Biology subjects

Kanno, S.

Publications and source records attributed to Kanno, S..

7 recordsLinked to original sources

bioRxiv2025

Non-DNA-damaging DNA-PK activation improving hearing and prolonging life due to NAD+ and SIRT upregulation

Emerging evidence strongly supports a close relationship between age-related hearing loss and frailty, highlighting the importance of early detection and intervention. Recently, we invented a mitochondria-homing drug named mitochonic acid 5 (MA-5), that increases the adenosine triphosphate (ATP) levels, rescue mitochondrial function, and protect tissue damages. Currently, the phase I clinical trial has been finished in Japan (jRCT2031210495) and the phase 2 clinical trial has already been approved by PMDA. Here we show that MA-5 improved various types of hearing loss in mouse models. Structural chemical bioanalysis revealed that MA-5 is a mixture of equal amount of S- and R- enantiomer and both S- and R- enantiomer increase ATP by binding mitochondrial protein, mitofilin. However, S-enantiomer significantly increased the NAD+ levels by binding to the NAD+-producing key enzyme nicotinamide phosphoribosyltransferase (NAMPT). Moreover, the S-enantiomer increased the sirtuin 1 protein by suppressing polyubiquitination induced by tripartite motif containing 28 (TRIM28) phosphorylation which was triggered by DNA-dependent protein kinase (DNA-PK) activation in the absence of DNA damage. Transcriptomic signatures showed that the signature of MA-5 shows an inverse correlation with aging and mortality and is oriented in the same direction as the OSKM-related iPSCs, suggesting the modification of aging pathways. Oral administration of MA-5 to mitochondrial disease model mouse showed increased survival. Our findings suggest that, in addition to enhancing ATP levels, the coordinated regulation of NAD+ metabolism, SIRT protein expression, and DNA-PK activity-constituting a novel therapeutic triad may contribute to the amelioration of hearing impairment and mitochondrial dysfunction, thereby improving life prognosis.

cell biology↗

bioRxiv2024

Formation of stress granules and non-canonical survival responses in arsenite-exposed cells.

The concentration-dependent decrease in viable cells is a well-documented phenomenon in cytotoxicity assays for most toxic substances. We report that arsenite (As3+), a widely recognized oxidative toxicant, exhibited lower cytotoxic effects at 300 {micro}M compared to 100 {micro}M As3+ in CHO-K1 and Jurkat cells. Formation of stress granules (SGs), which appear in the cytoplasm shortly after exposure to hypertonicity, heat shock, and high concentrations of As3+ is considered as a pro-survival cellular event. We hypothesized that unusual cytotoxicity profile of As3+ could be attributed to SG formation. In both CHO-K1 and Jurkat cells stably expressing GFP-tagged G3BP1, SGs were more rapidly and distinctly induced by 300 {micro}M As3+ than 100 {micro}M As3+. Other toxic metals and a metalloid such as Cd2+, Cu2+, Ag+, and Se4+ did not clearly induce SG formation and instead reduced the viability in a concentration-dependent manner. Exposure to As3+ led to phosphorylation of eIF2, a key regulator of polysome stability and a hallmark of SG formation. Depletion of intracellular glutathione (GSH) increased the susceptibility of cells to As3+, highlighting its role in cellular defense mechanisms. Exposure to As3+ activated small ubiquitin-like modifier (SUMO) which is implicated in phase separation. However, neither depletion of GSH nor overexpression of SUMO contributed As3+-induced SG formation. Consistently, THP-1 and HL60 cells exposed to As3+ also exhibited non-canonical cytotoxic features, albeit at higher concentrations (1 mM). These findings underscore the need for further mechanistic investigations into As3+-induced SG formation, given that As3+ is a promising anti-cancer agent, and resistance of tumor cells to As3+ is a critical issue.

cell biology↗

bioRxiv2024

Phosphate Starvation-Induced CORNICHON HOMOLOG 5 as Endoplasmic Reticulum Cargo Receptor for PHT1 Transporters in Arabidopsis

Inorganic phosphate (Pi) is essential for plant growth and is acquired and distributed by the plasma membrane PHOSPHATE TRANSPORTER 1 proteins (PHT1s). Enhancing the abundance of PHT1s at the cell surface thus ensures plant productivity and sustainable agriculture. CORNICHON HOMOLOG proteins (CNIHs) are conserved eukaryotic cargo receptors that mediate the selective endoplasmic reticulum (ER) export of membrane proteins. In this study, we identified the Arabidopsis thaliana CNIH5 (AtCNIH5) as a Pi starvation-inducible gene, preferentially expressed in vascular tissues and outer root cell layers above the meristem. AtCNIH5 co-localizes to the AtSAR1A/AtSEC16A/AtSEC24A-labeled ER exit sites and interacts with AtPHT1;1. Loss of AtCNIH5 confers reduced shoot Pi levels under Pi sufficiency due to the reduced translocation of Pi from roots to shoots, as well as decreased Pi uptake under Pi deficiency. The cnih5 mutant exhibits decreased abundance of AtPHT1s but increased PHOSPHATE TRANSPORTER TRAFFIC FACILITATOR1 (AtPHF1), which enables the ER exit of PHT1s. The cnih5 mutant also shows a lower plasma membrane targeting efficiency of split-GFP tagged-AtPHT1;1 in the root hair and the epidermis within the root transition/elongation zone. Consistently, dysfunctional AtCNIH5 exerts a suppressive effect on the growth of phf1 and alleviates Pi toxicity in the Pi overaccumulator pho2. However, the in vivo protein-protein interaction and degradation assays indicated that AtCNIH5 is not a direct target of AtPHO2. Our findings unveil that AtCNIH5 is a low Pi-responsive ER cargo receptor that interplays with AtPHF1 to promote the plasma membrane targeting of AtPHT1s in a cell-type-dependent manner.

plant biology↗

bioRxiv2023

Defense-related callose synthase PMR4 promotes root hair callose deposition and adaptation to phosphate deficiency in Arabidopsis thaliana

Plants acquire phosphorus (P) primarily as inorganic phosphate (Pi) from the soil. Under Pi deficiency, plants induce an array of physiological and morphological responses, termed phosphate starvation response (PSR), thereby increasing Pi acquisition and use efficiency. However, the mechanisms by which plants adapt to Pi deficiency remain to be elucidated. Here, we report that deposition of a {beta}-1,3-glucan polymer called callose is induced in Arabidopsis thaliana root hairs under Pi deficiency, in a manner independent of PSR-regulating PHR1/PHL1 transcription factors and LPR1/LPR2 ferroxidases. Genetic studies revealed PMR4 (GSL5) callose synthase being required for the callose deposition in Pi-depleted root hairs. Loss of PMR4 also reduces Pi acquisition in shoots and plant growth under low Pi conditions. The defects are not recovered by simultaneous disruption of SID2, mediating defense-associated salicylic acid (SA) biosynthesis, excluding SA defense activation from the cause of the observed pmr4 phenotypes. Grafting experiments and characterization of plants expressing PMR4 specifically in root hair cells suggest that a PMR4 pool in the cell type contributes to shoot growth under Pi deficiency. Our findings thus suggest an important role for PMR4 in plant adaptation to Pi deficiency. Significance statementWe reveal that PMR4 callose synthase mediates callose deposition in root hairs under phosphate (Pi) deficiency, without requiring Pi starvation response regulators PHR1/PHL1 or LPR1/LPR2. The loss of the callose deposition is accompanied by decreases in Pi acquisition and plant growth in pmr4. Root hair cell-specific PMR4 expression restores callose deposition in root hairs and shoot growth under Pi deficiency, indicating a critical role for root hair callose in plant adaptation to Pi deficiency.

plant biology↗

bioRxiv2023

Macrophage Receptor with collagenous structure (MARCO) recognizes the cellular protein corona formed on environmental particles

Several difficulties hamper the toxicological evaluation of particulate substances in vitro. One of the most serious difficulties is that most particles are insoluble in water, and easily agglomerate during the assay. Albumin and some detergents have been used to disperse the particles in the culture medium. However, effects of these additives on the cellular uptake of particles and the following biological consequences are unknown. The first event when phagocytic cells encounter particulate substances is an association of the plasma membrane with the particle surface. Macrophage receptor with collagenous structure (MARCO) has been identified as a receptor for environmental particles such as titanium dioxide (TiO2) and carbonaceous particles. However, it remained to be revealed how MARCO recognizes the unopsonized particles. While investigating the particle surface-cell membrane interaction using GFP-tagged MARCO-expressing cells, we found that cytosolic proteins were released from the cells and rapidly adsorbed on the surface of TiO2 particles. The GFP-tagged MARCO-overexpressing cells were further engineered to express RFP-tagged LC3 (cytosolic protein) to visualize adsorption of proteins on the surface of titanium dioxide (TiO2) particles. We found that cytosolic proteins including LC3 were released in the culture medium from intact cells and adsorbed on the particle surface quickly in the cell culture system. These results indicate that MARCO probably recognizes adsorbed intracellular proteins rather than the uncoated inorganic surface of environmental particles.

cell biology↗

bioRxiv2020

Visualization of seasonal shifts of phosphorus re-translocation and overwintering recycling in a shortened annual cycle system of the deciduous poplar tree (Populus alba L.).

Phosphorus (P) is an essential macronutrient for plant growth. In deciduous trees, P is remobilized from senescing leaves and stored in perennial tissues during winter for further growth. Annual internal recycling and accumulation of P is considered an important strategy to support vigorous growth of trees. However, the pathways of seasonal re-translocation of P and the molecular mechanisms of this transport have not been clarified. Here we show the seasonal P re-translocation route visualized using the real-time radioisotope imaging and the macro- and micro-autoradiography. We analyzed the seasonal re-translocation P in poplar (Populus alba. L) cultivated under "a shortened annual cycle system", which mimicked seasonal phenology in a laboratory. From growing to senescing season, sink tissues of 32P and/or 33P shifted from young leaves and the apex to the lower stem and roots. The radioisotope P re-translocated from a leaf was stored in phloem and xylem parenchyma cells and redistributed to new shoots after dormancy. Seasonal expression profile of phosphate transporters (PHT1, PHT5 and PHO1 family) was obtained in the same system. Our results reveal the seasonal P re-translocation routes at the organ and tissue levels and provide a foothold for elucidating its molecular mechanisms.

plant biology↗

bioRxiv2020

Disruption of AtHAK/KT/KUP9 enhances plant cesium accumulation under low potassium supply

Understanding molecular mechanisms which underlie transport of cesium (Cs+) in plants is important to limit entry of its radioisotopes from contaminated area to the food chain. The potentially toxic element Cs+, which is not involved in any biological process, is chemically closed to the macronutrient potassium (K+). Among the multiple K+ carriers, the high-affinity K+ transporters family HAK/KT/KUP is thought to be relevant in mediating opportunistic Cs+ transport. On the 13 KUP identified in Arabidopsis thaliana, only HAK5, the major contributor to root K+ acquisition under low K+ supply, has been functionally demonstrated to be involved in Cs+ uptake in planta. In the present study, we showed that accumulation of Cs+ increased by up to 30% in two A. thaliana mutant lines lacking KUP9 and grown under low K+ supply. Since further experiments revealed that Cs+ release from contaminated plants to the external medium is proportionally lower in the two kup9 mutants, we proposed that KUP9 disruption could impair Cs+ efflux. By contrast, we did not measure significant impairment of K+ status in kup9 mutants suggesting that KUP9 disruption does not alter substantially K+ transport in experimental conditions used here. Putative primary role of KUP9 in plants is further discussed.

plant biology↗