Biology subjects

Sugita, S.

Publications and source records attributed to Sugita, S..

12 recordsLinked to original sources

bioRxiv2026

Sex Differences in Aortic Remodeling During Blood Pressure Reduction Following Gradual Hypertension Development in Spontaneously Hypertensive Rats

BackgroundCardiovascular disease risk is higher in men than in women. Although sex differences in aortic wall adaptation following antihypertensive treatment have been reported in acute hypertension models, the response after gradually developing hypertension, which mimics human essential hypertension, remains unclear. This study investigated sex differences in aortic wall adaptation following acute blood pressure reduction after gradually developing hypertension. MethodSeventeen-week-old spontaneously hypertensive rats (SHRs) were assigned to the Hypertensive group or the antihypertensive (Reversal) group (N = 5/sex each). The Reversal group received the antihypertensive drug captopril for 4 weeks to maintain systolic blood pressure below 130 mmHg. Age-matched Wistar Kyoto rats (N = 3/sex) served as normotensive (Normal) group. After the experimental period, arterial wall thickness, circumferential wall stress, smooth muscle cell phenotype, and histological changes were evaluated. ResultsAntihypertensive treatment significantly reduced systolic blood pressure in both sexes. Both male and female SHRs exhibited elevated circumferential wall stress during the gradual development of hypertension. In females, antihypertensive treatment significantly reduced medial thickness compared with the Hypertensive group, whereas males showed no reduction. Circumferential wall stress in female Reversal group did not differ significantly from either the Hypertensive or Normal group, whereas males exhibited a significant reduction in circumferential wall stress compared with the Hypertensive group. Furthermore, the reduced collagen area fraction in the Hypertensive group returned to the normotensive levels only in females following antihypertensive treatment. ConclusionThese findings indicate that vascular remodeling induced by gradually developing hypertension is more effectively reversed by antihypertensive treatment in females than in males.

bioengineering↗

bioRxiv2026

Mapping human-macaque encounter potential by integrating visitor-use and macaque-use intensity in Kamikochi, Japan

Managing visitor-wildlife interactions in high-use protected areas requires identifying not only where visitors concentrate but also where visitor use overlaps with wildlife space use. We estimated relative human- macaque encounter potential in Kamikochi, Chubu Sangaku National Park, Japan, where Japanese macaques (Macaca fuscata) and visitors use the same frontcountry landscape. We integrated Mobile Spatial Statistics derived from mobile phone network data, trail-camera counts, and direct-follow location data from macaques along a frontcountry-backcountry gradient. Broad-scale 500-m grid estimates of daytime visitor presence for the 2023 and 2024 open seasons were allocated to 50-m trail sections and adjusted using counts from 10 trail cameras. Automated video counts based on YOLO11 and ByteTrack showed high agreement with manual counts of 100 validation videos (MAE = 0.10 persons/video, MAPE = 1.26%, exact agreement rate = 92.0%). Visitor-use and macaque-use data were converted into kernel density surfaces, and encounter potential was calculated as their normalized product. High encounter potential was concentrated in the central frontcountry: 87.1% of areas with index values [≥] 0.9 fell within the frontcountry and 12.9% within the backcountry. Areas with high visitor use or high macaque use alone did not necessarily show high encounter potential when the two distributions were spatially offset. These results show that spatial overlap provides management information not captured by visitor counts alone. Relative encounter potential can help prioritize patrols, visitor messaging, viewing management, and other interventions in protected areas where wildlife does not consistently avoid heavily used visitor spaces.

zoology↗

bioRxiv2026

Increased Interstitial Flow and Elastic Lamina Degradation Precede Aortic Dissection

AimsTo elucidate the relationship between interstitial flow (IF) and structural changes in the aortic media during the development of aortic dissection (AD). MethodsApolipoprotein E-deficient (ApoE[-/-]) mice infused with angiotensin II (AngII) were used as an AD model, in which AD develops exclusively in the thoracoabdominal aorta but not in the thoracic aorta. To capture characteristics present prior to AD onset, the duration of AngII infusion was shortened to generate Pre-AD group. Normal C57BL/6 mice (Normal group) and ApoE(-/-) mice without AngII infusion (Control group) were also included for comparison. Thoracic and thoracoabdominal aortas were excised from all groups, and IF was measured in vitro in accordance with our previously established methods. ResultsIF velocity was generally smaller than 4 m/s across all groups; however, velocities exceeding 4 m/s was observed predominantly in the thoracoabdominal region of the Pre-AD group. Although mean IF velocity did not differ significantly among groups, the standard deviation differed significantly and was the highest in the thoracoabdominal region of the Pre-AD group. In this region, IF velocity tended to increase with more prolonged AngII administration, indicating acceleration of IF prior to AD onset. Three-dimensional internal structural microscopy revealed fragmentation of the elastic lamina (ELs) and a reduction in elastin density only in the thoracoabdominal region of the Pre-AD group. ConclusionsOur findings suggest that increased IF and EL degradation occur in parallel and together contribute to the initiation of AD.

bioengineering↗

bioRxiv2024

Segregated localization of target-SNARE proteins within presynaptic terminals of Munc18-1 deficient photoreceptors

Sec1/Munc18 family proteins are essential for SNARE-mediated vesicular exocytosis. However, where SNARE proteins are localized in Munc18-1 deficient presynaptic terminals remains unclear due to the rapid degeneration of neurons lacking Munc18-1. Here, we found that removing Munc18-1 from photoreceptor cells did not result in major cellular loss until postnatal day 14, which allowed us to investigate the role of Munc18-1 in endogenous presynaptic terminals. In the absence of Munc18-1, even before major photoreceptor cell degeneration, functional impairments were present. While Munc18-1 was not required for the pre-synaptic enrichment of the t-SNARE proteins syntaxin-3 and SNAP-25, it played a critical role in their proper localization. In wild-type conditions, t-SNAREs are highly colocalized. However, in the absence of Munc18-1, their distribution becomes strikingly segregated. Immuno-electron microscopy revealed that without Munc18-1, syntaxin-3 is retained within various organelle membranes rather than being targeted to synaptic plasma membranes. These findings provide the first evidence that Munc18-1 is important to prevent segregation of syntaxin-3 and SNAP-25 within presynaptic terminals.

neuroscience↗

bioRxiv2023

SNAP-25, but not SNAP-23, is essential for photoreceptor function and survival in mice

Vesicular transport plays critical roles in photopigment delivery at photoreceptor outer segments and glutamate exocytosis at photoreceptor synapses. Previous studies into the role of photoreceptor SNAP proteins are limited in their characterizations into only gene/protein expression and do not delve further into their functional role. Here, we examine the expression and localization of SNAP-23 and SNAP-25 mRNA and protein. Using SNAP-23 and SNAP-25 conditional knockout mice, we further evaluated the morphological and functional consequences that the absence of these proteins has on vision. Although we found that the ubiquitously expressed SNAP-23 showed weak mRNA expression in photoreceptors, removal of SNAP-23 did not result in any observable phenotype. We found that neuronal SNAP-25 is developmentally regulated and SNAP-25 mRNA undergoes mRNA trafficking to the photoreceptor inner segments coinciding with the development of photoreceptor outer segments. Removal of SNAP-25 in photoreceptor cells led to changes in both outer segment protein trafficking and synaptic integrity, resulting in a complete loss of vision in SNAP-25 cKO mice. Our results conclude that SNAP-25, but not SNAP-23, is the essential isoform for photoreceptor survival and function.

neuroscience↗

bioRxiv2023

Mouse model of multiple sclerosis induced by disrupting vesicular transport in oligodendrocytes

Multiple Sclerosis is an autoimmune demyelination disorder with unknown etiology. Despite the myelin damage, the roles of myelinating oligodendrocytes in driving disease progression remain unknown. We hypothesize that disrupting vesicular transport in oligodendrocytes during adolescence will disrupt myelin integrity and causes neuroinflammation. By creating a mouse model of SNAP-23 conditional knockout in mature oligodendrocytes, we showed that impairment in vesicular trafficking in oligodendrocytes causes demyelination. Neuroinflammation with infiltration of peripheral immune T cells into the central nervous system was observed accompanied by demyelination. Mechanistically, SNAP-23 removal in oligodendrocytes caused abnormal axon-myelin structures and impaired myelin protein trafficking, both can contribute to autoimmune activation and demyelination. With our novel animal model, we propose that oligodendrocyte injury is an endogenous early event in triggering Multiple Sclerosis. One-Sentence SummaryImpaired vesicular transport in oligodendrocytes in adults caused demyelination and inflammation driving Multiple Sclerosis

neuroscience↗

bioRxiv2023

Differential Regulation of Excitatory vs Inhibitory Synaptic Release by Complexin/CPX-1 and CAPS/UNC-31 at the C. elegans Neuromuscular Junctions

The excitation and inhibition (E/I) balance at neuromuscular junctions plays a crucial role in coordinating animal motor behavior. Prominent synaptic vesicle secretory regulatory proteins, specifically complexin and CAPS (Calcium-dependent Activator Protein for Secretion), have not garnered sufficient attention for E/I balance regulation. Here, we investigate the roles of complexin/CPX-1 and CAPS/UNC-31 in excitatory vs inhibitory synapses of C. elegans neuromuscular junctions. In our study, cpx-1 null mutants displayed remarkable reduction evoked release in both excitatory and inhibitory synapses. Intriguingly, these mutants exhibited an enhanced level of spontaneous release, particularly within the context of excitatory synapse. This enhancement aligns with its "clamp" role that preventing SV from fusing with the presynaptic membrane. Additionally, a clamping-specific knockin mutant cpx-1({Delta}12), which displayed no alterations in evoked release at either type of synapse, also revealed a biased substantial increase in excitatory spontaneous release. In contrast, unc-31 null mutation, with normal spontaneous release, led to a more pronounced decreased evoked release in the excitatory synapse independent of dense-core vesicle regulation. Intriguingly, we found that the enhanced excitatory spontaneous release observed in cpx-1 mutants was abolished by unc-31 in a Ca2+-dependent manner, implying that UNC-31 is essential for maintaining a high level of spontaneous fusion events. Collectively, our findings unveil a distinct regulatory pattern governing excitatory and inhibitory synaptic release, orchestrated by the interplay of CPX-1 and UNC-31. Notably, we uncover an unforeseen role of UNC-31 in influencing CPX-1s "clamp" function, further adding complexity to the neural dynamics, which may underlie complex behavioral phenotypes observed in C. elegans.

neuroscience↗

bioRxiv2023

Double open syntaxin and UNC-18 P334A mutation leads to excitatory-inhibitory imbalance and impairs multiple aspects of C. elegans behavior

SNARE and Sec/Munc18 proteins are essential in synaptic vesicle exocytosis. Open form t-SNARE syntaxin and UNC-18 P334A are well-studied exocytosis-enhancing mutants. Here we investigate the interrelationship between the two mutations by generating double mutants in various genetic backgrounds in C. elegans. While each single mutation rescued the motility of CAPS/unc-31 and synaptotagmin/snt-1 mutants significantly, double mutations unexpectedly worsened motility or lost their rescuing effects. Electrophysiological analyses revealed that simultaneous mutations of open syntaxin and gain-of-function P334A UNC-18 induces a strong imbalance of excitatory over inhibitory transmission. In liposome fusion assays performed with mammalian proteins, the enhancement of fusion caused by the two mutations individually was abolished when the two mutations were introduced simultaneously, consistent with what we observed in C. elegans. We conclude that open syntaxin and P334A UNC-18 do not have additive beneficial effects, and this extends to C. elegans characteristics such as motility, growth, offspring bared, body size, and exocytosis, as well as liposome fusion in vitro. Our results also reveal unexpected differences between the regulation of exocytosis in excitatory versus inhibitory synapses.

neuroscience↗

bioRxiv2022

Neuronal SNAP-23 scales hippocampal synaptic plasticity and memory

Soluble NSF Attachment protein REceptor (SNARE)-mediated membrane fusion plays a crucial role not only in presynaptic vesicle exocytosis but also in postsynaptic receptor delivery. The latter is considered particularly important for long-term synaptic plasticity and learning and memory, yet underlying mechanisms including the identity of the key SNARE proteins remain elusive. Here, we investigate the role of neuronal Synaptosomal-Associated Protein-23 (SNAP-23) by analyzing pyramidal-neuron specific SNAP-23 conditional knockout (cKO) mice. SNAP-23 immunostaining in postsynaptic spines was effectively decreased in the SNAP-23 cKO hippocampus. Electrophysiological analysis of SNAP-23 deficient neurons using acute hippocampal slices showed normal basal neurotransmission in CA3-CA1 synapses with unchanged AMPA and NMDA currents. Nevertheless, we found theta-burst stimulation induced long-term potentiation (LTP) was vastly diminished in SNAP-23 cKO. Moreover, unlike syntaxin-4 cKO mice in which both basal neurotransmission and LTP decrease manifested changes in a broad set of behavioral tasks, deficits of SNAP-23 cKO is more limited to spatial memory. Our data reveal that neuronal SNAP-23 is selectively crucial for synaptic plasticity and spatial memory without affecting basal glutamate receptor function.

neuroscience↗

bioRxiv2021

Novel method for clarifying faster interstitial flow in the intimal side of the aorta under intraluminal pressurization

Hypertension causes aortic thickening, especially on the intimal side. Although the production of the extracellular matrix is observed, the type of mechanical stress that produces this response remains unclear. In this study, we hypothesize that the interstitial flow causes the thickening. To validate this claim, we proposed a novel method to measure the velocity distribution in the radial direction in the aorta, which has been unclear. A fluorescent dye was introduced in the lumen of the mouse thoracic aorta ex vivo, intraluminal pressure was applied, and a time-lapse image in the radial-circumferential plane was acquired under a two-photon microscope. The flow of the fluorescent dye from the intimal to the adventitial sides in the aorta was successfully observed. The acquired image was converted to a radial-time image (i.e., kymograph), and the flow velocity was quantified by applying the one-dimensional advection-diffusion equation to the fluorescent images. The results revealed a higher interstitial flow velocity in the aortic walls under higher intraluminal pressure and a higher velocity on the more intimal side. Thus, the interstitial flow is a candidate for the mechanical stress causing hyperplasia of the aorta under hypertension.

biophysics↗

bioRxiv2020

Open syntaxin overcomes synaptic transmission defects in diverse C. elegans exocytosis mutants

Assembly of SNARE complexes that mediate neurotransmitter release requires opening of a closed conformation of UNC-64/syntaxin. Rescue of unc-13/Munc13 phenotypes by overexpressed open UNC-64/syntaxin suggested a specific function of UNC-13/Munc13 in opening UNC-64/ syntaxin. Here, we revisit the effects of open unc-64/syntaxin by generating knockin (KI) worms. The KI animals exhibited enhanced spontaneous and evoked exocytosis compared to wild-type animals. Unexpectedly, the open syntaxin KI partially suppressed exocytosis defects of various mutants, including snt-1/synaptotagmin, unc-2/P/Q/N-type Ca2+ channel alpha-subunit, and unc-31/CAPS in addition to unc-13/Munc13 and unc-10/RIM, and enhanced exocytosis in tom-1/Tomosyn mutants. However, open syntaxin aggravated the defects of unc-18/Munc18 mutants. Correspondingly, open syntaxin partially bypasses the requirement of Munc13 but not Munc18 for liposome fusion. Our results show that facilitating opening of syntaxin enhances exocytosis in a wide range of genetic backgrounds, and may provide a general means to enhance synaptic transmission in normal and disease states.

neuroscience↗

bioRxiv2017

Systematic identification of cancer-specific MHC-binding peptides with RAVEN

Immunotherapy can revolutionize anti-cancer therapy if specific targets are available. Recurrent somatic mutations in the exome can create highly specific neo-antigens. However, especially pediatric cancers are oligo-mutated and hardly exhibit recurrent neo-antigens. Yet, immunogenic peptides encoded by cancer-specific genes (CSGs), which are virtually not expressed in normal tissues, may enable a targeted immunotherapy of such cancers. Here, we describe an algorithm and provide a user-friendly software named RAVEN (Rich Analysis of Variable gene Expressions in Numerous tissues), which automatizes the systematic and fast identification of CSG-encoded peptides highly affine to Major Histocompatibility Complexes (MHC) starting from publicly available gene expression data. We applied RAVEN to a dataset assembled from more than 2,700 simultaneously normalized gene expression microarrays comprising 50 tumor entities, with a focus on sarcomas and pediatric cancers, and 71 normal tissue types. RAVEN performed a transcriptome-wide scan in each cancer entity for gender-specific CSGs. As a proof-of-concept we identified several established CSGs, but also many novel candidates potentially suitable for targeting multiple cancer types. The specific expression of the most promising CSGs was validated by qRT-PCR in cancer cell lines and by immunohistochemistry in a comprehensive tissue-microarray comprising 412 samples. Subsequently, RAVEN identified likely immunogenic peptides encoded by these CSGs by predicting the affinity to MHCs. Putative highly affine peptides were automatically crosschecked with the UniProt protein-database to exclude sequence identity with abundantly expressed proteins. The predicted affinity of selected peptides was validated in T2-cell peptide-binding assays in which many showed similar kinetics to a very immunogenic influenza control peptide.\n\nCollectively, we provide a comprehensive, exquisitely curated and validated catalogue of cancer-specific and highly MHC-affine peptides across 50 cancer entities. In addition, we developed an intuitive and freely available software to easily apply our algorithm to any gene expression dataset (https://github.com/JSGerke/RAVENsoftware). We anticipate that our peptide libraries and software constitute a rich resource to accelerate the development of novel immunotherapies.

immunology↗