Biology subjects

Yasunaga, J.-i.

Publications and source records attributed to Yasunaga, J.-i..

8 recordsLinked to original sources

bioRxiv2026

Desialylated platelets promote hepatocyte proliferation via the ERK1/2 signaling pathway

Platelets are increasingly recognized as active regulators of tissue repair and liver regeneration beyond their classical roles in hemostasis and thrombosis. Loss of terminal sialic acid from platelet surface glycoproteins, a process known as desialylation, occurs during platelet aging or activation and has been linked to platelet clearance via the asialoglycoprotein receptor (ASGPR) on hepatocytes. However, the mechanisms by which desialylated platelets (D-plts) directly stimulate hepatocyte proliferation remain poorly understood. This study aimed to elucidate the proliferative effects of D-plts on hepatocytes and to identify the underlying signaling mechanisms. D-plts were generated and co-cultured with hepatocyte models exhibiting low or absent levels of asialoglycoprotein receptor 1 (ASGPR1) expression, including HepG2 cells, HuH-7 cells, and human chemically induced liver progenitors. Hepatocyte proliferation was assessed, and the roles of platelet-derived factors and downstream signaling pathways were investigated. Co-culture with D-plts significantly increased hepatocyte proliferation in all three cell models compared with the corresponding controls. Moreover, supernatants derived from stimulated D-plts also significantly enhanced hepatocyte proliferation, suggesting that soluble platelet-derived factors contribute to this effect. Mechanistically, the proliferative effects were mediated predominantly through the ERK1/2 signaling pathway rather than the JAK-STAT pathway in both hepatocytes co-cultured with D-plts and those treated with D-plt-derived supernatants. In conclusion, our findings demonstrate that D-plts directly promote hepatocyte proliferation through an ASGPR-independent pathway, in which ERK1/2 signaling plays a central role. These results highlight a novel mechanism through which platelet desialylation may contribute to liver regeneration. Graphical Abstract(A) Desialylated platelets are readily activated and release increased amounts of EGF, promoting hepatocyte proliferation via the EGF-ERK signaling pathway. (B) Normal platelets show lower reactivity and reduced EGF release than desialylated platelets, resulting in weaker hepatocyte proliferation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=102 SRC="FIGDIR/small/740293v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@d8eb25org.highwire.dtl.DTLVardef@135e644org.highwire.dtl.DTLVardef@1a0a924org.highwire.dtl.DTLVardef@c092e9_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2025

Dual resistance to cold and ethanol in Penicillium species persistently contaminating donated cadavers

Modern cadaver preservation techniques, such as low-concentration formaldehyde methods, are increasingly adopted to mitigate health risks and improve tissue fidelity for medical education and surgical training. However, these environments potentially foster fungal contamination. This study aimed to identify contaminating species from cadaveric surfaces stored under specific preservation conditions and establish effective countermeasures. Genetic identification revealed Penicillium paneum as the predominant species, while Penicillium corylophilum was also detected. These species exhibited distinctive traits, including vigorous growth at 4{degrees}C and marked ethanol tolerance, that explain their persistence in this preservation environment. Antifungal susceptibility testing demonstrated that these isolates were highly susceptible to commonly used disinfectants such as benzalkonium chloride, chlorhexidine gluconate, and phenol. Our findings indicate that these Penicillium species are uniquely adapted to low-temperature and ethanol-rich preservation environments. The incorporation of the identified disinfectants into preservation solutions offers a practical and effective strategy for controlling persistent fungal contamination in cadaveric facilities.

microbiology↗

bioRxiv2025

Covalent anti-HIV compound that induces HIV-1 capsid multimerization and degradation decomposes the viral core

Covalent inhibitors form strong, essentially irreversible interactions with their targets, offering enhanced structural selectivity within the target cavity and prolonged target engagement even at low doses. Here, we report that ACAi-001, an HIV-1 capsid (CA)-targeting compound identified through in silico screening of the hydrophobic cavity in the CA N-terminal domain (CA-NTD), inhibits HIV-1 replication in cell-based assays. ACAi-001 covalently binds CA to induce aberrant CA multimerization and degradation in vitro, a pharmacological property distinct from that of existing CA inhibitors such as lenacapavir. This mechanism was confirmed by Western blotting (WB), size exclusion chromatography (SEC), differential scanning fluorimetry (DSF), and liquid chromatography-mass spectrometry (LC-MS). These results suggest that ACAi-001, with two putative covalent interactions in its chemical structure, binds directly to Ser16 in the N-terminal domain targeting cavity in addition to Cys198 or Cys218 in the C-terminal domain of CA. The treatment of viral particles with ACAi-001 results in the loss of intact, conical HIV-1 cores, as directly visualized by transmission electron microscopy (TEM), establishing the HIV-1 core as the direct target of ACAi-001. These findings demonstrated that ACAi-001 may be a promising next-generation anti-HIV-1 CA inhibitor with unique mechanisms of action, offering new insight into HIV-1 core assembly and disassembly.

microbiology↗

bioRxiv2025

Machine Learning-based Identification and Characterization of High-risk Carriers of HTLV-1-Associated Myelopathy (HAM)

HTLV-1-associated myelopathy (HAM) develops in a part of HTLV-1-infected individuals while most of the individuals remain asymptomatic. This complicates the identification of HTLV-1 carriers at elevated risk. In this study, we integrated HTLV-1 proviral load and antibody titers against Tax, Env, Gag p15, p19, and p24 proteins in a machine learning (ML) framework to identify and characterize high-risk individuals likely to develop HAM. We stratified asymptomatic carrier samples employing an anomaly detection model. We further developed and validated classifier models capable of distinguishing three clinical subgroups, carrier, ATL, and HAM for assessing the anomaly carrier samples as unseen test data. With most anomaly carrier samples ([~]76.47%) predicted as HAM, further statistical and interpretative analysis revealed the HAM-like characteristics of the anomaly carrier samples indicating elevated risk. Additionally, significant heterogeneity in immune response was observed among other asymptomatic carriers. Our machine learning-based approach offers a novel and insightful tool for identifying and evaluating high-risk characteristics for HAM, providing a holistic view of the complex immune dynamics of asymptomatic carriers of HTLV- 1.

systems biology↗

bioRxiv2024

Antifungal potency of terbinafine as a therapeutic agent against Exophiala dermatitidis in vitro

SynopsisO_ST_ABSBackgroundC_ST_ABSExophiala dermatitidis (E. dermatitidis), which causes skin infections or respiratory diseases, is occasionally fatal in immunocompromised patients. ObjectivesHere, we report the unique antifungal potency of terbinafine (TRB), which targets squalene epoxidase, against E. dermatitidis (SQLEED) using various in vitro approaches. MethodsBased on the human SQLE crystal structure, we created a structure model of SQLEED using SWISS-MODEL and determined the best-fitting model of TRB to the SQLEED. The versatile antifungal activities, including fungicidal activity, biofilm inhibition, biofilm eradication activity, and the combination effect of TRB, posaconazole (PSC), and amphotericin B (AmB) with great antifungal potency against E. dermatitidis were evaluated using crystal violet and cell viability assay. ResultsClinically isolated E. dermatitidis increased most vigorously at 30{degrees}C but decreased at 40{degrees}C. E. dermatitidis hyphae elongated and attached to a cell scaffold, forming a membrane-like biofilm that was distinct from the cell-free biofilm. In the binding model, TRB formed an H-bond with Y102 and was surrounded by key amino acid residues of SQLEED corresponding to TRB-resistant mutations in Trichophyton rubrum, showing an appropriate interaction. Among TRB, PSC, and AmB with potent antifungal activities, TRB and PSC showed more potent antibiofilm activities than AmB. In addition, TRB and PSC exhibited residual potency without incubation against E. dermatitidis, decreasing the growth at lower concentrations than AmB. In contrast, AmB exhibited strong time-dependent killing and eradication activities. The combination of TRB and PSC was more effective than that of TRB and AmB or PSC and AmB in vitro. ConclusionsAlthough the tissue migration of TRB must be considered, these data suggest that TRB and PSC may be useful agents and a potent combination in severely immunocompromised patients with refractory and systemic E. dermatitidis infection.

microbiology↗

bioRxiv2022

Reprogramming of lactate metabolism is linked to the oncogenesis of the virus-induced leukemia

Acceleration of glycolysis is a common trait of cancer. A key metabolite, lactate, is properly secreted from cancer cells, since its accumulation is toxic. Here, we report that a viral oncogene, HTLV-1 bZIP factor (HBZ), bimodally upregulates TAp73 to promote lactate excretion from adult T-cell leukemia-lymphoma (ATL) cells. HBZ protein binds to EZH2 and reduces its occupancy of the TAp73 promoter. Meanwhile, HBZ RNA activates TAp73 transcription via the BATF3-IRF4 machinery. TAp73 upregulates the lactate transporters MCT1 and MCT4. Inactivation of TAp73 leads to intracellular accumulation of lactate, inducing cell death in ATL cells. Furthermore, TAp73 knockout diminished development of inflammation in HBZ-transgenic mice. An MCT1/4 inhibitor, syrosingopine, decreased the growth of ATL cells in vitro and in vivo. MCT1/4 expression was positively correlated with TAp73 in many cancers, and their upregulations were associated with dismal prognosis. Activation of the TAp73-MCT1/4 pathway could be a common mechanism contributing to oncogenesis.

cancer biology↗

bioRxiv2019

Efficient horizontal transmission without viral super-spreaders may cause the high prevalence of STLV-1 infection in Japanese macaques

AbstractsSimian T-cell leukemia virus type-1 (STLV-1) is disseminated among various non-human primate species and is closely related to human T-cell leukemia virus type-1 (HTLV-1), the causative agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. Notably, the prevalence of STLV-1 infection in Japanese macaques (JMs) is estimated to be much greater than that in other non-human primates; however, the mechanism and mode of STLV-1 transmission remain unknown. We hypothesized that a substantial proportion of infected macaques may play a critical role as viral super-spreaders for efficient inter-individual transmission leading to the high prevalence of infection. To address this, we examined a cohort of 280 JMs reared in a free-range facility for levels of anti-STLV-1 antibody titers (ABTs) and STLV-1 proviral loads (PVLs). We found that the prevalence of STLV-1 in the cohort reached up to 65% (180/280), however, the ABTs and PVLs were normally distributed with mean values of 4076 and 0.62%, respectively, which were comparable to those of HTLV-1-infected humans. Contrary to our expectations, we did not observe the macaques with abnormally high PVLs and poor ABTs, and therefore, the possibility of viral super-spreaders was unlikely. Results from further analyses regarding age-dependent changes in STLV-1 prevalence and a longitudinal follow-up of STLV-1 seroconversion strongly suggest that frequent horizontal transmission is a major route of STLV-1 infection, probably due to the unique social ecology of JMs associated with environmental adaptation.\n\nImportanceWe investigated the cause of the high prevalence of STLV-1 infection in the studied JMs cohort. Contrary to our expectations, the potential viral super-spreaders as shown by abnormally high PVLs and poor ABTs were not observed among the JMs. Rather, the ABTs and PVLs among the infected JMs were comparable to those of HTLV-1-infected humans although the prevalence of HTLV-1 in humans is much less than the macaques. Further analyses demonstrate that the prevalence drastically increased over one year of age and most of these animals over 6 years of age were infected with STLV-1, and that in the longitudinal follow-up study frequent seroconversion occurred in not only infants but also in juvenile and adult seronegative monkeys (around 20% per year). This is the first report showing that frequent horizontal transmission without viral super-spreaders may cause high prevalence of STLV-1 infection in JMs.

microbiology↗

bioRxiv2018

Long noncoding RNA ANRIL supports proliferation of adult T-cell leukemia cells through cooperation with EZH2

Adult T-cell leukemia (ATL) is a highly aggressive T-cell malignancy induced by human T-cell leukemia virus type 1 (HTLV-1) infection. Long noncoding RNA (lncRNA) plays a critical role in the development and progression of multiple human cancers. However, the function of lncRNA on HTLV-1-induced oncogenesis has not been elucidated. In the present study, we show that the expression of the lncRNA ANRIL was elevated in HTLV-1 infected cell lines and clinical ATL samples. E2F1 induced ANRIL transcription by enhancing its promoter activity. Knocking down of ANRIL in ATL cells repressed cellular proliferation and increased apoptosis in vitro and in vivo. As a mechanism for these actions, we found that ANRIL targeted EZH2, and activated the NF-{kappa}B pathway in ATL cells. This activation was independent of the histone methyltransferase (HMT) activity of EZH2, but required the formation of an ANRIL/EZH2/p65 ternary complex. Chromatin immunoprecipitation assay revealed that ANRIL/EZH2 enhanced p65 DNA binding capability. In addition, we observed that ANRIL/EZH2 complex repressed p21/CDKN1A transcription through H3K27 trimethylation of the p21/CDKN1A promoter. Taken together, our results implicate that lncRNA ANRIL, by cooperating with EZH2, supports the proliferation of HTLV-1 infected cells, which is thought to be critical for oncogenesis.\n\nIMPORTANCEHuman T-cell leukemia virus type 1 (HTLV-1) is the pathogen that causes adult T-cell leukemia (ATL), which is a unique malignancy of CD4+ T cells. A role for long noncoding RNA (lncRNA) in HTLV-1-mediated cellular transformation has not been described. In this study, we demonstrated that lncRNA ANRIL was important for maintaining proliferation of ATL cells in vitro and in vivo. ANRIL was shown to activate NF-{kappa}B signaling through forming a ternary complex with EZH2 and p65. Further, epigenetic inactivation of p21/CDKN1A was involved in the oncogenic function of ANRIL. To the best of our knowledge, this is the first study to address the regulatory role of the lncRNA ANRIL in ATL and provides an important clue to prevent or treat HTLV-1 associated human diseases.

cancer biology↗