Biology subjects

Inoue, N.

Publications and source records attributed to Inoue, N..

6 recordsLinked to original sources

bioRxiv2025

Newly Evolved Endogenous Retroviruses Prime the Ovarian Reserve for Activation

Female mammals are born with a finite pool of non-growing oocytes (NGOs) housed in primordial follicles, which form the ovarian reserve that determines reproductive lifespan. Mechanisms underlying the reserves long-term maintenance and subsequent follicular activation remain elusive. Using total RNA sequencing and de novo transcriptome assembly, we first captured the comprehensive oocyte transcriptome across perinatal oogenesis in mice. We show that NGOs establish accessible chromatin at gene regulatory elements--including promoters and enhancers--partly driven by newly evolved endogenous retroviruses (ERVs). In NGOs, epigenetic priming for follicular activation involves prior loading of transcription factors TCF3 and TCF12 and non-phosphorylated form of RNA polymerase II at these sites. This primed state is counteracted by repression via Polycomb Repressive Complex 1-mediated H2AK119 ubiquitylation. We propose that ERV-mediated epigenetic priming underlies the ovarian reserves long-term maintenance and establishes a transcriptionally competent yet repressive configuration that enables rapid gene activation upon oocyte growth.

developmental biology↗

bioRxiv2023

Stress-induced vascular remodeling: novel insight into the role of omega-3 fatty acid metabolite, 4-oxoDHA

BackgroundStress has garnered significant attention as a prominent risk factor for inflammation-related diseases, particularly cardiovascular diseases (CVDs). However, the precise mechanisms underlying stress-driven CVDs remain elusive, thereby impeding the development of effective preventive and therapeutic strategies. MethodsTo explore the correlation between plasma lipid metabolites and depressive states, we conducted a study involving healthy volunteers (n=408). Liquid chromatography (LC)/mass spectrometry (MS)/MS-based lipidomics and the self-rating depression (SDS) scale questionnaire were employed for data collection. In addition, we utilized a mouse model by subjecting mice to restraint stress and investigating the impact of stress on plasma lipid metabolites and vascular remodeling following carotid ligation. In vitro functional and mechanistic studies were performed using macrophages, endothelial cells, and neutrophil cells. ResultsOur findings revealed a significant association between depressive state and reduced plasma levels of 4-oxoDHA, a specific omega-3 fatty acid metabolite regulated by 5-lipoxygenase (LO) in neutrophils in healthy volunteers. In mice, restraint stress led to decreased plasma 4-oxoDHA levels and exacerbated vascular remodeling. Moreover, 4-oxoDHA demonstrated the ability to enhance Nrf2-HO-1 pathways, exerting anti-inflammatory effects on endothelial cells and macrophages. Mechanistically, stress-induced noradrenaline triggered the degradation of 5-LO in neutrophils through the proteasome system, facilitated by dopamine D2-like receptor activation. The reduction in circulating 4-oxoDHA resulted in the downregulation of the Nrf2-HO-1 anti-inflammatory axis and an increase in ICAM-1 expression, vascular permeability, and remodeling. ConclusionsOur study unveiled a novel stress-induced pathway of vascular inflammation, mediated through the regulation of omega-3 fatty acid metabolites. Reduced levels of circulating 4-oxoDHA under stress conditions may serve as a promising biomarker for stress. This understanding of the interplay between neurobiology and lipid metabolism provides a potential avenue for the development of treatments aimed at preventing stress-induced systemic neuroinflammation. Highlights- Our study reveals that stress-induced reduction in circulating levels of a specific omega-3 fatty acid metabolite, 4-oxoDHA, contributes to vascular inflammation. - We have identified a novel pathway that explains how stress promotes systemic vascular inflammation by regulating omega-3 fatty acid metabolites in the circulation. - Our findings provide new evidence for the role of 4-oxoDHA in maintaining Nrf2-ARE-related anti-inflammatory functions in endothelial cells and macrophages.

biochemistry↗

bioRxiv2022

Requirement of sequential hydrolysis by CD73 and ALP for uptake of vitamin B2 into cells

Extracellular hydrolysis of flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) to riboflavin is thought to be important for cellular uptake of vitamin B2 because FAD and FMN are hydrophilic and do not pass the plasma membrane. However, it is not clear whether FAD and FMN are hydrolyzed by cell surface enzymes for vitamin B2 uptake. Here, we show that in human cells, FAD, a major form of vitamin B2 in plasma, is hydrolyzed by CD73 (also called ecto-5' nucleotidase) to FMN, then FMN is hydrolyzed by alkaline phosphatase to riboflavin, which is efficiently imported into cells. This process is impaired on the surface of glycosylphosphatidylinositol (GPI)-deficient cells due to lack of these GPI-anchored enzymes. During culture of GPI-deficient cells with FAD or FMN, hydrolysis of these forms of vitamin B2, intracellular levels of vitamin B2, vitamin B2-dependent pyridoxal 5'-phosphate formation, and mitochondrial functions were significantly decreased compared with those in GPI-restored cells. These results suggest that inefficient uptake of vitamin B2 might account for mitochondrial dysfunction seen in some cases of inherited GPI deficiency.

biochemistry↗

bioRxiv2021

Quantitative assessment of multiple fish species around artificial reefs using environmental DNA metabarcoding

Since the early 1970s, many artificial reefs (ARs) have been deployed in Japanese coastal waters to create fisheries grounds. Recently, researchers began to use environmental DNA (eDNA) methods for biodiversity monitoring of aquatic species. A metabarcoding approach using internal standard DNAs (i.e., quantitative MiSeq sequencing) makes it possible to monitor eDNA concentrations of multiple species simultaneously. This method can improve the efficiency of monitoring AR effects on fishes. Our study investigated distributions of marine fishes at ARs and surrounding stations in the open oceanographic environment of Tateyama Bay, central Japan, using quantitative MiSeq sequencing and echo sounder survey. Using the quantitative metabarcoding method, we found higher quantities of fish eDNAs at the ARs than at surrounding stations and different fish species compositions between them. Comparisons with eco sounder survey also showed positive correlations between fish eDNA concentration and echo intensity, which indicates a highly localized signal of eDNA at each sampling station. These results suggest that quantitative MiSeq sequencing is a promising technique to complement conventional methods to monitor distributions of multiple fish species.

ecology↗

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↗

bioRxiv2019

Complement- and inflammasome-mediated autoinflammation-paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell disorder characterized by complement-mediated hemolysis and thrombosis, and bone marrow failure. Affected cells harbor somatic mutation in X-linked PIGA gene, essential for the initial step in glycosylphosphatidylinositol (GPI) biosynthesis. Loss of GPI biosynthesis results in defective cell-surface expression of GPI-anchored complement regulators CD59 and DAF. The affected stem cells generate many abnormal blood cells after clonal expansion, which occurs under bone marrow failure. Here, we report the mechanistic basis of a disease entity, autoinflammation-paroxysmal nocturnal hemoglobinuria (AIF-PNH), caused by germline mutation plus somatic loss of PIGT on chromosome 20q. A region containing maternally imprinted genes implicated in clonal expansion in 20q-myeloproliferative syndromes was lost together with normal PIGT from paternal chromosome 20. Taking these findings together with a lack of bone marrow failure, the mechanisms of clonal expansion in AIF-PNH appear to differ from those in PNH. AIF-PNH is characterized by intravascular hemolysis and recurrent autoinflammation, such as urticaria, arthralgia, fever and aseptic meningitis. Consistent with PIGTs essential role in synthesized GPIs attachment to precursor proteins, non-protein-linked free GPIs appeared on the surface of PIGT-defective cells. PIGT-defective THP-1 cells accumulated higher levels of C3 fragments and C5b-9 complexes, and secreted more IL-1{beta} than PIGA-defective cells after activation of the complement alternative pathway. IL-1{beta} secretion was dependent upon C5b-9 complexes, accounting for the effectiveness of the anti-C5 drug eculizumab for both intravascular hemolysis and autoinflammation. These results suggest that free GPIs enhance complement activation and inflammasome-mediated IL-1{beta} secretion.

immunology↗