes infected with the TcI/II strains. Upregulation in the oxidative stress-related and hypertrophic responses are shared hallmarks with viral myocarditis, another inflammatory cardiac pathology. Nitrogen metabolism upregulation and Glutathione metabolism imbalance may implicate the relation of nitrosative stress and poor oxygen radicals scavenging in the unique pathophysiology of chagasic cardiomyopathy development. ImportanceChagas disease affects more than 6 million people worldwide. One-third of those chronically infected will develop the life-threatening condition Chagas Cardiomyopathy (CCM). Trypanosoma cruzi (T. cruzi), grouped based on their genetic variability into six discrete typing units (DTU), are associated with DTU-specific clinical phenotypes. The diverse genetic make-up of parasite virulence factors shall evoke unique host defense responses of variable magnitude, collectively affecting the phenotypic expression of CCM. To address this, we performed a transcriptome analysis of cardiomyocytes infected with three different T. cruzi strains each belonging to a different DTU. As a result, we were able to point out dysregulation in nitrogen metabolic processes, Glutathione, and one-carbon metabolism pathways as main features in the host response against cardiomyopathy-prone T. cruzi strains. Further research on these pathways could serve not only in the lookout for progression biomarkers but also in the lead toward the discovery of new therapeutic targets.

cell biology↗

bioRxiv2022

Quantitative analysis of calcium oxalate monohydrate and dihydrate for elucidating the formation mechanism of calcium oxalate kidney stones

We aimed to identify and quantitatively analyze calcium oxalate (CaOx) kidney stones on the order of micrometers, with a focus on the quantitative identification of calcium oxalate monohydrate (COM) and dihydrate (COD). Fourier Transform Infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), and microfocus X-ray CT measurements (micro-CT) were performed, and the results were compared. The extended analysis method of the FTIR spectrum, focusing on the 780 cm-1 peak, made it possible to achieve a reliable analysis of the COM/COD ratio. We succeeded in the quantitative analysis of COM/COD in the region of 50 x 50 m by microscopic FTIR for thin sections of kidney stones, and by the micro-CT for bulk samples. The extended analysis method of the FTIR spectrum focusing on the 780 cm-1 peak was introduced to analyze the COM/COD ratio. The analysis results based on PXRD measurement with micro sampling, microscopic FTIR analysis of a thin section, and micro-CT observation of a bulk sample of a kidney stone showed roughly consistent results, indicating that all methods can be used complementarily. This quantitative analysis method evaluates the detailed CaOx composition on the preserved stone surface and provides information on the stone formation processes and interactions with organic molecules.

biophysics↗

bioRxiv2022

DNA damage response signaling to mitochondria drives senescence

Cellular senescence is a stress-induced irreversible cell cycle arrest typically accompanied by expression of the cyclin-dependent kinase inhibitor p16INK4a (hereafter referred to as p16) and mitochondrial dysfunction1. Recent studies have indicated that p16-expressing senescent cells accumulate in the body over time and contribute to aging1, 2. Many stresses, such as telomere shortening and oncogene activation, induce senescence by damaging nuclear DNA1. However, the molecular mechanisms linking DNA damage to senescence remain unclear. Here, we show that the outer mitochondrial transmembrane protein BNIP3 drives senescence by triggering a DNA damage response (DDR) of mitochondria. BNIP3 was identified in a genome-wide siRNA screen for genes required for p16 expression upon DNA damage. Mass spectrometric analysis of BNIP3-interacting proteins yielded the DDR kinase ATM and subunits of the mitochondrial contact site and cristae organizing system (MICOS) complex. BNIP3 is an ATM substrate that increases the number of mitochondrial cristae upon DNA damage. This increase enhances the oxidation of fatty acids to acetyl-CoA, an acetyl group donor, thereby promoting histone acetylation and associated p16 expression. Our findings indicate that DDR signaling to mitochondria promotes p16 expression by altering mitochondrial structure and metabolism and highlight the importance of nuclear-mitochondrial communication in senescence induction.

cell biology↗

bioRxiv2020

Senescent cell death as an aging resistance mechanism in naked mole-rat

Naked mole-rats (NMRs) are the longest-lived rodents, showing minimal aging phenotypes. An unsolved paradox is that NMRs exhibit low intracellular anti-oxidant defence despite minimal aging. Here, we explained a link between these “contradicting” features by a phenomenon termed “senescent cell death (SCD)”—Senescence induced cell death in NMR cells due to their inherent vulnerability to reactive oxygen species and unique metabolic system. In NMR skin, we observed few senescent cells during aging or after ultraviolet irradiation, suggesting suppression of senescent cell accumulation in NMR tissue. We discovered that senescent NMR-fibroblasts induce SCD through retinoblastoma protein activation accompanied by autophagy dysregulation, increased oxidative damage and accelerated H2O2-releasing metabolic pathways. During senescence, NMR cells showed resistance to metabolic remodelling unlike mice. Our findings provide mechanistic insights into how extraordinary aging resistance is accomplished in NMR. This will contribute to the development of senolytic drugs to regulate age-related diseases.Competing Interest StatementThe authors have declared no competing interest.View Full Text

cell biology↗

bioRxiv2020

Visualizing ATP Dynamics in Live Mice

ABSTRACTAnalysis of the dynamics of adenosine triphosphate (ATP) is vital to quantitatively define the actual roles of ATP in biological activities. Here, we applied a genetically encoded Förster resonance energy transfer biosensor “GO-ATeam” and created a transgenic mouse model that allows systemic ATP levels to be quantitatively, sensitively, noninvasively, and spatiotemporally measured under physiological and pathological conditions. We used this model to readily conduct intravital imaging of ATP dynamics under three different conditions: during exercise, in all organs and cells; during myocardial infarction progression; and in response to the application of cardiotoxic drugs. These findings provide compelling evidence that the GO-ATeam mouse model is a powerful tool to investigate the multifarious functions of cellular ATP in vivo with unprecedented spatiotemporal resolution in real-time. This will inform predictions of molecular and morphological responses to perturbations of ATP levels, as well as the elucidation of physiological mechanisms that control ATP homeostasis.One Sentence Summary Intravital real-time imaging of ATP dynamics in multiple organs using GO-ATeam mice, can be used to quantitatively, sensitively, noninvasively, and spatiotemporally measure systemic ATP levels and provide a platform for preclinical pharmacological studies.Competing Interest StatementM.Yamamoto is involved in a pending patent related to GO-ATeam mice. H.I. holds a patent for ATeam probe. All other authors declare no competing interests.View Full Text

physiology↗

bioRxiv2020

Prostaglandin in the ventromedial hypothalamus regulates peripheral glucose metabolism

The hypothalamus plays a central role in monitoring and regulating systemic glucose metabolism. The brain is enriched with phospholipids containing poly-unsaturated fatty acids, which are biologically active in physiological regulation. Here, we show that intraperitoneal glucose injection induced changes in hypothalamic distribution and amount of phospholipids, especially arachidonic-acid-containing phospholipids, that were then metabolized to produce prostaglandins. Knockdown of cytosolic phospholipase A2 (cPLA2), a key enzyme for generating arachidonic acid from phospholipids, in the hypothalamic ventromedial nucleus (VMH), lowered insulin sensitivity in muscles during regular chow diet (RCD) feeding. Conversely, the down-regulation of glucose metabolism by high fat diet (HFD) feeding was improved by knockdown of cPLA2 in the VMH through changing hepatic insulin sensitivity and hypothalamic inflammation. Our data suggest that cPLA2-mediated hypothalamic phospholipid metabolism is critical for controlling systemic glucose metabolism during RCD, while continuous activation of the same pathway to produce prostaglandins during HFD deteriorates glucose metabolism.

physiology↗

bioRxiv2019

Myristate as a carbon and energy source for the asymbiotic growth of the arbuscular mycorrhizal fungus Rhizophagus irregularis

Arbuscular mycorrhizal (AM) fungi, forming symbiotic associations with land plants, are obligate symbionts that cannot complete their natural life cycle without a host. Recently, fatty acid auxotrophy of AM fungi is supported by studies showing that lipids synthesized by the host plants are transferred to the fungi and that the latter lack genes encoding cytosolic fatty acid synthases (1-7). Therefore, to establish an asymbiotic cultivation system for AM fungi, we tried to identify the fatty acids that could promote biomass production. To determine whether AM fungi can grow on medium supplied with fatty acids or lipids under asymbiotic conditions, we tested eight saturated or unsaturated fatty acids (C12-C18) and two {beta}-monoacylglycerols. Only myristate (C14:0) led to an increase in biomass of Rhizophagus irregularis, inducing extensive hyphal growth and formation of infection-competent secondary spores. However, such spores were smaller than those generated symbiotically. Furthermore, we demonstrated that R. irregularis can take up fatty acids in its branched hyphae and use myristate as a carbon and energy source. Myristate also promoted the growth of Rhizophagus clarus and Gigaspora margarita. Finally, mixtures of myristate and palmitate accelerated fungal growth and induced a substantial change in fatty acid composition of triacylglycerol compared with single myristate application, although palmitate was not used as a carbon source for cell wall biosynthesis in this culture system. In conclusion, here we demonstrate that myristate boosts asymbiotic growth of AM fungi and can also serve as a carbon and energy source. Significance statementThe origins of arbuscular mycorrhizal (AM) fungi, which form symbiotic associations with land plants, date back over 460 million years ago. During evolution, these fungi acquired an obligate symbiotic lifestyle, and thus depend on their host for essential nutrients. In particular, fatty acids are regarded as crucial nutrients for the survival of AM fungi owing to the absence of genes involved in de novo fatty acid biosynthesis in the AM fungal genomes that have been sequenced so far. Here, we show that myristate initiates AM fungal growth under asymbiotic conditions. These findings will advance pure culture of AM fungi.

microbiology↗

bioRxiv2018

Identification of PTBP1 responsible for caspase dependent YRNA cleavage

Some RNAs such as 28S rRNA, U1 snRNA, and Y RNAs are known to be cleaved during apoptosis. As the underlying mechanism is yet unclear, the functions and biological significance of RNA degradation in apoptosis remain elusive. We previously identified novel, functional small RNAs named AGO-taxis small RNA (ASR) that are specifically bound to AGO1. Here, we investigated ASR biogenesis, which appears to be non-canonical. Y RNAs, non-coding RNAs degraded during apoptosis, were identified as the precursors of several ASRs. Cell-free analysis combined with fractionation methods revealed that the apoptosis-specific biogenesis of ASRs or Y RNA degradation was induced by PTBP1--an endoribonuclease inhibitor of Y RNAs. PTBP1, a splicing factor, was truncated by caspase 3, which subsequently activated endoribonuclease to induce biogenesis of ASRs and Y RNA cleavage.

molecular biology↗