Biology subjects

Ueda, K.

Publications and source records attributed to Ueda, K..

25 records · Page 2Linked to original sources

bioRxiv2020

Suberoyl bis-hydroxamic acid reactivates Kaposis sarcoma-associated herpesvirus through histone acetylation and induces apoptosis in lymphoma cells

Kaposis sarcoma-associated herpesvirus (KSHV) is an etiologic agent of Kaposis sarcoma as well as primary effusion lymphoma (PEL), an aggressive B-cell neoplasm which mostly arises in immunocompromised individuals. At present, there is no specific treatment available for PEL and its prognosis is poor. Lytic replication of KSHV is also associated with a subset of multicentric Castleman diseases. In this study, we found that the histone deacetylase inhibitor suberoyl bis-hydroxamic acid (SBHA) induced KSHV reactivation in PEL cells in a dose-dependent manner. Next-generation sequencing analysis showed that more than 40% of all transcripts expressed in SBHA-treated PEL cells originated from the KSHV genome compared with less than 1% in untreated cells. Chromatin immunoprecipitation assays demonstrated that SBHA induced histone acetylation targeting the promoter region of the KSHV replication and transcription activator gene. However, there was no significant change in methylation status of the promoter region of this gene. In addition to its effect of KSHV reactivation, this study revealed that SBHA induces apoptosis in PEL cells in a dose-dependent manner, inducing cleavage of caspases and expression of proapoptotic factors, including Bim and Bax. These findings suggest that SBHA reactivates KSHV from latency and induces apoptosis through the mitochondrial pathway in PEL cells. Therefore, SBHA can be considered a new tool for induction of KSHV reactivation, and could provide a novel therapeutic strategy against PEL. ImportanceKaposis sarcoma and primary effusion lymphoma cells are latently infected with Kaposis sarcoma-associated herpesvirus (KSHV), whereas KSHV replication is frequently observed in multicentric Castleman disease. Although KSHV replication can be induced by some chemical reagents (e.g. 12-O-tetradecanoylphorbol-13-acetate), the mechanism of KSHV replication is not fully understood. We found that the histone deacetylase inhibitor suberoyl bis-hydroxamic acid (SBHA) induced KSHV reactivation with high efficiency, through histone acetylation in the promoter of the replication and transcription activator gene, compared with 12-O-tetradecanoylphorbol-13-acetate. SBHA also induced apoptosis through the mitochondrial pathway in KSHV-infected cells, with a lower EC50 than measured for viral reactivation. SBHA could be used in a highly efficient replication system for KSHV in vitro, and as a tool to reveal the mechanism of replication and pathogenesis of KSHV. The ability of SBHA to induce apoptosis at lower levels than needed to stimulate KSHV reactivation, indicates its therapeutic potential.

microbiology↗

bioRxiv2020

How predictability affects habituation to novelty?

One becomes accustomed to repeated exposures, even for a novel event. In the present study, we investigated how predictability affects habituation to novelty by applying a mathematical model of arousal that we previously developed, and conducted a psychophysiological experiment to test the model prediction. We formalized habituation to novelty as a decrement in Kullback-Leibler divergence from Bayesian prior to posterior (i.e., information gain) representing arousal evoked from a novel event through Bayesian update. The model predicted an interaction effect between initial uncertainty and initial prediction error (i.e., predictability) on habituation to novelty: The greater the initial uncertainty, the faster the information gain decreases (i.e., the sooner one is habituated). Experimental results using subjective reports of surprise and event-related potential (P300) evoked by visual-auditory incongruity supported the model prediction. Our findings suggest that in highly uncertain situations, repeated exposure to stimuli may enhance habituation to novel stimuli.

neuroscience↗

bioRxiv2020

Redirected tropisms of extracellular vesicles and exomeres yield distinct biodistribution profiles

Extracellular particles (EP) including extracellular vesicles (EVs) and exomeres have been shown to play significant roles in diseases and therapeutic applications. However, their spatiotemporal dynamics in vivo have remained largely unresolved in detail due to the lack of a suitable method. We therefore created a bioluminescence resonance energy transfer (BRET)-based reporter, PalmGRET, to enable pan-EP labelling ranging from exomeres (< 50 nm) to small (< 200 nm) and medium and large (> 200 nm) EVs. PalmGRET emits robust, sustained signals and allows the visualization, tracking and quantification of the EPs from whole-animal to nanoscopic resolutions under different imaging modalities, including bioluminescence, BRET and fluorescence. Using PalmGRET, we show that EPs released by lung metastatic hepatocellular carcinoma (HCC) exhibit lung tropism with varying distributions to other major organs in immunocompetent mice. We further demonstrate that gene knockdown of lung-tropic membrane proteins, solute carrier organic anion transporter family member 2A1 (Slco2a1), alanine aminopeptidase (Cd13) and chloride intracellular channel (Clic1) decreases HCC-EP distribution to the lungs and yields distinct biodistribution profiles. We anticipate that EP-specific imaging, quantitative assays and detailed in vivo characterization to be a starting point for more accurate and comprehensive in vivo models of EP biology and therapeutic design.

cell biology↗

bioRxiv2020

The effects of transcranial direct current stimulation on the brain networks related to creative thinking

Human creative thinking is unique and capable of generating novel and valuable ideas. Recent research has clarified the contribution of different brain networks (default mode network, DN; executive control network; salience network) to creative thinking. However, the effects of brain stimulation on brain networks during creative thinking and on creative performance have not been clarified. The present study was designed to examine the changes in functional connectivity (FC) and effective connectivity (EC) of the large-scale brain network, and the ensuing changes in creative performance, induced by transcranial direct current stimulation (tDCS). Fourteen healthy male students underwent two tDCS sessions, one with actual stimulation and one with sham stimulation, on two separate days. Participants underwent tDCS (anode over the left dorsolateral prefrontal cortex, DLPFC; cathode over the right inferior parietal lobule, IPL) for 20 minutes. Before and after the tDCS session, electroencephalography signals were acquired from 32 electrodes over the whole head during the creative thinking task. On FC analysis, the delta band FC between the posterior cingulate cortex and IPL significantly increased only after real stimulation. We also found that the change of flexibility score was significantly correlated with the change in (i) delta band FC between mPFC and left lateral temporal cortex (LTC) and (ii) alpha band FC between IPL and right LTC. On EC analysis, decreased flow within the DN (from left LTC to right IPL) was observed. Our results reveal that tDCS could affect brain networks, particularly the DN, during creative thinking and modulate key FC in the generation of flexible creative ideas.

neuroscience↗

bioRxiv2019

Evaluation of 3D markerless motion capture accuracy using OpenPose with multiple video cameras

There is a need within human movement sciences for a markerless motion capture system, which is easy to use and suffciently accurate to evaluate motor performance. This study aims to develop a 3D markerless motion capture technique, using OpenPose with multiple synchronized video cameras, and examine its accuracy in comparison with optical marker-based motion capture. Participants performed three motor tasks (walking, countermovement jumping, and ball throwing), with these movements measured using both marker-based optical motion capture and OpenPose-based markerless motion capture. The differences in corresponding joint positions, estimated from the two different methods throughout the analysis, were presented as a mean absolute error (MAE). The results demonstrated that, qualitatively, 3D pose estimation using markerless motion capture could correctly reproduce the movements of participants. Quantitatively, of all the mean absolute errors calculated, approximately 47% were less than 20 mm and 80% were less than 30 mm. However, 10% were greater than 40 mm. The primary reason for mean absolute errors exceeding 40mm was that OpenPose failed to track the participants pose in 2D images owing to failures, such as recognition of an object as a human body segment, or replacing one segment with another depending on the image of each frame. In conclusion, this study demonstrates that, if an algorithm that corrects all apparently wrong tracking can be incorporated into the system, OpenPose-based markerless motion capture can be used for human movement science with an accuracy of 30mm or less.

neuroscience↗

bioRxiv2019

Evolutionary arms-races between host and parasitic RNA replicators in an artificial cell-like system

In the prebiotic evolution, molecular self-replicators are considered to develop into diverse, complex living organisms. The appearance of parasitic replicators is believed inevitable in this process. However, the role of parasitic replicators on prebiotic evolution remains elusive. Here, we demonstrated experimental coevolution of RNA self-replicators (host RNAs) and emerging parasitic replicators (parasitic RNAs) for the first time by using an RNA-protein replication system we had developed. During a long-term replication experiment, a clonal population of the host RNA turned into an evolving host-parasite ecosystem through the continuous emergence of new types of host and parasitic RNAs produced by replication errors. The diversified host and parasitic RNAs exhibited evolutionary arms-race dynamics. The parasitic RNA accumulated unique mutations that the host RNA had never acquired, thus adding a new genetic variation to the whole replicator ensemble. These results provide the first experimental evidence that the coevolutionary interplay between host-parasite molecules play a key role in generating diversity and complexity in prebiotic molecular evolution.

evolutionary biology↗

bioRxiv2019

How ATP is used by P-glycoprotein to export multiple hydrophobic compounds

P-glycoprotein (P-gp; also known as MDR1 or ABCB1) is an ATP-driven multidrug transporter that extrudes various hydrophobic toxic compounds to the extracellular space. P-gp consists of two transmembrane domains (TMDs) that form the substrate translocation pathway and two nucleotide-binding domains (NBDs) that bind and hydrolyze ATP. P-gp takes at least two states during transport; the inward-facing (pre-drug transport) conformation, in which the two NBDs are separated and the two TMDs are open to the intracellular side, and the outward-facing (post-drug transport) conformation, in which the NBDs are dimerized and the TMDs are slightly open to the extracellular side. ATP binding and hydrolysis cause conformational changes between the inward-facing and the outward-facing conformations to translocate substrates across the membrane. However, it remains unclear how ATP is used during these conformational changes in living cells. In this study, we investigated the role of ATP binding and hydrolysis during the conformational changes of human P-gp in living cells by using fluorescence resonance energy transfer (FRET). We show that ATP binding causes the conformational change to the outward-facing state and that ATP hydrolysis and subsequent release of {gamma}-phosphate from both NBDs allow the outward-facing state to return to the original inward-facing state.

biochemistry↗