Biology subjects

Horie, T.

Publications and source records attributed to Horie, T..

6 recordsLinked to original sources

bioRxiv2024

A novel VCP modulator, KUS121, attenuates atherosclerosis progression by maintaining intracellular ATP and mitigating ER stress in endothelial cells

BackgroundEndoplasmic reticulum (ER) stress signaling pathways have pivotal roles in atherosclerosis progression. Recently, we have developed Kyoto University Substance (KUS) 121, which selectively inhibits ATPase activities of valosin-containing protein (VCP) and consequently saves intracellular ATP consumption and mitigates ER stress. Methods and ResultsWe assessed the efficacy of KUS121 against atherosclerosis by its daily injection into Apoe-/- mice fed with Western Diet (WD) for 8 weeks. Consequently, KUS121 treatment reduced atherosclerosis progression by approximately 40% in atherosclerotic plaques. Interestingly, we found that C/EBP homologous protein (CHOP), an established ER stress marker, was mainly expressed in plaque endothelium. Therefore, we assessed the action of KUS121 in endothelial cells using the human endothelial cell line (EA.hy926 cells). As a result, KUS121 prevented ER stress-induced apoptosis and downregulated the IRE1 (Inositol-requiring enzyme) -associated inflammatory pathways. Consistent with these in vitro findings, KUS121 treatment also significantly reduced endothelial apoptosis assessed by TUNEL staining and inflammation examined by immunostaining of Nuclear factor kappa B (NF-{kappa}B) and Intercellular adhesion molecule (ICAM) 1 at plaque endothelium. We also demonstrated that KUS121 maintained ATP levels in EA.hy926 cells and atherosclerotic plaque lesions using the single-wavelength or the FRET-based fluorescent ATP sensor. Supplementation of intracellular ATP by Methyl pyruvate (MePyr) attenuated ER stress-induced apoptotic and inflammatory pathways in endothelial cells, which could be the main mechanism how KUS121 reduces ER stress. ConclusionsKUS121 can be a new therapeutic option for atherosclerotic diseases by maintaining intracellular ATP levels and attenuating ER stress-induced apoptosis and inflammation in plaque endothelium.

pathology↗

bioRxiv2024

Stimulatory and inhibitory G-protein signaling relays drive cAMP accumulation for timely metamorphosis in the chordate Ciona

Larvae of the ascidian Ciona initiate metamorphosis tens of minutes after adhesion to a substratum via their adhesive organ. The gap between adhesion and metamorphosis initiation is suggested to ensure the rigidity of adhesion, allowing Ciona to maintain settlement after losing locomotive activity through metamorphosis. The mechanism producing the gap is unknown. Here, by combining gene functional analyses, pharmacological analyses, and live imaging, we propose that the gap represents the time required for sufficient cAMP accumulation to trigger metamorphosis. Not only the Gs pathway but also the Gi and Gq pathways are involved in the initiation of metamorphosis in the downstream signaling cascade of the neurotransmitter GABA, the known initiator of Ciona metamorphosis. The mutual crosstalk of stimulatory and inhibitory G-proteins functions as the accelerator and brake for cAMP production, ensuring the faithful initiation of metamorphosis at an appropriate time and in the right situation.

developmental biology↗

bioRxiv2022

Error-acceptable vertical transmission fostered uncoupled phylogenetic relationships between longicorn beetles and their symbionts

The Coleoptera Cerambycidae (longicorn beetles) use wood under different states (living healthy, freshly snapped, completely rot, etc.) in a species-specific manner for their larval diet. Larvae of some Cerambycidae groups have mycetomes, accessory organs associated with the midgut that harbor fungal symbiont cells. The symbionts are thought to improve nutrient conditions; however, this has yet to be shown experimentally. To deduce the evolutionary history of this symbiosis, we investigated the characteristics of the mycetomes in the larvae of longicorn beetles collected in Japan. Lepturinae, Necydalinae, and Spondylidinae are the only groups that possess mycetomes, and these three groups mycetomes and corresponding fungal cells exhibit different characteristics between the groups. However, the phylogenetic relationship of symbiont yeasts does not coincide with that of the corresponding longicorn beetle species, suggesting they have not co-speciated. The imperfect vertical transmission of symbiont yeasts from female to offspring is a mechanism that could accommodate the host-symbiont phylogenetic incongruence. Some Lepturinae species secondarily lost mycetomes. The loss is associated with their diet choice, suggesting that different conditions between feeding habits could have allowed species to discard this organ. We found that symbiont fungi encapsulated in the mycetomes are dispensable for larval growth if sufficient nutrients are given, suggesting that the role of symbiotic fungi could be compensated by the food larvae take. Aegosoma sinicum is a longicorn beetle classified to the subfamily Prioninae, which does not possess mycetomes. However, this species contains a restricted selection of yeast species in the larval gut, suggesting that the symbiosis between longicorn beetles and yeasts emerged before acquiring the mycetomes.

ecology↗

bioRxiv2021

SMURF2 phosphorylation at Thr249 modifies the stemness and tumorigenicity of glioma stem cells by regulating TGF-β receptor stability

Glioma stem cells (GSCs) contribute to the pathogenesis of glioblastoma, the most malignant form of glioma. The implication and underlying mechanisms of SMAD specific E3 ubiquitin protein ligase 2 (SMURF2) on the GSC phenotypes remain unknown. We previously demonstrated that SMURF2 phosphorylation at Thr249 (SMURF2Thr249) activates its E3 ubiquitin ligase activity. Here, we demonstrate that SMURF2Thr249 phosphorylation plays an essential role in maintaining GSC stemness and tumorigenicity. SMURF2 silencing augmented the self-renewal potential and tumorgenicity of patient-derived GSCs. The SMURF2Thr249 phosphorylation level was low in human glioblastoma pathology specimens. Introduction of the SMURF2T249A mutant resulted in increased stemness and tumorgenicity of GSCs, recapitulating the SMURF2 silencing. Moreover, the inactivation of SMURF2Thr249 phosphorylation increases TGF-{beta} receptor (TGFBR) protein stability. Indeed, TGFBR1 knockdown markedly counteracted the GSC phenotypes by SMURF2T249A mutant. These findings highlight the importance of SMURF2Thr249 phosphorylation in maintaining GSC phenotypes, thereby demonstrating a potential target for GSC-directed therapy.

cancer biology↗

bioRxiv2021

One pair of motor neurons provokes early spontaneous motor behavior through periodic bursting in the chordate ascidian embryo

Vertebrate rhythmic motor behaviour is generated by the central pattern generator (CPG) located in the spinal cord. However, the development of the CPG has not been elucidated at the single-neuron level. We found that a single pair of motor neurons (A10.64/MN2) constitutes the CPG and regulates rhythmic early motor behaviour in the proto-chordate, Ciona. This pair of cells exhibited Ca2+ oscillation with an 80-sec interval at the mid-tailbud stage and 25 sec at the late tailbud stage. The Ca2+ oscillation occurred independently in a dissociated single cell. In the late tailbud stage, the Ca2+ oscillation began to coincide in phase with the ipsilateral tail muscle contraction, which corresponds to rhythmic early motor behaviour. Interestingly, the number and frequency of tail muscle contractions gradually coincided with spikes in the burst of membrane potential as the embryos developed toward late tailbud stage. Photoablation of A10.64/MN2 abolished the rhythmic early motor behaviour. These findings indicate that the early spontaneous rhythmic motor behaviour of Ciona is directly regulated by A10.64/MN2 as an essential component of the CPG. Our findings shed light on the development and evolution of chordate rhythmic behaviours.

developmental biology↗

bioRxiv2020

Cellular identity and Ca2+ signaling activity of the non-reproductive GnRH system in the Ciona larva

Tunicate larvae have a non-reproductive gonadotropin-releasing hormone (GnRH) system with multiple ligands and receptor heterodimerization enabling complex regulation. In the Ciona larva, one of the gnrh genes, gnrh2, is conspicuously expressed in the motor ganglion and nerve cord, which are homologous structures to the hindbrain and spinal cord, respectively, of vertebrates. The gnrh2 gene is also expressed in the proto-placodal sensory neurons, which are the proposed homologue of vertebrate olfactory neurons. The tunicate larvae occupy a non-reproductive dispersal stage, yet the role of their GnRH system remains elusive. In this study, we investigated neuronal types of gnrh2-expressing cells in Ciona larvae and visualized the activity of these cells by fluorescence imaging using a calcium sensor protein. Some cholinergic neurons and dopaminergic cells express gnrh2, suggesting that GnRH plays a role in controlling swimming behavior. However, none of the gnrh2-expressing cells overlap with glycinergic or GABAergic neurons. A role in motor control is also suggested by the correlation between the activity of some gnrh2-expressing cells and tail movements. Interestingly, gnrh2-positive ependymal cells in the nerve cord, known as a kind of glia cells, actively produced Ca2+ transients, suggesting that neuroendocrine signaling occurs in the glia cells of the nerve cord.

neuroscience↗