Biology subjects

Waguri, S.

Publications and source records attributed to Waguri, S..

9 recordsLinked to original sources

bioRxiv2026

TGM2-mediated histone serotonylation is an epigenetic cardioprotective mechanism in HFpEF

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome with incompletely understood molecular mechanisms. Histone serotonylation is a recently identified epigenetic modification in which serotonin is covalently conjugated to glutamine 5 of histone H3 in H3K4me3-marked nucleosomes. Here, we investigated the role of transglutaminase 2 (TGM2)-mediated histone serotonylation in HFpEF. In a mouse model of HFpEF induced by salty drinking water, unilateral nephrectomy and aldosterone infusion (SAUNA), cardiac H3K4me3Q5ser and nuclear TGM2 levels were increased. Cardiomyocyte-specific TGM2-deficient mice developed aggravated HFpEF phenotypes after SAUNA exposure, including worsened diastolic dysfunction, reduced exercise capacity, pulmonary congestion and delayed cardiomyocyte relaxation. CUT&RUN sequencing identified H3K4me3Q5ser-enriched regions predominantly around transcription start sites after SAUNA exposure, with notable enrichment at genes associated with G2/M checkpoint-related stress-response signaling. RNA sequencing further showed that activation of this pathway was impaired in SAUNA-exposed TGM2-deficient hearts. In cardiac myocytes, calcium-binding sites and nuclear localization of TGM2 support checkpoint-related stress-response gene activation in cardiac myocytes. Pharmacological WEE1 inhibition, which activates downstream CDK1-associated checkpoint signaling, partially rescued the aggravated HFpEF phenotype in TGM2-deficient mice. Finally, in patients with HFpEF, lower circulating serotonin levels were associated with adverse cardiac outcomes, and cardiomyocyte H3K4me3Q5ser levels correlated with serum serotonin concentrations. These findings suggest that cardiomyocyte TGM2-mediated histone serotonylation represents a stress-adaptive, cardioprotective epigenetic mechanism in HFpEF.

pathology↗

bioRxiv2025

KEAP1 retention in phase-separated p62 bodies drives liver damage in autophagy-deficient conditions

Phase-separated p62 bodies activate NRF2, a key transcription factor for antioxidant response, by sequestering KEAP1, which targets NRF2 for degradation. Although p62 bodies containing KEAP1 are degraded by autophagy, they accumulate in various liver disorders. Their precise disease role remains unclear. We show that excessive KEAP1 retention in p62 bodies and NRF2 activation are major causes of liver damage when autophagy is impaired. In mice with weakened or blocked p62-KEAP1 interactions, KEAP1 retention and NRF2 activation under autophagy-deficient conditions were suppressed. Transcriptome and proteome analyses revealed that NRF2 targets upregulated by autophagy suppression normalized in p62 mutants unable to bind KEAP1. Autophagy deficiency caused organelle accumulation, especially of the ER, regardless of p62 mutation. Liver damage and hepatomegaly from autophagy suppression markedly improved in p62 mutants, particularly those with blocked KEAP1 binding. These findings highlight excessive KEAP1 retention in p62 bodies and defective organelle turnover as key drivers of liver pathology, underscoring the significance of phase separation in vivo.

cell biology↗

bioRxiv2024

Loss of SPNS1, a lysosomal transporter, in the nervous system causes dysmyelination and white matter dysplasia

Protein spinster homolog 1 (SPNS1) is a lysosomal transporter of lysophospholipids and sphingosine, which has recently been identified to be mutated in patients with neurodegeneration. However, its physiological role, especially in the nervous system, remains largely unknown. In this study, we generated, for the first time, nervous system-specific Spns1 knockout mice, Spns1flox/flox;nestin-Cre, and found that the mutant mice develop neurological symptoms, such as epilepsy, and growth retardation, and die by 5 weeks of age. The mutant mice exhibited dysmyelination and oligodendrocyte shedding, while maintaining the neurons. Mutant mouse brains showed accumulation of lysophospholipids, predominantly in regions, such as the olfactory bulb and hippocampus. Furthermore, whereas sphingosine accumulated in the mutant mouse brain, the levels of ceramide and sphingoglycolipids, which are the main myelin components, were decreased. Our findings imply that abnormal sphingosine metabolism causes dysmyelination and white matter dysplasia in brain-specific Spns1-knockout mice, and indicate a possible role of SPNS1 mutation in the pathogenesis of congenital cerebral white matter dysplasia in humans.

cell biology↗

bioRxiv2022

Phosphorylation of phase-separated p62 bodies by ULK1 activates a redox-independent stress response

NRF2 is a transcription factor responsible for antioxidant stress responses that is usually regulated in a redox-dependent manner. p62 bodies formed by liquid-liquid phase separation contain Ser349-phosphorylated p62, which participates in the redox-independent activation of NRF2. However, the regulatory mechanism and physiological significance of phosphorylation remain unclear. Herein, we identify ULK1 as a kinase responsible for phosphorylation of p62. ULK1 co-localizes with p62 bodies, and directly interacts with p62. This phosphorylation allows KEAP1 to be retained within p62 bodies, activating NRF2. p62S351E/+ mice are phosphomimetic knock-in mice in which Ser351 corresponding to human Ser349 is replaced by Glu. These mice, but not phosphodefective p62S351A/S351A mice, exhibit NRF2 hyperactivation and growth retardation, the latter caused by malnutrition and dehydration due to obstruction of the esophagus and forestomach secondary to hyperkeratosis. p62S351E/+ mice are a phenocopy of systemic Keap1-knockout mice. Our results expand our understanding of the physiological importance of the redox-independent NRF2 activation pathway and provide new insight into the role of phase separation in this process.

cell biology↗

bioRxiv2022

Lysosomal vesiculophagy terminates STING signalling

Stimulator of interferon genes (STING) is essential for the type I interferon response against a variety of DNA pathogens1,2. Upon emergence of cytosolic DNA, STING translocates from the endoplasmic reticulum (ER) to the Golgi where STING activates the downstream kinase TBK1, then to lysosome through recycling endosomes (REs) for its degradation3-6. Although the molecular machinery of STING activation is extensively studied and defined7, the one underlying STING degradation has not yet been fully elucidated. Here we show an unanticipated mechanism termed "lysosomal vesiculophagy" dictates STING degradation. Airyscan super-resolution microscopy and correlative light/electron microscopy show that a cluster of STING-positive vesicles of an RE origin are directly encapsulated into lysosome. Screening of mammalian Vps genes, the yeast homologues of which regulate Golgi-to-vacuole transport8, shows that the endosomal sorting complexes required for transport (ESCRT) is essential for the STING encapsulation into lysosome. Knockdown of Tsg101 and Vps4, components of ESCRT9, results in the accumulation of STING vesicles in the cytosol, leading to the sustained type I interferon response. STING undergoes ubiquitination at REs and degradation of STING requires the ubiquitin-binding domain of Tsg101, ensuring the selective degradation of activated STING. Our results reveal a novel mode of autophagy that prevents hyperactivation of innate immune signalling and provide insights into the ER-Golgi-REs-lysosomes pathway for degradation of transmembrane proteins.

cell biology↗

bioRxiv2021

Arf GTPase-Activating proteins SMAP1 and AGFG2 regulate the size of Weibel-Palade bodies and exocytosis of von Willebrand factor

Arf GTPase-Activating proteins (ArfGAPs) mediate the hydrolysis of GTP bound to ADP-ribosylation factors, which are important for intracellular transport. ArfGAPs have been shown to be critical for cargo sorting in the Golgi-to-ER and post-Golgi traffic. However, their roles in the sorting of secretory proteins remains unclear. Weibel-Palade bodies (WPBs) are cigar-shaped secretory granules in endothelial cells that contain von Willebrand factor (vWF) as their main cargo. WPBs are formed at the trans-Golgi Network, and this process is thought to be coupled with the sorting of vWF. WPB biogenesis was reported to be regulated by ADP-ribosylation factors and their regulators, but the role of ArfGAPs has been unknown. In this study, we performed siRNA screening of ArfGAPs to investigate the biogenesis of WPBs. We found two ArfGAPs, SMAP1 and AGFG2, to be involved in WPB size and vWF exocytosis, respectively. SMAP1 depletion resulted in small-sized WPBs, and the lysosomal inhibitor leupeptin recovered the size of WPBs. These results indicate that SMAP1 functions in preventing the degradation of cigar-shaped WPBs. However, AGFG2 downregulation resulted in the inhibition of vWF secretion upon Phorbol 12-myristate 13-acetate (PMA)-stimulation, suggesting that AGFG2 plays a role in vWF exocytosis. Our study revealed unexpected processes regulated by ArfGAPs for vWF transport. Summary StatementThe ArfGAP proteins SMAP1 and AGFG2 were identified as regulating WPB size and vWF exocytosis.

cell biology↗

bioRxiv2020

Homeostatic regulation of STING by Golgi-to-ER membrane traffic

Coat protein complex I (COP-I) mediates the retrograde transport from the Golgi to the ER1,2. Mutation of the COPA gene, encoding one of the COP-I subunits (-COP), causes an immune dysregulatory disease (COPA syndrome)3. The molecular mechanism by which the impaired retrograde transport results in autoinflammation is not understood. Here we report that STING4, an innate immunity protein, is a cargo of the Golgi-to-ER membrane transport. In the presence of the disease-causative -COP variants, STING cannot be retrieved back to the ER from the Golgi. The forced Golgi residency of STING results in the cGAS-independent and palmitoylation-dependent activation of the STING downstream signalling pathway. Surf45, a protein that circulates between the ER and the Golgi, binds STING and -COP, and mediates retrograde transport of STING to the ER. STING/Surf4/-COP complex is disrupted in the presence of the disease-causative -COP variant. Intriguingly, the STING ligand cGAMP also impairs the formation of STING/Surf4/-COP complex. Our results suggest a homeostatic regulation of STING at the resting state by the Golgi-to-ER membrane traffic and provide insights into the pathogenesis of COPA syndrome.

cell biology↗

bioRxiv2019

Autophagy controls lipid droplet formation by fine-tuning NCoR1 levels

Lipid droplets (LDs) are dynamic organelles that store neutral lipids during times of energy excess, such as following a meal. LDs serve as an energy reservoir during fasting and have a buffering capacity that prevents lipotoxicity. Autophagy and the autophagic machinery have been proposed to play a role in LD biogenesis but the underlying molecular mechanism remains unclear. Here, we show that when nuclear receptor co-repressor 1 (NCoR1), which inhibits the transactivation of nuclear receptors, accumulates due to autophagy suppression, LD biogenesis is blocked. Ablation of ATG7, a gene essential for autophagy, suppressed the expression of gene targets of liver X receptor (LXR), a nuclear receptor responsible for fatty acid and triglyceride synthesis in an NCoR1-dependent manner. LD biogenesis in response to fasting and after hepatectomy was hampered by the suppression of autophagy. These results indicate that autophagy controls physiological hepatosteatosis by fine-tuning NCoR1 protein levels.

cell biology↗

bioRxiv2018

Skull base invasive low-grade meningiomas, a distinct genetic subgroup: A microarray gene expression profile analysis.

IntroductionMeningioma is the most common adult primary brain tumor originating from meningeal coverings of the brain and spinal cord. Commonly, World Health Organization (WHO) grade-I meningiomas are slowly growing and surgically curative, some present with clinically aggressive behavior, invading the skull base bone and soft tissues by extending into the extracranial spaces.\n\nMethodsTo detect the genetic background of the Skull Base Invasive Low-grade Meningioma (SBILM), we conducted a comprehensive analysis of gene expression was conducted on 32 meningioma samples.\n\nResultsThe cluster analysis of the gene expression profile demonstrated a distinctive clustering pattern of the SBILM. Based on the clinical behavior and the microarray findings, they might be a distinct subgroup of meningiomas.\n\nConclusionFurther studies on characterization of genes specifically expressed by the SBILM could lead to the development of diagnostic tools, differentiating it from other WHO grade-I meningiomas and assist in the appropriate management and follow-up strategy, and open the door for development of pharmacological therapies.

genomics↗