Biology subjects

Higuchi, M.

Publications and source records attributed to Higuchi, M..

At least 19 recordsLinked to original sources

bioRxiv2026

USP10 Facilitates Homologous Recombination-Mediated DNA Double-Strand Break Repair through Localization to the Nucleolus

Ubiquitin-specific protease 10 (USP10) is a multifunctional deubiquitinating enzyme that primarily regulates cellular stress responses, including the DNA damage response. Here, we show that USP10 is required for homologous recombination (HR)-mediated repair of DNA double-strand breaks (DSBs) and for the maintenance of genomic stability. USP10-depleted cells exhibit spontaneous micronuclei, impaired DSB repair following zeocin and camptothecin treatment, and reduced sister chromatid exchange. These cells are also more sensitive to irradiation and mitomycin C and display increased chromosomal abnormalities after mitomycin C treatment. Persistent RAD51 foci formation in USP10-depleted cells suggests that USP10 functions at a step downstream of RAD51 nucleofilament formation. This function of USP10 in facilitating HR repair depends on deubiquitinase activity but is independent of G3BP1/2 and PABP binding. In addition, a newly identified nucleolar localization signal is required for USP10s function in DSB repair. Together, these findings indicate that USP10 maintains genome integrity by localizing to the nucleolus and facilitating HR-mediated repair of DSBs.

cell biology↗

bioRxiv2026

Dopamine shapes brain metastate dynamics

Dopamines influence on large-scale network dynamics, especially on the default mode network (DMN), remains uncertain, as fMRI studies have produced mixed results. One likely contributor to these discrepancies is reliance on traditional functional connectivity analyses, which typically derive a single metric (e.g., the Pearson correlation coefficient) from the entire time series and thus fail to capture network dynamics. To address this issue, we combined a dopaminergic challenge (mazindol, a dopamine transporter [DAT] reuptake inhibitor), PET, resting-state fMRI, and hidden Markov modeling (HMM) to characterize time-varying alterations in human large-scale functional networks following acute DAT blockade. We found that mazindol-induced increases in endogenous dopamine altered the balance between the brains functional "metastates," two recurrent higher-order network configurations that each encompass multiple HMM-derived brain states. Mazindol increased the time participants spent in an internally oriented cognitive metastate and decreased the time spent in a sensorimotor-perceptual metastate, with the DMN showing the most pronounced lengthening. In exploratory analyses, declines in [{superscript 1}{superscript 1}C]raclopride binding, a PET index of D2 dopamine receptor availability reflecting increased striatal extracellular dopamine levels, tended to show a positive correlation with the prolongation of these cognitive states. These findings indicate that dopamine is closely linked to shifts from sensorimotor and perceptual to cognitive brain metastates, potentially underpinning the prioritization of internally oriented over externally driven psychological processes. Our results highlight the importance of dynamic, time-resolved connectivity approaches for understanding neuromodulatory actions in the human brain and suggest that dopamine helps regulate the dynamic balance between functionally competing large-scale brain networks.

neuroscience↗

bioRxiv2025

FSP1 and histone deacetylases suppress cancer persister cell ferroptosis

Cancer persister cells populate minimal residual disease and contribute to acquired drug resistance. We previously discovered that persister cells are sensitized to ferroptosis. However, our understanding of this emergent persister cell vulnerability remains limited, impeding ferroptosis drug development efforts. Here, we sought to understand key factors which govern persister cell ferroptosis to inform combinatorial treatment strategies. We found that persister cells can downregulate oxidative phosphorylation, a key source of reactive oxygen species, to avoid death from GPX4 inhibition. However, this can be overcome by pretreatment with clinically available histone deacetylase inhibitors which induce reactive oxygen species in persister cells and synergize with GPX4 inhibition. Furthermore, we found that while levels of iron, glutathione, and antioxidant genes are not universally dysregulated in persister cells, persister cells consistently downregulate alternative ferroptosis suppressor FSP1 and rely upon residual FSP1 to survive GPX4 inhibition. These findings reveal new strategies to eliminate persister cells by combining GPX4 inhibitors with histone deacetylase or FSP1 inhibitors.

cancer biology↗

bioRxiv2025

Pharmacological potentiation of Nav1.1 channels in interneurons mitigates tau depositions and neuronal death in a mouse model of neurodegenerative dementias

Epileptiform discharges and neuronal hyperexcitability are key pathophysiological features of Alzheimers disease and related tauopathies. We previously identified selective dynfuntion of parvalbumin-positive GABAergic interneurons (PV neurons), which regulate neural network excitability, in a tauopathy mouse model. However, the mechanistic link between PV neuron deficits, tau pathology, and neurodegeneration remains unclear. Here, we demonstrate that pharmacological enhancement of phasic PV neuron activity markedly attenuates tau accumulation and neuronal loss in a tauopathy mouse model. We developed DSR-143630, a novel activator of voltage-gated sodium channel Nav1.1, selectively expressed in PV neurons. Administration of DSR-143630 alleviated febrile seizures in Nav1.1 haploinsufficient mice and suppressed high-frequency oscillations (HFOs), an electrophysiological signature of hyperexcitability associated with cognitive impairments, in rTg4510 tau transgenic mice. Longitudinal tau PET and volumetric MRI demonstrated that DSR-143630 treatment from 4 to 11 months of age profoundly reduced age-dependent tau deposition and atrophy in the neocortex and hippocampus. Postmortem analyses further revealed decreased levels of phosphorylated tau, preservation of neuronal populations, and attenuated neuroinflammatory responses, including reactive gliosis. These findings establish PV neuron dysfunctions and consequent network hyperexcitability as key drivers of tau pathogenesis and highlight pharmacological Nav1.1 activation as a promising disease-modifying strategy for neurodegenerative tauopathies. One Sentence SummaryPharmacological potentiation of interneuronal activities attenuates aberrant network excitability, progressive tau deposition, and neurodegeneration.

neuroscience↗

bioRxiv2025

Cortical α-synuclein pathology induces cell autonomous neuronal hypoactivity and compensatory circuit changes in a model of early Lewy Body Dementia

Posterior cortical impairments in visuospatial/perceptual function are common non-motor symptoms of the Lewy Body Dementias (LBD) and are relatively specific for LBDs compared to other dementias. Across populations, cognitive impairments correlate with the presence of -synuclein (-syn) pathology in limbic and neocortical brain regions. However, the specific role that -syn pathology plays in driving cortical circuit dysfunction and cognitive impairment remains controversial. We hypothesized that inducing -syn pathology in primary visual cortex (V1) in mice would impair neuronal activity and encoding of visual information, leading to visuoperceptual impairments. To test this, we injected -syn pre-formed fibrils (PFF) into V1, causing the formation of sparse Lewy-like pathology. Using longitudinal in vivo two-photon (2P) calcium imaging over 6 months, we recorded visually evoked activity of pyramidal cells in layer 2/3 (L2/3) and quantified -syn pathology using C05-05, a fluorescent ligand that binds aggregated -syn. Measuring population activity, we found a greater percentage of neurons in PFF-injected mice were responsive to visual stimuli with lower direction selectivity compared to controls at 4-5 months post-injection (MPI). Neurons with somatic Lewy-like inclusions showed reduced activity compared to neighboring neurons without inclusions. Conversely, neurons without somatic inclusions showed increased activity, positively correlated with the local burden of -syn pathology. Using a coherent motion discrimination task, we found no impairments in visuoperceptual ability in PFF-injected mice. Our results demonstrate that -syn pathology leads to reductions in neuronal activity in cells with somatic inclusions and reciprocal changes in local population activity but does not impair visuoperceptual function. Reflecting the early stages of neocortical -syn pathology, our model provides a framework for future studies to better understand the heterogeneity of cognitive symptoms and -syn pathology across patients.

neuroscience↗

bioRxiv2025

Remote Cortical Network for Frontal Cognitive Symptoms derived from Tau Accumulation in Progressive Supranuclear Palsy

Progressive Supranuclear Palsy (PSP) is a neurodegenerative disorder characterized by impaired movement and frontal cognitive dysfunctions. While motor symptoms have been linked with subcortical tau deposits, network mechanisms underlying the frontal cognitive symptoms remain unclear because pathological tau accumulation is quite limited within the frontal cortex and heterogeneously distributed primarily in the subcortical regions. Here, we combined tau-PET using a high-contrast probe we have recently developed with normative connectome to resolve this issue. Tau-deposition sites were connected to a common cortical network that could not be identified through similar analyses based on atrophy detected by structural MRI. This network was predominantly overlapped with canonical action-mode and frontoparietal networks, which jointly support adaptive and goal-directed behavior. Critically, while the degree of subcortical primary tau deposition correlated with motor symptoms, only the degree of connectivity from tau-deposition sites to the derived cortical network explained the frontal cognitive deficits of individual patients. These findings suggest a novel mechanism that frontal cognitive impairments, but not motor deficits, in PSP are derived from remote effects of tau deposits, independent of atrophy, through the convergent connectivity to the identified common cortical network.

neuroscience↗

bioRxiv2024

Longitudinal assessment of DREADD expression and efficacy in the monkey brain

Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) offer a powerful means for reversible control of neuronal activity through systemic administration of inert actuators. Because chemogenetic control relies on DREADD expression levels, understanding and quantifying the temporal dynamics of their expression is crucial for planning long-term experiments in monkeys. In this study, we longitudinally quantified in vivo DREADD expression in macaque monkeys using positron emission tomography with the DREADD-selective tracer [11C]deschloroclozapine (DCZ), complemented by functional studies. Twenty macaque monkeys were evaluated after being injected with adeno-associated virus vectors expressing the DREADDs hM4Di or hM3Dq, whose expression was quantified as changes in [11C]DCZ binding potential from baseline levels. Expression levels of both hM4Di and hM3Dq peaked around 60 days post-injection, remained stable for about 1.5 years, and declined gradually after two years. Significant chemogenetic control of neural activity and behavior persisted for about two years. The presence of protein tags significantly influenced expression levels, with co-expressed protein tags reducing overall expression levels. These findings provide valuable insights and guidelines for optimizing the use of DREADDs in long-term primate studies and potential therapeutic applications.

neuroscience↗

bioRxiv2024

Single MAPT knock-in mouse models of frontotemporal dementia for sharing with the neurodegenerative research community

We recently reported development of human MAPT knock-in mice that carry single or double pathogenic mutations of frontotemporal dementia. However, it takes more than 14 months for the line with the most aggressive phenotypes to exhibit tau pathology without forming high-order tau oligomers, along with concomitant abnormal behavior. We thus generated MAPT knock-in mice carrying triple mutations, among which the MAPTP301S;Int10+3;S320F line exhibited robust pathology starting earlier than 6 months. Tau accumulation took place mainly in the thalamus, hypothalamus, amygdala and entorhinal cortex, but less so in the hippocampus, leading to synaptic loss, atrophy and behavioral abnormalities. Crossbreeding MAPTP301S;Int10+3;S320F with App knock-in mice AppNL-G-F resulted in the manifestation of tau pathology in the hippocampus and cortex. These mutant mice will be valuable tools for understanding the mechanisms of frontotemporal dementia, Alzheimers disease and other tauopathies.

neuroscience↗

bioRxiv2024

A neuroimaging dataset during sequential color qualia similarity judgments with and without reports

Recent neuroscientific research has advanced our understanding of consciousness, yet the connection between specific qualitative aspects of consciousness, known as "qualia," and particular brain regions or networks remains elusive. Traditional methods that rely on verbal descriptions from participants pose challenges in neuroimaging studies. To address this, our group has introduced a novel "qualia structure" paradigm that leverages exhaustive, structural, and relational comparisons among qualia instead of verbal reports. In this study, we present the first fMRI dataset that captures relational similarity judgments among two out of nine color qualia per trial from 35 participants. This dataset also includes a "no-report" condition in half of the trials to assess the impact of overt reporting. Additionally, each participants color discriminability was evaluated with a hue test conducted outside the scanner. Our data offer valuable insights into the brain functions associated with color qualia and contribute to a deeper understanding of the neural foundations of consciousness.

neuroscience↗

bioRxiv2024

Organ specificity and commonality of epigenetic aging in low- and high-running capacity rats

BackgroundEpigenetic drift, which are gradual age-related changes in DNA methylation patterns, plays a significant role in aging and age-related diseases. However, the relationship between exercise, epigenetics, and aging and the molecular mechanisms underlying their interactions are poorly understood. The aim of this study was to investigate the relationship between cardiorespiratory fitness (CRF), epigenetic aging, and promoter methylation of individual genes across multiple organs in selectively bred low- and high-capacity runner (LCR and HCR) aged rats. MethodsIn this study, we performed reduced representation bisulfite sequencing (RRBS) on LCR and HCR aged rats, focusing on the hippocampus, heart, soleus muscle, and large intestine samples. We calculated various epigenetic indicators, including rat epigenetic clocks, global mean DNA methylation (GMM), mean methylation entropy (MME), and gene-specific promoter methylation. ResultsEpigenetic clocks, trained on available rat blood-derived RRBS data did not reflect differences in CRF between LCR and HCR rats across all four organs. However, we observed organ specific differences in GMM and MME between LCR and HCR rats. The direction of these differences was the opposite compared to the age-related changes in the rat blood suggesting that a high CRF may mitigate age-related epigenetic changes in an organ-specific manner. Notably the soleus muscle, exhibited the most pronounced differences in promoter methylation due to CRF. We also identified seven genes whose promoter methylation was consistently influenced by CRF in all four organs. Moreover, we found that age acceleration of the soleus muscle was significantly higher compared to the heart and the hippocampus, and significantly lower compared to the large intestine. Finally, we found that the age acceleration was not consistent across organs. ConclusionsOur data suggest that CRF associates with epigenetic aging in an organ-specific manner and regulates the promoter methylation of individual genes in an organ-specific and organ-common manner. Our findings provide important insights into the biology of aging and emphasize the need to validate rejuvenation strategies in the context of the organ-specific nature of epigenetic aging.

physiology↗

bioRxiv2024

TRPC6 is a mechanosensitive channel essential for ultrasound neuromodulation in mammalian brain

Ultrasound neuromodulation has become an innovative technology that enables non-invasive intervention in mammalian brain circuits with high spatiotemporal precision. Despite the expanding utility of ultrasound neuromodulation in the neuroscience research field and clinical applications, the molecular and cellular mechanisms by which ultrasound impacts neural activity in the brain are still largely unknown. Here, we report that transient receptor potential canonical 6 (TRPC6), a mechanosensitive non-selective cation channel, is essential for ultrasound neuromodulation of mammalian neurons in vitro and in vivo. We first demonstrated that ultrasound irradiation elicited rapid and robust Ca2+ transients mediated via extracellular Ca2+ influx in cultured mouse cortical and hippocampal neurons. Ultrasound-induced neuronal responses were massively diminished by blocking either the generation of action potential or synaptic transmission. Importantly, both pharmacological inhibition and genetic deficiency of TRPC6 almost completely abolished neuronal responses to ultrasound. Furthermore, we found that intracerebroventricular administration of a TRPC6 blocker significantly attenuated the population of neuronal firings in the cerebral cortex evoked by transcranial ultrasound irradiation in mice. Our findings indicate that TRPC6 is an indispensable molecule of ultrasound neuromodulation in the intact mammalian brains, providing fundamental understanding of biophysical molecular mechanisms of ultrasound neuromodulation as well as insight into its future feasibility in neuroscience and translational researches in humans.

neuroscience↗

bioRxiv2024

Metabolic resistance of Abeta3pE-42, epitope of the anti-Alzheimer therapeutic antibody, donanemab.

The amyloid {beta} peptide (A{beta}) starting with pyroglutamate (pE) at position 3 and ending at position 42 (A{beta}3pE-42) is a dominant species that accumulates in the Alzheimers disease (AD) brain. Consistently, a therapeutic antibody raised against this species, donanemab, has been shown to be effective in recent clinical trials. While the primary A{beta} species produced physiologically is A{beta}1-40/42, an explanation for how and why this physiological A{beta} is converted to the pathological form has remained elusive. The conversion of A{beta}1-42 to A{beta}3pE-42 is likely to take place after deposition of A{beta}1-42 given that A{beta}3pE-42 plaques arise significantly later than A{beta}1-42 deposition in the brains of single App knock-in and APP-transgenic mice. Here, we present experimental evidence that accounts for the aging-associated A{beta}3pE-42 deposition: [1] A{beta}3pE-42 is metabolically more stable than other A{beta}X-42 species; [2] Deficiency of neprilysin (NEP), the major A{beta}-degrading enzyme, induces a relatively selective deposition of A{beta}3pE-42 in APP-Tg mice. [3] A{beta}3pE-42 deposition always colocalizes with cored plaques in both APP-Tg and App knock-in mouse brains; [4] A{beta}3E-42, an immediate precursor of A{beta}3pE-42, as well as A{beta}2A-42 and A{beta}4F-42 are more short-lived than A{beta}1-42 in vivo, indicating that simple N-terminal truncation that can arise enzymatically or spontaneously makes A{beta}X-42 easier to catabolize. Consistently, newly generated knock-in mice, AppNL-({Delta}DA)-F and AppNL-({Delta}DA)-Q-F, showed no detectable A{beta} pathology even after aging, indicating that the A{beta}3E-42 and A{beta}3Q-42 species are extremely labile to the in vivo catabolic system and that the E/Q cyclase activity present in mouse brain is insufficient for A{beta}3pE-42 generation. In addition, a deficiency of NEP facilitated A{beta}3pE-42 deposition. Of note, we identified a trace amount of A{beta}3pE-42 and its immediate precursor, A{beta}3E-42, in the insoluble fraction of NEP-deficient APP-Tg mouse brains. A{beta}3pE-42 is thus likely to be a probabilistic by-product of A{beta}1-42 metabolism that selectively accumulates over a long-time range of brain aging. It is likely produced in the solid state or at the solid-liquid interface. Our findings suggest that anti-A{beta} therapies will probably be most effective if given before A{beta}3pE-42 deposition takes place.

neuroscience↗

bioRxiv2023

Distinct roles of monkey OFC-subcortical pathways in adaptive behavior

To be the most successful, primates must adapt to changing environments and optimize their behavior by making the most beneficial choices. At the core of adaptive behavior is the orbitofrontal cortex (OFC) of the brain, which updates choice value through direct experience or knowledge-based inference. Here, we identify distinct neural circuitry underlying these two separate abilities. We designed two behavioral tasks in which macaque monkeys updated the values of certain items, either by directly experiencing changes in stimulus-reward associations, or by inferring the value of unexperienced items based on the tasks rules. Chemogenetic silencing of bilateral OFC combined with mathematical model-fitting analysis revealed that monkey OFC is involved in updating item value based on both experience and inference. In vivo imaging of chemogenetic receptors by positron emission tomography allowed us to map projections from the OFC to the rostromedial caudate nucleus (rmCD) and the medial part of the mediodorsal thalamus (MDm). Chemogenetic silencing of the OFC-rmCD pathway impaired experience-based value updating, while silencing the OFC-MDm pathway impaired inference-based value updating. Our results thus demonstrate a dissociable contribution of distinct OFC projections to different behavioral strategies, and provide new insights into the neural basis of value-based adaptive decision-making in primates.

neuroscience↗

bioRxiv2023

Multimodal imaging for validation and optimization of ion channel-based chemogenetics in nonhuman primates

Chemogenetic tools provide an opportunity to manipulate neuronal activity and behavior selectively and repeatedly in nonhuman primates (NHPs) with minimal invasiveness. Designer Receptors Exclusively Activated by Designer Drugs are one example that is based on mutated muscarinic acetylcholine receptors. Another channel-based chemogenetic system available for neuronal modulation in NHPs uses Pharmacologically Selective Actuator Modules (PSAMs), which are selectively activated by Pharmacologically Selective Effector Molecules (PSEMs). To facilitate the use of the PSAM/PSEM system, the selection and dosage of PSEMs should be validated and optimized for NHPs. To this end, we used a multimodal imaging approach. We virally expressed excitatory PSAM (PSAM4-5HT3) in the striatum and the primary motor cortex of two macaque monkeys, and visualized its location through positron emission tomography (PET) with the reporter ligand [18F]ASEM. Chemogenetic excitability of neurons triggered by two PSEMs (uPSEM817 and uPSEM792) was evaluated using [18F]fluorodeoxyglucose-PET imaging, with uPSEM817 being more efficient than uPSEM792. Pharmacological magnetic resonance imaging showed that increased brain activity in the PSAM4-expressing region began approximately 13 min after uPSEM817 administration and continued for at least 60 min. Our multimodal imaging data provide valuable information regarding the manipulation of neuronal activity using the PSAM/PSEM system in NHPs, facilitating future applications. Significance statementLike other chemogenetic tools, the ion channel-based system called Pharmacologically Selective Actuator Module/Pharmacologically Selective Effector Molecule (PSAM/PSEM) allows remote manipulation of neuronal activity and behavior in living animals. Nevertheless, its application in non-human primates (NHPs) is still limited. Here, we used multi-tracer positron emission tomography (PET) imaging and pharmacological magnetic resonance imaging (MRI) to visualize an excitatory chemogenetic ion channel (PSAM4-5HT3) and validate its chemometric function in macaque monkeys. Our results provide the optimal agonist, dose, and timing for chemogenetic neuronal manipulation, facilitating the use of the PSAM/PSEM system and expanding the flexibility and reliability of circuit manipulation in NHPs in a variety of situations.

neuroscience↗

bioRxiv2023

Unsupervised decomposition and description of nonhuman primate behavior

Nonhuman primates (NHPs) exhibit complex and diverse behavior that typifies advanced cognitive function and social communication, but quantitative and systematical measure of this natural nonverbal processing has been a technical challenge. Specifically, a method is required to automatically segment time series of behavior into elemental motion motifs, much like finding meaningful words in character strings. Here, we propose a solution called SyntacticMotionParser (SMP), a general-purpose unsupervised behavior parsing algorithm using a non-parametric Bayesian model. Using three-dimensional posture-tracking data from NHPs, SMP automatically outputs an optimized sequence of latent motion motifs classified into the most likely number of states. When applied to behavioral datasets from common marmosets and rhesus monkeys, SMP outperformed conventional posture-clustering models and detected a set of behavioral ethograms from publicly available data. SMP also quantified and visualized the behavioral effects of chemogenetic neural manipulations. SMP thus has the potential to dramatically improve our understanding of natural NHP behavior in a variety of contexts.

neuroscience↗

bioRxiv2023

Reduced serotonergic transmission alters sensitivity to cost and reward via 5-HT1A and 5-HT1B receptors in monkeys

Deficiency of the serotonin (5-HT) system is considered one of the core biological pathologies of depression and other psychiatric disorders whose key symptom is decreased motivation. Yet, the exact role of 5-HT in motivation remains controversial and elusive. Here, we pharmacologically manipulated the 5-HT system and quantified effects on motivation in terms of incentives and costs for goal-directed action in monkeys. Reversible inhibition of 5-HT synthesis increased refusal responses and reaction times in goal-directed task performance, indicating decreased motivation that could be separated into value-dependent and -independent components. To identify the receptor subtypes involved in these components, we systemically administered antagonists specific for four major 5-HT receptor subtypes: 5-HT1A, 5-HT1B, 5-HT2A, and 5-HT4. Positron emission tomography visualized the unique distribution of each subtype in limbic brain regions and determined the systemic antagonist dose that achieved approximately 30% occupancy. We found that blockade of 5-HT1A, but not other receptor subtypes, increased sensitivity to future workload and time-delay to reward, and decreased motivation in a value-independent manner. Moreover, blocking only 5-HT1B receptors reduced the impact of incentive value on motivation. These results suggest that two distinct processes, mediated by 5-HT1A and 5-HT1B receptors, lead to reduced motivation in 5-HT system deficiency.

neuroscience↗

bioRxiv2023

Physicochemical properties of the vacuolar membrane and cellular factors determine formation of vacuolar invaginations

Vacuoles change their morphology in response to stress. In yeast exposed to chronically high temperatures, vacuolar membranes get deformed and invaginations are formed. We show that phase-separation of vacuolar membrane occurred after heat stress leading to the formation of the invagination. In addition, Hfl1, a vacuolar membrane-localized Atg8-binding protein, was found to suppress the excess vacuolar invaginations after heat stress. At that time, Hfl1 formed foci at the neck of the invaginations in wild-type cells, whereas it was efficiently degraded in the vacuole in the atg8{Delta} mutant. Genetic analysis showed that the endosomal sorting complex required for transport (ESCRT) machinery was necessary to form the invaginations irrespective of Atg8 or Hfl1. In contrast, a combined mutation with the vacuole BAR domain protein Ivy1 led to vacuoles in hfl1{Delta}ivy1{Delta} and atg8{Delta}ivy1{Delta} mutants having constitutively invaginated structures; moreover, these mutants showed stress-sensitive phenotypes. Our findings suggest that vacuolar invaginations result from the combination of changes in the physiochemical properties of the vacuolar membrane and other cellular factors. Summary statementVacuolar invaginations occur through a combination of the changes of physiochemical properties of the vacuolar membrane and other cellular factors in yeast. Particularly, Hfl1 suppresses the excess invaginations.

cell biology↗

bioRxiv2022

Distribution of intraperitoneally administered D2O in AQP4-knockout mouse brain after MCA occlusion

As the movement of water in the brain is known to be involved in neural activity and various brain pathologies, the ability to assess water dynamics in the brain will be important for the understanding of brain function and the diagnosis and treatment of brain diseases. Aquaporin-4 (AQP4) is a membrane channel protein that is highly expressed in brain astrocytes and is important for the movement of water molecules in the brain. In this study, we investigated the contribution of AQP4 to brain water dynamics by administering deuterium-labeled water (D2O) intraperitoneally to wild-type and AQP4 knockout (AQP4-ko) mice that had undergone surgical occlusion of the middle cerebral artery. Water dynamics in the infarct region and on either side of the anterior cerebral artery (ACA) was monitored with proton-density-weighted imaging (PDWI) performed on a 7T animal MRI. D2O caused a negative signal change quickly after administration. The AQP4-ko mice showed a delay of the time-to-minimum in both contralateral and ipsilateral ACA region compared to wild-type mice. Also, only the AQP4-ko mice showed a delay of the time-to-minimum in the ipsilateral ACA region compared to the contralateral side. In only the wild-type mice, the signal minimum in the ipsilateral ACA region was higher than that in the contralateral ACA region. In the infarct region, the signal attenuation was slower for the AQP4-ko mice in comparison to the wild-type mice. These results suggest that AQP4 loss affects water dynamics in the ACA region not only in the infarct region. Dynamic PDWI after D2O administration may be a useful tool for showing the effects of AQP4 in vivo. HighlightsO_LIThe measurement of brain water dynamics with D2O. C_LIO_LIIn vivo investigation of AQP4 loss and focal brain ischemia. C_LIO_LIAQP4 loss affects water dynamics in the ACA region not only in the infarct region. C_LI

physiology↗