Biology subjects

Miyazaki, M.

Publications and source records attributed to Miyazaki, M..

At least 19 recordsLinked to original sources

bioRxiv2026

High-fat diet-induced obesity differentially alters circadian gene expression across peripheral tissues

Circadian rhythms regulate diverse physiological processes, including metabolism, and their disruption has been implicated in metabolic disorders such as obesity. However, the tissue-specific effects of obesity on peripheral circadian clocks remain incompletely understood. Here, we investigated the impact of high-fat diet (HFD)-induced obesity on circadian gene expression in skeletal muscle, liver, and white adipose tissue (WAT). Mice were fed either a regular diet (RD) or HFD for 6 weeks, followed by tissue collection at 4-hour intervals over a 24-hour period. Under RD conditions, key circadian regulators and their downstream targets exhibited robust 24-hour oscillations across all tissues. In contrast, HFD feeding induced distinct, tissue-specific alterations. In the liver, Per2, Dbp, and Rev-erb showed phase-advanced expression patterns, whereas in WAT, rhythmic expression was markedly attenuated. Notably, skeletal muscle largely preserved circadian gene expression patterns, indicating relative resistance to HFD-induced circadian disruption. In addition, HFD feeding altered metabolic gene expression in adipose tissue, characterized by reduced Pgc1 expression and increased Leptin expression. Together, these findings demonstrate that HFD-induced obesity differentially disrupts peripheral circadian clocks in a tissue-specific manner and highlight skeletal muscle as a relatively resilient tissue. These results provide insight into how circadian dysregulation contributes to metabolic abnormalities in obesity.

physiology↗

bioRxiv2026

High-resolution spatial profiling identifies disease-specific molecular architecture in palmoplantar pustulosis

Palmoplantar pustulosis (PPP) and dyshidrotic eczema (DE) are chronic vesiculopustular dermatoses with overlapping clinical presentations but distinct underlying biology. Although comparative transcriptomic and proteomic analyses between PPP and DE have been reported, they remain limited in number and scope, with no comprehensive understanding of their distinct molecular signatures. Moreover, their molecular mechanisms remain unclear, and currently available therapeutic options are limited. To clarify disease-specific epidermal programs underlying vesicle formation, we conducted Visium HD spatial transcriptomic analysis of FFPE lesional skin samples obtained from patients with PPP and DE, followed by immunohistochemical validation against normal palmoplantar skin controls. Spatial clustering identified a keratinocyte subpopulation adjacent to vesicles that exhibited distinct transcriptional programs in the two diseases. In PPP, vesicle-associated keratinocytes demonstrated marked downregulation of aquaporin-3 (AQP3) and E-cadherin, together with strong, spatially localized activation of JAK-STAT3 signaling. Conversely, DE exhibited diffuse AQP3 expression and more homogeneous activation of JAK-STAT3 signaling throughout the epidermis. These results indicate that, although PPP and DE share inflammatory pathways, they differ substantially in their spatial molecular architecture. Reduced AQP3 expression and localized STAT3 activation may contribute to vesicle formation in PPP, supporting our previous hypothesis that implicates intraepidermal sweat leakage as a pathogenic mechanism in PPP. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=130 SRC="FIGDIR/small/723901v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@72a341org.highwire.dtl.DTLVardef@3c0beaorg.highwire.dtl.DTLVardef@325098org.highwire.dtl.DTLVardef@1493ebf_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2026

TMEM174 Deficiency Reduces Longevity by Promoting Phosphate-Driven Vascular Calcification

BackgroundDysregulation of phosphate homeostasis contributes to reduced longevity and vascular complications in chronic kidney disease and aging. This study investigates the role of TMEM174, a proximal tubule-specific protein, in regulating the phosphate co-transporter NPT2A and its subsequent impact on lifespan and vascular health. MethodsTMEM174 knockout (KO) mice (C57BL6/J and DBA/2J) were fed diets with varying phosphate concentrations (0.6% vs. 1.2%). In OKP cells, TIRF and FRET microscopy, alongside immunoprecipitation, were used to identify the TMEM174 protein regions essential for NPT2A binding and endocytosis. ResultsTMEM174 KO mice exhibited significantly shorter lifespans than wild-type controls. High phosphate diets exacerbated vascular calcification, stiffness, and mortality, while low phosphate diets rescued these phenotypes. In vitro, TMEM174 siRNA blocked PTH-induced NPT2A endocytosis, increasing its apical membrane retention. FRET and biochemical assays revealed that the C-terminal region of TMEM174 is essential for its association with NPT2A. While intact TMEM174 and N-terminal mutants (TMEM174{Delta}N) facilitated NPT2A degradation, C-terminal deletions (TMEM174{Delta}C) failed to associate with or degrade NPT2A. ConclusionsTMEM174 is a critical regulator of phosphate homeostasis and longevity. The C-terminal region of TMEM174 is specifically required for NPT2A endocytosis and degradation, identifying it as a potential therapeutic target for managing phosphate-related vascular complications.

physiology↗

bioRxiv2025

A dual-domain chitinase mechanism enables marine bacteria tosense and localize sparse crystalline chitin in the ocean

Chitin is one of the most abundant biopolymers in the ocean, and its remineralisation underpins major pathways of marine carbon cycling. A central challenge for chitinolytic bacteria is to locate and remain associated with sparsely distributed crystalline chitin particles. Here, we show that the GH18 chitinase VpChi1 from Vibrio parahaemolyticus possesses a dual-domain architecture that enhances particle encounter and retention. Full-length VpChi1 displayed much higher catalytic efficiency than a CBD-truncated mutant at low chitin concentrations, whereas substrate inhibition occurred at higher concentrations. Single-molecule fluorescence imaging demonstrated that the additional C-terminal chitin-binding domain (CBD) enables selective binding to the hydrophobic surface of crystalline chitin and substantially prolongs enzyme residence time. Kinetic simulations using experimentally determined dissociation rates showed that this extended residence arises from CBD-assisted rebinding of the catalytic domain. High-speed atomic force microscopy confirmed that the CBD does not alter stepping velocity or travel distance along individual crystals, indicating that substrate inhibition likely results from CBD engagement with neighbouring particles rather than impaired motility. Screening of seawater and marine sediments across multiple depths identified Vibrio and Pseudoalteromonas species as dominant chitin degraders, many encoding GH18 chitinases with dual CBDs, whereas terrestrial bacteria generally lacked this architecture. We propose that this two-domain configuration confers an ecological advantage by increasing enzyme retention on particulate chitin and enabling sustained production of chitobiose, a potent chemotactic signal for marine bacteria. These findings reveal a mechanistic basis for how bacteria sense and exploit particulate chitin and highlight an adaptive strategy for resource acquisition in the ocean.

molecular biology↗

bioRxiv2025

Kidney-specific lipid metabolism underlies stable chemical individuality in domestic cats and other felids

Domestic cats uniquely accumulate lipid droplets (LDs) in renal proximal tubular epithelial cells, but their chemical composition and biological functions remain unknown. Here, we identify a distinctive renal specialization in felids: lipid droplets enriched in branched-chain fatty acids (BFAs). These BFAs accumulate as triglyceride components and are excreted in urine as free fatty acids with stable and individually distinctive profiles. Behavioral assays show that cats discriminate urine samples based on BFA composition, even against complex volatile backgrounds, suggesting BFAs as robust, metabolically encoded olfactory signatures for individual recognition. Comparative analyses of non-domesticated felids reveal that BFA production is broadly conserved but exhibits both species-specific and individual variation. These findings demonstrate how a core metabolic pathway has been evolutionarily co-opted into a chemical signature system. This discovery highlights an unusual integration of renal physiology with social communication and expand our understanding of lipid metabolism, organ-level adaptation, and the evolution of chemical individuality in mammals. Significance statementUnique lipid droplets in felid kidneys reveal how organ-specific metabolism can be adapted for social communication.

zoology↗

bioRxiv2025

Kinetic scheme of myosin phosphorylation by ZIP kinase

Zipper-interacting protein kinase (ZIPK) is a ubiquitous serine/threonine protein kinase that plays pivotal roles in regulating cell motility, division, and smooth muscle contractility through phosphorylation of myosin. In this study, we systematically investigated the phosphorylation reactions of smooth muscle myosin (SMM) by ZIPK. We found that ZIPK phosphorylates MRLC sequentially, first at Ser19 and then at Thr18, determined by quantitative mass spectrometry analysis on wild-type MRLC. Analysis on phosphomimic and unphosphorylatable MRLC mutants indicates that the phosphorylation rate at Ser19 on unphosphorylated MRLC is 1.5 times faster than that at Thr18 on Ser19-phosphorylated MRLC. Comparison between SMM and isolated MRLC revealed that the phosphorylation rate of SMM is slower than that of isolated MRLC. To dissect the molecular mechanism responsible for this difference, we measured interactions between ZIPK and SMM by co-sedimentation assay. The result suggests that the C-terminal domain of ZIPK interacts with the heavy chain of SMM, and as a result, competitive binding of ZIPK to MRLC and the myosin heavy chain suppresses phosphorylation of SMM compared to isolated MRLC. By incorporating the kinetic and dissociation constants obtained from mutant analysis and co-sedimentation assays, respectively, a simple kinetic model accurately reproduced the time courses of phosphorylation for both isolated MRLC and SMM. This provides systemic insight into the regulatory mechanism of myosin contractility by ZIPK.

biochemistry↗

bioRxiv2025

Lipid composition effects on the number and size of liposomes formed by the inverted emulsion method

Liposomes have been widely employed as membrane scaffolds in the construction of minimal cell models. In 2002, the inverted emulsion method was introduced as a novel technique for generating giant liposomes by transferring water-in-oil droplets across an oil/water interface. This technique enables the encapsulation of purified proteins or cytoplasmic extracts into cell-sized liposomes under physiological buffer conditions, and has since become a cornerstone in bottom-up synthetic biology. Despite its broad application over the past two decades, the effects of lipid composition on the production yield and size distribution of liposomes generated by the inverted emulsion method remain largely unknown. In this study, we systematically investigated the effects of phospholipid composition on the production yield and size distribution of liposomes generated using the inverted emulsion method. We used a natural phosphatidylcholine purified from chicken egg yolk (egg PC) as the base membrane component, and examined the extent to which substituting a fraction of egg PC with other phospholipids--differing in net electric charge and/or the molecular weight of their hydrophilic head groups--affects the number and size distribution of liposomes. We found that a 10% replacement of egg PC with charged phospholipids significantly enhances the production yield of liposomes by approximately tenfold, transformed by both the natural gravitational force and the greater force applied by centrifugation. In addition, lipids with smaller head groups slightly enhance the production yield in both methods. Lipids with larger head groups also slightly enhance the production yield and promote the formation of larger liposomes in the natural sedimentation method, but these effects are diminished in the centrifugal sedimentation method, presumably due to the strong centrifugal force. These findings provide valuable guidelines for optimizing preparation protocols for minimal cell models.

biophysics↗

bioRxiv2025

Cold-induced suppression of myogenesis in skeletal muscle stem cells contributes to delayed muscle regeneration during hibernation

Mammalian hibernators experience profound cold stress and prolonged physical inactivity during torpor periods; however, it is unclear how skeletal muscle stem cells (satellite cells; SCs) respond to these challenges. In this study, we demonstrate that SCs from a mammalian hibernator, Syrian hamster exhibit remarkable resistance to cold-induced cell death, which is associated with intrinsically higher expression of the antioxidant enzyme GPX4, which likely contributes to the suppression of ferroptosis. RNA-seq analysis revealed widespread downregulation of myogenesis-related genes following cold exposure, which suggests suppression of the myogenic program. Consistently, SCs exposed to cold stress exhibited reduced activation and differentiation capacities upon subsequent rewarming, with an increased number of quiescent Pax7-positive/MyoD-negative cells. Muscle regeneration was markedly delayed during hibernation, accompanied by decreased SC activation and macrophage infiltration, suggesting that cold-induced suppression of SC function underlies limited regenerative capacity in hibernating hamsters. Our results provide insight into the unique physiology of mammalian hibernators: SC viability is preserved, whereas regenerative activity is selectively suppressed during hibernation.

physiology↗

bioRxiv2025

Reconstitution of actomyosin networks in cell-sized liposomes reveals distinct mechanical roles of cytoskeletal organization in membrane shape remodeling

The actin cortex, a thin layer of actomyosin network beneath the plasma membrane, regulates various cell functions by generating active forces and inducing membrane deformations, including blebs. Although upstream signaling is involved in regulating cell shape, the extent to which downstream actomyosin molecules can control the shape remains elusive. Here, using a minimal reconstituted system with a combination of agent-based computational model, we show that while actin-membrane coupling strength determines the magnitude of membrane deformation, its balance with actin network connectivity governs the bleb initiation mechanism, either by detachment of the cortex from the membrane or by rupture of the cortex. This balance also regulates whether single or multiple blebs form. Furthermore, both experiments and simulations suggest that not only the dense cortical network but also the sparse volume-spanning network actively contributes to regulating bleb number. These findings provide mechanical insights into how cells tune actin network organization to control their shape.

biophysics↗

bioRxiv2025

Eukaryotes' closest relatives are internally simple syntrophic archaea

Eukaryotes are theorized to have originated from an archaeal phylum Promethearchaeota (formerly Asgard archaea)1,2. The first cultured representatives revealed valuable insight3,4 but are distantly related to the first eukaryotic common ancestor (FECA), leaving many unknowns regarding this archaeons biology. Here, we report isolation of two strains belonging to the order proposed as FECAs closest relative, Hodarchaeales,5 as members of a pure co- and tri-culture with methanogenic partners. Both are obligately anaerobic, syntrophic, peptide-degrading, and mesophilic archaea that have simple internal cell structure and produce protrusions and vesicles, like Promethearchaeales3,4. All strains demonstrate behavior focused on cell construction rather than division, unlike typical prokaryotes6. Strain HC1 possesses genes associated with aerobic lifestyles but lacks complete pathways for aerobic respiration and co-cultures cannot grow under (micro)aerobic conditions, suggesting the genes support oxygen detoxification rather than respiration. Reflecting this, HC1 can survive and grow under microaerobic conditions only when aerobic organisms are present. Phylogenetic analyses indicate FECA may have possessed these genes and thus some aerotolerance. Physiological, genomic, and phylogenetic observations indicate FECA was a simple-celled anaerobic syntrophic peptide-degrading archaeon with a non-growth-centric lifestyle and potential adaptations towards an oxygenated planet--the archaea-eukaryote transition was steep in both cell structure and aerobiosis.

microbiology↗

bioRxiv2024

Optogenetic actin network assembly on lipid bilayer uncovers the network density-dependent functions of actin-binding proteins

The actin cytoskeleton forms a mesh-like network that drives cellular deformations. The network property is defined by the network density and the species of actin-binding proteins. However, the relationship between the network density, the penetration ability of actin-binding proteins into the network, and resulting network dynamics remains elusive. Here, we report an in vitro optogenetic system, named OptoVCA, which induces Arp2/3 complex-mediated actin network assembly on a lipid membrane. By changing the illumination power, duration, and pattern, the OptoVCA flexibly manipulates the density, thickness, and shape of the actin network. Taking these advantages, we examine the effects of the network density on two representative actin-binding proteins, myosin and ADF/cofilin. We find that the penetration of myosin filaments into the network is strictly inhibited by only a several-fold increase in network density due to the steric hindrance. Furthermore, penetrated myosin filaments induce directional actin flow when the network has a density gradient. On the other hand, ADF/cofilin penetrates into the network regardless of network density. However, network disassembly is dramatically inhibited by only a several-fold increase in network density. Thus, the OptoVCA contributes to understanding cell mechanics by examining the network density-dependent effects on actin-binding proteins.

cell biology↗

bioRxiv2024

Chimeras of Kinesin-6 and Kinesin-14 reveal head-neck-tail domain functions and dysfunctions that lead to aneuploidy in fission yeast

Kinesin motors play diverse roles in cells, including spindle assembly and chromosome segregation. Each kinesin has three general domains - the motor head, neck, and tail. As microtubule (MT) motors, kinesins have directionality, walking toward the plus- or minus-end of a MT. Plus-end kinesins have their motor head at the N-terminus, while minus-end kinesins have their motor head at the C-terminus. Interestingly, in vitro data indicate that the motor head does not dictate directionality. Here, we seek to understand the cellular function of each kinesin domain. We systematically created chimeras of fission yeast kinesin-6 Klp9 (a plus-end kinesin localized at the spindle midzone to slide the MTs and elongate the spindle) and kinesin-14 Pkl1 (a minus-end kinesin localized at the spindle poles to focus MTs). Our in vivo data reveal that the tail dictates cellular localization, and in some cases directionality of the motor head; the motor head produces binding and sliding forces affecting spindle function; and the neck modulates the forces of the motor head. Specifically, Pkl1-head, when put on Klp9-neck-tail, walks toward the spindle midzone and slides MTs faster than the wild-type Klp9. This results in spindle breakage and aneuploidy. In contrast, Klp9-head, when put on Pkl1-neck-tail, localizes to the spindle poles, but failed to properly focus MTs, leading to abnormal MT protrusions. This results in asymmetric displacement of the chromosomes and aneuploidy. Our studies reveal domain-dependent control of motor localization, direction, and force production, whose dysfunctions lead to different modes of aneuploidy.

cell biology↗

bioRxiv2024

Protein design of two-component tubular assemblies like cytoskeletons

Recent advances in protein design have ushered in an era of constructing intricate higher-order structures1. Despite this progress, orchestrating the assembly of diverse protein units into cohesive artificial structures akin to biological assembly systems, especially in tubular forms, remains an elusive goal. To address this, we introduce the Nature-Inspired Protein Assembly Design (NIPAD), a novel methodology that utilises two distinct protein units to create unique tubular structures under carefully designed conditions. These structures demonstrate dynamic flexibility similar to that of actin filaments, with cryo-electron microscopy revealing diverse morphologies, like microtubules. By mimicking actin filaments, helical conformations were incorporated into tubular assemblies, thereby enriching their structural diversity. Remarkably, these assemblies can be reversibly disassembled and reassembled in response to environmental stimuli, such as changes in salt concentration and temperature, mirroring the dynamic behaviour of natural systems. NIPAD combines rational protein design with biophysical insights, leading to the creation of biomimetic, adaptable, and reversible higher-order assemblies. This approach deepens our understanding of protein assembly design and complex biological structures. Concurrently, it broadens the horizons of synthetic biology and material science, holding significant implications for unravelling lifes fundamental processes and pioneering new applications.

biochemistry↗

bioRxiv2024

The ER-phagy receptor FAM134B is targeted by Salmonella Typhimurium to promote infection

Macroautophagy/autophagy is a key catabolic-recycling pathway that can selectively target damaged organelles or invading pathogens for degradation. The selective autophagic degradation of the endoplasmic reticulum (hereafter referred to as ER-phagy) is a homeostatic mechanism, controlling ER size, the removal of misfolded protein aggregates, and organelle damage. ER-phagy is also stimulated by pathogen infection. However, the link between ER-phagy and bacterial infection remains poorly understood, as are the mechanisms evolved by pathogens to escape the effects of ER-phagy. Here, we show that Salmonella enterica serovar Typhimurium inhibits ER-phagy by targeting the ER-phagy receptor FAM134B, leading to a pronounced increase in Salmonella viability after invasion. Salmonella prevents FAM134B oligomerization, which is required for efficient ER-phagy. FAM134B knock-out raises intracellular Salmonella number, while FAM134B activation reduces Salmonella burden. Additionally, we found that Salmonella targets FAM134B through the bacterial effector SopF to enhance intracellular survival through ER-phagy inhibition. Furthermore, FAM134B knock-out mice infected with Salmonella presented severe intestinal damage and increased bacterial burden. These results provide new mechanistic insight into the interplay between ER-phagy and bacterial infection, highlighting a key role for FAM134B in innate immunity.

molecular biology↗

bioRxiv2023

Body-part specificity for learning of multiple prior distributions in human coincidence timing

During timing tasks, the brain learns the statistical distribution of target intervals and integrates this prior knowledge with sensory inputs to optimise task performance. Daily events can have different temporal statistics (e.g. fastball/slowball in baseball batting), making it important to learn and retain multiple priors. However, the rules governing this process are not yet understood. Here, we demonstrate that the learning of multiple prior distributions in a coincidence timing task is characterised by body-part specificity. In our experiments, two prior distributions (short and long intervals) were imposed on participants. When using only one body part for timing responses, regardless of the priors, participants learned a single prior by generalising over the two distributions. However, when the two priors were assigned to different body parts, participants concurrently learned the two independent priors. Moreover, body-part specific prior acquisition was faster when the priors were assigned to anatomically distant body parts (e.g. hand/foot) than when they were assigned to close body parts (e.g. index/middle fingers). This suggests that the body-part specific learning of priors is organised according to somatotopy.

neuroscience↗

bioRxiv2023

Activation of the IKK2-NFκB pathway in VSMCs inhibits calcified vascular stiffness in CKD by reducing the secretion of calcifying extracellular vesicles.

IKK2-NF{kappa}B pathway mediated-inflammation in vascular smooth muscle cells (VSMCs) has been proposed to be an etiologic factor in medial calcification and stiffness. However, the role of the IKK2-NF{kappa}B pathway in medial calcification remains to be elucidated. In this study, we found that CKD induces inflammatory pathways through the local activation of the IKK2-NF{kappa}B pathway in VMSCs associated with calcified vascular stiffness. Despite reducing the expression of inflammatory mediators, complete inhibition of the IKK2-NF{kappa}B pathway in vitro and in vivo unexpectedly exacerbated vascular mineralization and stiffness. In contrast, activation of NF{kappa}B by SMC-specific I{kappa}B deficiency attenuated calcified vascular stiffness in CKD. Inhibition of the IKK2-NF{kappa}B pathway induced apoptosis of VSMCs by reducing anti-apoptotic gene expression, whereas activation of NF{kappa}B reduced CKD-dependent vascular cell death. In addition, increased calcifying extracellular vesicles through the inhibition of the IKK2-NF{kappa}B pathway induced mineralization of VSMCs, which was significantly reduced by blocking cell death. This study reveals that activation of the IKK2-NF{kappa}B pathway in VSMCs plays a protective role in CKD-dependent calcified vascular stiffness by reducing the release of apoptotic calcifying extracellular vesicles.

physiology↗

bioRxiv2022

Liver type 1 innate lymphoid cells lacking IL-7 receptor are a native killer cell subset fostered by parenchymal niches

Group 1 innate lymphoid cells (G1-ILCs), including circulating natural killer (NK) cells and tissue-resident type 1 ILCs (ILC1s), are innate immune sentinels critical for responses against infection and cancer. In contrast to relatively uniform NK cells through the body, diverse ILC1 subsets have been characterized across and within tissues in mice, but their developmental and functional heterogeneity remain unsolved. Here, using multimodal in vivo approaches including fate-mapping and targeting of the interleukin 15 (IL-15)-producing microenvironment, we demonstrate that liver parenchymal niches support the development of a cytotoxic ILC1 subset lacking IL-7 receptor (7R- ILC1s). During ontogeny, fetal liver (FL) G1-ILCs arise perivascularly and then differentiate into 7R- ILC1s within sinusoids. Hepatocyte-derived IL-15 supports parenchymal development of FL G1-ILCs to maintain adult pool of 7R- ILC1s. IL-7R+ (7R+) ILC1s in the liver, candidate precursors for 7R- ILC1s, are not essential for 7R- ILC1 development in physiological conditions. Functionally, 7R- ILC1s exhibit killing activity at steady state through granzyme B expression, which is underpinned by constitutive mTOR activity, unlike NK cells with exogenous stimulation-dependent cytotoxicity. Our study reveals the unique ontogeny and functions of liver-specific ILC1s, providing a detailed interpretation of ILC1 heterogeneity.

immunology↗

bioRxiv2022

Decline of intrinsic cerebrospinal fluid outflow in healthy humans with age detected by non-contrast spin-labeling MRI

BackgroundClearance of cerebrospinal fluid (CSF) is important for the removal of toxins from the brain, with implication for neurodegenerative diseases. Imaging evaluation of CSF outflow in humans has been limited, relying on injections of contrast agents. Objective of this study was to introduce a novel spin-labeling magnetic resonance imaging (MRI) technique to detect and quantify the movement of endogenously tagged CSF without administration of tracer or contrast media, and use the technique to evaluate CSF outflow in normal human subjects with varying ages. MethodsThis study was performed on a clinical 3-Tesla MRI scanner in healthy subjects (10 males and 6 females; mean age, 47.6 {+/-} 18.9 years; range, 19-71 years) with informed consent. Our non-contrast spin-labeling MRI technique applies a tag pulse on the brain hemisphere, including subarachnoid space, dura mater, brain parenchyma, and images the outflow of the tagged CSF into the superior sagittal sinus. We obtained 3-dimensional images in real time, which was analyzed to determine tagged-signal changes in different regions of the brain involved in CSF outflow or clearance. Additionally, the signal changes over time were fit to a signal curve to determine quantitative flow metrics such as relative CSF flow and volume. These were correlated against subject age to determine aging effects. ResultsWe observed the signal of the tagged CSF moving from the subarachnoid space to the dura mater and parasagittal dura, and finally draining into the superior sagittal sinus. In addition, there was strong evidence of a direct pathway by which tagged CSF flows directly from the subarachnoid space to the superior sagittal sinus, via the lateral wall of superior sagittal sinus. Furthermore, quantitative CSF outflow metrics were shown to decrease significantly with age. ConclusionsWe demonstrated a novel non-invasive MRI technique to evaluate CSF clearance in humans. In this study, we identified possible two CSF clearance pathways, and determined normative values and decline of CSF flow metrics in normal ages. Our work provides a new opportunity to better understand the relationships of these CSF clearance pathways in ages, which may be a significant factor in the age-related prevalence of neurodegenerative diseases. FundingThis study was supported by the National Institutes of Health grants: RF1AG076692 (MM) and R01HL154092 (MM); and made possible by a grant from Canon Medical Systems. Corp., Japan. Clinical trialNot applicable.

neuroscience↗