Biology subjects

Ikegami, K.

Publications and source records attributed to Ikegami, K..

At least 19 recordsLinked to original sources

bioRxiv2026

Large-scale dimensional behavioral profiling dissociates fear memory from locomotor confounds in mice: The necessity of baseline-normalized metrics

Fear conditioning is widely used to assess associative memory in mice, yet percent freezing conflates memory with baseline locomotor and anxiety-related traits. A systematic survey of recent studies (2020-2025) found that fewer than 1% statistically integrate locomotor activity into freezing analyses. Here, we address this gap using a large-scale dataset of >10,000 mice across >160 comparisons, including genetic mutations, pharmacological interventions and aging, tested in 15 standardized behavioral paradigms. Conventional freezing scores covaried strongly with general locomotor activity, obscuring memory-related phenotypes. Multiple factor analysis identified two principal behavioral dimensions, locomotor activity and learning/memory: conventional freezing aligned with the locomotor dimension, whereas freezing subtraction and the activity suppression ratio mapped onto the memory dimension and improved detection of synaptic plasticity phenotypes. These analyses show that baseline locomotor normalization is essential for interpreting fear conditioning as a memory assay and provide an open framework for selecting and reporting locomotor-normalized metrics.

neuroscience↗

bioRxiv2026

RNA polymerase loss by nuclear rupture drives LMNA cardiomyopathy

Localized rupture of the nuclear envelope has recently been reported in various pathologies, including cancer 1,2, neurodegenerative disease 3-5, myocardial infarction 6, as well as dilated cardiomyopathy caused by Lamin A/C gene mutations (LMNA-DCM) 7. Whether and how nuclear rupture contributes to disease remains unknown. Here, we report that nuclear rupture causes global transcriptional deficiency in a mouse model of LMNA-DCM. We observed that ruptured nuclei lost RNA polymerase II, leading to downregulation of numerous genes essential for cardiomyocyte structure and function. We identified endogenous resealing of nuclear rupture as a cardioprotective mechanism in LMNA-DCM mouse hearts. Resealing involved the ESCRT-III membrane remodeling complex recruited to nuclear rupture sites. Resealed nuclei restored transcription while inhibiting ESCRT-III activity accelerated cardiomyopathy. However, resealed nuclei were short-lived: they re-ruptured at twice the rate of resealing. A kinetic model predicted progressive accumulation of ruptured nuclei despite ongoing resealing. Consistently, a human LMNA-DCM heart contained numerous ruptured nuclei at disease presentation. These findings linked nuclear rupture to organ deterioration through global transcriptional deficiency and suggested rupture resealing as a critical modifier of nuclear rupture-associated conditions.

molecular biology↗

bioRxiv2026

Hunting for microsatellite instability in long-read data with Owl

Microsatellite instability (MSI) is a key biomarker of mismatch repair deficiency and response to immunotherapy, yet most existing genomic detection methods are optimized for short-read sequencing and rely on small panels of homopolymer markers, limiting the ability to characterize genome-wide and motif-specific patterns of instability. Here we present Owl, a bioinformatic tool for quantifying MSI from long-read (PacBio) genomic data. Owl leverages a genome-wide marker set of more than 140,000 microsatellite repeats ranging from 1-6 bp in length to measure MSI across a phased genome. Using a wrap-around alignment algorithm, Owl constructs repeat-length distributions at each marker site and flags somatic instability using the coefficient of variation. We applied Owl to screen for markers with stable coverage, phasing, and baseline variation across 131 diverse genomes from the Human Pangenome Reference Consortium, where Owl scores ranged from 1.4% to 5.4% of markers exceeding the instability threshold. When applied to 19 cancer cell lines and one diffuse astrocytoma tumor-normal pair, Owl identified five MSI-high genomes with 15-18% unstable markers and showed close concordance with an Illumina DRAGEN MSI assay for the astrocytoma sample. Motif-level analyses revealed shared enrichment of short homopolymer and dinucleotide (A- and AT-rich) repeats across MSI-high cancers, and additionally uncovered a distinct pattern of elevated GGAA microsatellite instability in Ewing sarcoma cell lines, consistent with the known role of the EWS::FLI1 fusion protein at GGAA-rich regulatory elements. Owl is implemented in Rust and integrated into the PacBio HiFi Somatic workflow, providing a scalable framework for MSI analysis from long-read sequencing focused on repeat instability specifically in tumor samples.

bioinformatics↗

bioRxiv2025

Enhanced release of ciliary extracellular vesicles suppresses cell migration and promotes cell aggregation

A primary cilium is a hair-like organelle that protrudes from the cell surface in many cell types. Growing evidence indicates that extracellular vesicles are released from primary cilia, and research is increasingly focused on defining the functions of these cilia-derived extracellular vesicles (EVs). EVs are known to modulate the behavior of various cancer cells, and structural and functional abnormalities in primary cilia have been reported in multiple cancer types. We previously demonstrated that PANC-1 cells, a human pancreatic ductal adenocarcinoma cell line, acquire enhanced primary cilia formation after surviving solitary culture conditions, and that their cilia contribute to tumor-like cell mass formation. Here, we explored part of the underlying mechanism of this phenotype by investigating the contribution of EVs released from the primary cilia of PANC-1 cells. PANC-1 clones generated by limiting dilution exhibited enhanced ciliogenesis and distinct ciliary morphologies compared with parental cells. These clones also released higher levels of cilia-derived EVs, including an expanded population of freely floating EVs within the culture environment. Biochemical analyses further showed that this increase was selective for primary cilia-derived EVs rather than reflecting a global rise in total EV production. Functionally, EV fractions enriched in cilia-derived EVs suppressed parental PANC-1 cell migration, altered cell morphology, and promoted cell aggregation, mimicking key behavioral traits of solitary condition-surviving PANC-1 clones. Together, these findings identify enhanced release of primary cilia-derived EVs as a distinct feature of PANC-1 cells adapted to solitary growth and suggest their potential involvement in the malignant and metastatic behaviors of pancreatic cancer.

cell biology↗

bioRxiv2025

Structural basis and physiological significance of non-canonical Gs coupling to the prototypical Gi-coupled melatonin MT1 receptor

G protein-coupled receptors (GPCRs) transduce extracellular stimuli into intracellular signals by coupling to various heterotrimeric G proteins. However, the rules governing G protein preference remain largely elusive. MT1 and MT2 are prototypical Gi/o-coupled GPCRs responding to melatonin, a hormone secreted in a circadian manner. We show here that MT1, but not MT2, couples also to Gs proteins in vitro and activates the Gs/cAMP pathway upon long-term melatonin exposure in vivo, mimicking physiological dawn conditions. We solved the cryo-electron microscopy structure of the melatonin-MT1-Gs complex at 3.0[A] resolution, which revealed a strikingly distinct binding mode compared to the MT1-Gi complex. The third intracellular loop of MT1 emerges as a key stabilizer for Gs coupling, a feature previously unrecognized. This is the first solved receptor-Gs complex of a primary Gi-coupled GPCRs, providing new structural and functional insights into G protein selectivity and circadian switch of G protein coupling.

molecular biology↗

bioRxiv2025

Additive framework of hormonal waves explains species and age differences in circadian intraocular pressure rhythm

Elevated intraocular pressure (IOP) is the primary risk factor for glaucoma, yet IOP demonstrates significant circadian rhythms, and their disruption heightens disease susceptibility. A paradox exists in that both diurnal and nocturnal animals experience nocturnal IOP elevation despite their contrasting behavioral chronotypes. Here, we developed a minimal mathematical framework where IOP rhythms arise from the linear superposition of two sinusoidal signals: adrenal glucocorticoids (GC) and norepinephrine (NE) from the superior cervical ganglion. In both diurnal and nocturnal species, NE levels increase at night, while GC levels peak oppositely in the morning and evening. A meta-analysis of published datasets showed that IOP peaks in the early night for nocturnal animals and in the late night for diurnal animals, aligning with the predicted maxima of the combined GC and NE sine waves. In aged mice and following superior cervical ganglionectomy, IOP rhythms shifted in phase and decreased in amplitude and mean level; these changes were accounted for by selectively reducing the NE components amplitude in the model. Conversely, in diurnal humans, aging results in a delayed IOP phase, which is replicated by diminishing NE amplitude. Thus, species differences, age-related changes, and the effects of sympathetic ablation on IOP can be coherently explained by the combination of the two zeitgeber signals with distinct phases. This straightforward yet robust framework offers a unifying concept for the circadian regulation of IOP across species and may inform the development of novel diagnostic algorithms and chronotherapeutic strategies for glaucoma. SignificanceGlaucoma is a leading cause of irreversible blindness, and its major risk factor, intraocular pressure (IOP), exhibits a circadian rhythm. A long-standing paradox is that IOP rises at night in both diurnal humans and nocturnal rodents, despite their opposite activity patterns. We showed that IOP rhythms can be explained by the superposition of two sine waves representing adrenal glucocorticoid and sympathetic norepinephrine rhythms. This framework parsimoniously accounts for species differences, aging effects, and the impact of sympathetic ganglionectomy on the IOP. By reducing a complex physiological process to the interaction of two entrainment signals with distinct phases, our model provides new mechanistic insights into circadian ocular physiology and highlights potential strategies for age-specific monitoring and therapeutic timing in glaucoma.

physiology↗

bioRxiv2025

Internal desynchrony of the circadian clock system in middle-aged mice under social jet lag-like conditions

Social jet lag (SJL) refers to the discrepancy in sleep patterns between weekdays and weekends, leading to a misalignment between the internal clock and social time. In this study, we investigated the effects of weekly shifts in light-dark (LD) conditions: two days per week with 6-h delayed LD cycles (simulating Saturday and Sunday), followed by a 6-h advance on Monday. Core body temperature rhythms rapidly entrained to the delayed LD cycles on weekends, and these delayed rhythms persisted even after the LD cycle was advanced on Monday. In contrast, plasma corticosterone rhythms on Mondays were aligned with the LD cycle but exhibited reduced amplitude. In the livers of SJL mice on Monday, the expression rhythms of Per1, Per2, and Hsp70 were delayed by 3-5 h compared to that in the controls, whereas Rev-erb expression rhythms remained comparable to those of the controls. The expression of lipid and glucose metabolism-related genes in the liver showed either delayed rhythms or no significant changes. To determine whether the dissociation of gene expression rhythms resulted from gene-specific responses to circadian body temperature and hormonal signals, we conducted ex vivo culture experiments using mouse liver slices. High-temperature stimulation induced Per2 and Hsp70 expression, while dexamethasone induced Per1 expression. High temperature and dexamethasone affected distinct sets of metabolic genes, whereas insulin induced only minor changes. Moreover, these responses were strongly influenced by the age and light exposure of the mice. We also examined the effect of weekly housing by providing environmental enrichment (EE), which had minimal impact on circadian parameters but promoted anti-aging effects on bone density and behavior. Overall, our findings indicate that weekly shifts in LD cycles induce internal desynchronization within the hepatic molecular clock and metabolic pathways by uncoupling core body temperature rhythms, hormonal rhythms, and gene-specific responses to stimuli.

physiology↗

bioRxiv2025

Cell-cycle dynamics of nascent transcription and mature RNA accumulation are concordant in normal fibroblasts

Cell-cycle dynamics of gene expression are fundamental to life, yet their origin remains unclear. A prevailing model, derived from cancer cells, posits that transcription occurs in one cell cycle phase, while mature RNA accumulates in subsequent phases, suggesting temporal segregation of transcriptional regulation and RNA abundance. Whether this paradigm applies to normal human cells is unclear. Here, we co-profiled nascent transcription and mature RNAs in cycling human fibroblasts. The two dynamics were strongly concordant, with no evidence of a lag extending cell-cycle phases. Our data suggest a widespread transcription-to-maturation lag is not a general feature of human cells.

genomics↗

bioRxiv2025

Primary Cilium-dependent Humoral Bioactive Factors Acts in a Paracrine Manner to Control Fibroblast Cell Migration

The primary cilium is classically recognized as a signal-reception hub, yet its role in mediating cell-to-cell communication via signal spread remains poorly defined. Here, we uncover a previously unrecognized paracrine function of the primary cilium in fibroblasts. Conditioned medium from ciliated wild-type NIH/3T3 cells enhanced wound healing in primary cilium-deficient fibroblasts, in contrast to conditioned medium derived from primary cilium-deficient NIH/3T3-Kif3a-KO or NIH/3T3-Dync2h1-KO cells. Fractionation of conditioned medium revealed that the wound healing activity resided predominantly in the 100K x g soluble supernatant (Sup-100K), rather than in extracellular vesicle (EV) fractions. Untargeted metabolomic analysis identified lysophosphatidylcholine (LPC) (14:0) as a key bioactive metabolite enriched in WT-Sup-100K secretome. Supplementation of LPC(14:0) restored wound healing capacity in NIH/3T3-Kif3a-KO cells to levels comparable to WT-Sup-100K treatment. Transcriptomic profiling of target cells revealed that WT-Sup-100K upregulated expression of extracellular matrix (ECM)-associated genes, including Ogn, Igf2, and Mfap4, while EVs modestly enhanced early ECM remodeling via induction of Nid2. Together, these findings demonstrate that the primary cilium coordinates a wound healing secretome in fibroblasts through the regulated release of LPC(14:0) and other soluble factors that activate ECM-remodeling pathways in recipient cells. This work expands the functional repertoire of the primary cilium and establishes its critical role in coordinating paracrine regenerative signaling.

cell biology↗

bioRxiv2025

Nocturnal intraocular pressure rise is regulated by norepinephrine via RHOB

Intraocular pressure (IOP), a key factor in glaucoma development, is regulated by aqueous humor (AH) dynamics, with inflow from the ciliary body and outflow through the trabecular meshwork (TM). IOP has a circadian rhythm entrained by sympathetic norepinephrine (NE) from the superior cervical ganglion. Herein, we investigated its underlying regulatory mechanisms in the TM. Through comprehensive gene expression analysis of human TM cells and mouse eyes, we identified 18 genes upregulated by NE stimulation, including the small GTPase RAS homologous protein B (RHOB). Promoter assays revealed RHOB upregulation via the cyclic adenosine monophosphate (cAMP) response element on its promotor. NE stimulation for 6-9 h increased RHOB level and cellular adhesion, and suppressed liquid permeability in the TM cells, indicating a time-dependent effect. RHOB deficiency increased TM macrophage phagocytosis and eliminated NE-induced suppression of phagocytosis and permeability, whereas RHOB overexpression had the opposite effect. Instillations of RHO or RHO-kinase inhibitors to mice eye reduced nocturnal and NE-induced IOP elevation. Our findings suggest that NE can elevate IOP via RHOB-mediated inhibition of TM phagocytosis, positioning RHOB as a potential glaucoma treatment target and IOP rhythm regulator.

pathology↗

bioRxiv2024

Nutrient starvation activates ECM remodeling gene enhancers associated with inflammatory bowel disease risk in fibroblasts

Nutrient deprivation induces a reversible cell cycle arrest state termed quiescence, which often accompanies transcriptional silencing and chromatin compaction. Paradoxically, nutrient deprivation is associated with activated fibroblast states in pathological microenvironments in which fibroblasts drive extracellular matrix (ECM) remodeling to alter tissue environments. The relationship between nutrient deprivation and fibroblast activation remains unclear. Here, we report that serum deprivation extensively activates transcription of ECM remodeling genes in cultured fibroblasts, despite the induction of quiescence. Starvation-induced transcriptional activation accompanied large-scale histone acetylation of putative distal enhancers, but not promoters. The starvation-activated putative enhancers were enriched for non-coding genetic risk variants associated with inflammatory bowel disease (IBD), suggesting that the starvation-activated gene regulatory network may contribute to fibroblast activation in IBD. Indeed, the starvation-activated gene PLAU, encoding uPA serine protease for plasminogen and ECM, was upregulated in inflammatory fibroblasts in the intestines of IBD patients. Furthermore, the starvation-activated putative enhancer at PLAU, which harbors an IBD risk variant, gained chromatin accessibility in IBD patient fibroblasts. This study implicates nutrient deprivation in transcriptional activation of ECM remodeling genes in fibroblasts and suggests nutrient deprivation as a potential mechanism for pathological fibroblast activation in IBD. HIGHLIGHTS- Serum starvation transcriptionally activates ECM remodeling genes in fibroblasts. - Fibroblast starvation activates putative distal enhancers associated with ECM remodeling genes. - Starvation-activated putative enhancers are enriched for inflammatory bowel disease (IBD) risk variants. - PLAU enhancer and expression are activated in IBD intestinal fibroblasts, as in starved fibroblasts.

genomics↗

bioRxiv2024

The Splice Index as a prognostic biomarker of strength and function in myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is a slowly progressive, multisystemic disorder caused by a CTG repeat expansion in the DMPK 3UTR that leads to global dysregulation of alternative splicing. Here, we employed a composite RNA splicing biomarker called the Myotonic Dystrophy Splice Index (SI), which incorporates 22 disease-specific splice events that sensitively and robustly assesses transcriptomic dysregulation across the disease spectrum. Targeted RNA sequencing was used to derive the SI in 95 muscle biopsies of the tibialis anterior collected from DM1 individuals with baseline (n = 52) and 3-months (n = 37) outcomes. The SI had significant associations with timepoint matched measures of muscle strength and ambulation, including ankle dorsiflexion strength (ADF) and 10-meter run/fast walk speed (Pearson r = -0.719 and -0.680, respectively). Linear regression modeling showed that the combination of baseline ADF and SI was predictive of strength at 3-months (adjusted R2 = 0.830) in our cohort. These results indicate the SI can reliably capture the association of disease-specific RNA mis-splicing to physical strength and mobility and may be predictive of future function.

molecular biology↗

bioRxiv2024

RNA mis-splicing in children with myotonic dystrophy is associated with physical function

ObjectivesDysregulated RNA alternative splicing is the hallmark of myotonic dystrophy type 1 (DM1). However, the association between RNA mis-splicing and physical function in children with the most severe form of disease, congenital myotonic dystrophy (CDM), is unknown. Methods82 participants (42 DM1 adults & 40 CDM children) with muscle biopsies and measures of myotonia, motor function, and strength were combined from five observational studies. Data were normalized and correlated with an aggregate measure of alternative splicing dysregulation, [MBNL]inferred in skeletal muscle biopsies. Multiple linear regression analysis was performed to predict [MBNL]inferred using clinical outcome measures alone. Similar analyses were performed to predict 12-month physical function using baseline metrics. ResultsMyotonia (measured via vHOT) was significantly correlated with RNA mis-splicing in our cross-sectional population of all DM1 individuals; CDM participants alone displayed no myotonia despite a similar range of RNA mis-splicing. Measures of motor performance and muscle strength were significantly associated with [MBNL]inferred in our cohort of all DM1 individuals and when assessing CDM children independently. Multiple linear regression analyses yielded two models capable of predicting [MBNL]inferred from select clinical outcome assessments alone in all subjects (adjusted R2 = 0.6723) or exclusively in CDM children (adjusted R2 = 0.5875). InterpretationOur findings establish significant correlations between skeletal muscle performance and a composite measure of alternative splicing dysregulation, [MBNL]inferred, in DM1. The strength of these correlations and the development of the predictive models will assist in designing efficacious clinical trials for individuals with DM1, particularly CDM.

genetics↗

bioRxiv2024

Excessive F-Actin and Microtubule Formation Mediates Primary Cilia Shortening and Loss in Response to Increased Extracellular Osmotic Pressure

The primary cilium is a small organelle protruding from the cell surface and is recognized as an antenna for signals from the extracellular milieu. Maintenance of primary cilia structure is crucial for proper behaviors of cells, tissues, and organs. While a dozen of studies have reported that several genetic factors impair the structure of primary cilia, evidence for environmental stimuli affecting primary cilia structures is limited. Here, we investigated an extracellular stress that affected primary cilia morphology and its underlying mechanisms. Hyperosmotic shock with increased extracellular sodium chloride concentration induced shortenings and disassembly of primary cilia in murine intramedullary collecting ducts cells. The shortening of primary cilia caused by hyperosmotic shock followed a loss of axonemal microtubules and delocalization of pericentriolar materials (PCMs). The primary cilia shortening/disassembly and PCMs delocalization were reversible. In parallel with these hyperosmotic shock-induced changes of primary cilia and PCMs, excessive microtubule and F-actin formation occurred in the cytoplasm. A microtubule-disrupting agent, Nocodazole, prevented the hyperosmotic shock-induced primary cilia disassembly partially, while preventing the delocalization of PCMs almost 100%. An actin polymerization inhibitor, Latrunculin A, also prevented partially the hyperosmotic shock-induced primary cilia shortening and disassembly, while preventing the delocalization of PCMs almost 100%. Taken together, we demonstrate that hyperosmotic shock induces reversible morphological changes in primary cilia and PCMs in a manner dependent on excessive formation of microtubule and F-actin.

cell biology↗

bioRxiv2023

The cGAS-STING pathway is dispensable in a mouse model of LMNA-cardiomyopathy despite nuclear envelope rupture

Nuclear envelope (NE) ruptures are emerging observations in Lamin-related dilated cardiomyopathy, an adult-onset disease caused by loss-of-function mutations in Lamin A/C, a nuclear lamina component. Here, we tested a prevailing hypothesis that NE ruptures trigger pathological cGAS-STING cytosolic DNA-sensing pathway, using a mouse model of Lamin-cardiomyopathy. Reduction of Lamin A/C in cardiomyocytes of adult mice caused pervasive NE ruptures in cardiomyocytes, preceding inflammatory transcription, fibrosis, and fatal dilated cardiomyopathy. NE ruptures were followed by DNA damage accumulation without causing immediate cardiomyocyte death. However, cGAS-STING-dependent inflammatory signaling remained inactive. Deleting cGas or Sting did not rescue cardiomyopathy. The lack of cGAS-STING activation was likely due to the near absence of cGAS expression in adult cardiomyocytes at baseline. Instead, extracellular matrix (ECM) signaling was activated and predicted to initiate pro-inflammatory communication from Lamin-reduced cardiomyocytes to fibroblasts. Our work nominates ECM signaling, not cGAS-STING, as a potential inflammatory contributor in Lamin-cardiomyopathy.

molecular biology↗

bioRxiv2023

Circadian oscillation in primary cilium length by clock genes regulate fibroblast cell migration

Various mammalian cells have autonomous cellular clocks that are produced by the transcriptional cycle of clock genes. Cellular clocks provide circadian rhythms for cellular functions via transcriptional and cytoskeletal regulation. The vast majority of mammalian cells possess a primary cilium, an organelle protruding from the cell surface. Here, we investigated the little-known relationship between circadian rhythm and primary cilia. The length and number of primary cilia showed circadian dynamics both in vitro and in vivo. The circadian rhythm of primary cilium length was abolished by SR9011 and Bmal1 knockout. A centrosomal protein, pericentrin, transiently accumulates in centriolar satellites, the base of primary cilia at the shortest cilia phase, and induces elongation of primary cilia at the longest cilia phase in the circadian rhythm of primary cilia. In addition, rhythmic cell migration during wound healing depends on the length of primary cilia and affects the rate of wound healing. Our findings demonstrate that the circadian dynamics of primary cilia length by clock genes control fibroblast migration and could provide new insights into chronobiology.

cell biology↗

bioRxiv2022

A mouse model of insomnia with sleep apnea

Obstructive sleep apnea (OSA) patients are exposed to nighttime hypoxia during sleep by intermittent airway closure and feel daytime strong sleepiness. Strangely, insomnia co-occur in some OSA patients, which is called co-morbid insomnia and sleep apnea (COMISA). Here, we show activity responses to daytime hypoxia (DHx) in nocturnal mice were comparable to daytime sleepiness and co-occurring nighttime insomnia in COMISA. DHx reduced activity in active phase (AP) and increased following activity in activity ending phase (AEP). This down-and-up activity response (DUR) by DHx was also observed in molecular clock deficient Cry1 and Cry2 double knockout mice (CryDKO) expressing nighttime activity rise under light-dark cycle (LD) and not observed in arrhythmic CryDKO under constant darkness (DD). When daytime timing hypoxia was exposed at transition from LD to DD, about every 6 h down and up and down wavelike activity responses appeared in arrhythmic CryDKO. Results indicate this wavelike response and AP activity overlap and cause DUR in rhythmic mice. DHx increased plasma corticosterone and this increase antagonized AP activity reduction by DHx. DHx reduced forebrain adenosine and morning adenosine inhibition by caffeine induced DUR. Adenosine inhibition by caffeine or istradefylline at transition from LD to DD induced wavelike response in CryDKO. It is possible that wavelike response is damped oscillation because, interestingly, chronic caffeine treatment induced circasemidian and/or circadian activity rhythms in arrhythmic CryDKO. Evening caffeine attenuated DUR by DHx, which suggested adenosine inhibition chronotherapy may improve OSA/COMISA symptoms. Our animal model will be useful to understand COMISA. SignificanceObstructive sleep apnea patients (OSA) are exposed to nighttime hypoxia during sleep. OSA feels daytime strong sleepiness and increases risk of many diseases. Insomnia occurs in not a few OSA, which is called comorbid insomnia and sleep apnea (COMISA). We show here a mouse model of COMISA. In mice, daytime hypoxia exposure induced following down and up activity response (DUR), activity reduction in active phase and increase in activity ending phase, which corresponded to sleepiness and insomnia in COMISA. We found DUR was clock gene independent and might be driven by circasemidian system. Glucocorticoid and forebrain adenosine response were involved in DUR. Caffeine chronotherapy was effective in DUR. Our model may be useful to understand COMISA.

physiology↗

bioRxiv2022

Plap-1/Aspn lineage tracing and single-cell transcriptomics reveals cellular dynamics in the periodontal ligament

Periodontal tissue supports teeth in the alveolar bone socket via fibrous attachment of the periodontal ligament (PDL). The PDL contains periodontal fibroblasts and stem/progenitor cells, collectively known as PDL cells (PDLCs), on top of osteoblasts and cementoblasts on the surface of alveolar bone and cementum, respectively. However, the characteristics and lineage hierarchy of each cell type remain poorly defined. This study identified periodontal ligament associated Protein-1 (Plap-1/Aspn) as a PDL-specific extracellular matrix. We generated knock-in mice expressing CreERT2 and GFP specifically in Plap-1-positive PDLCs. Genetic lineage tracing confirmed the long-standing hypothesis that PDLCs differentiated into osteoblasts and cementoblasts. A PDL single-cell atlas defined cementoblasts and osteoblasts as Plap-1-Ibsp+Sparcl1+ and Plap-1-Ibsp+Col11a2+, respectively. Other populations such as Nes+ mural cells, S100B+ Schwann cells, and other non-stromal cells were also identified. RNA velocity analysis suggested that Plap-1highLy6a+ cell population was the source of PDLCs. Lineage tracing of Plap-1+ PDLCs during the periodontal injury model showed periodontal tissue regeneration by PDLCs. Our study defines diverse cell populations in PDL and clarifies the role of PDLCs in periodontal tissue homeostasis and repair.

developmental biology↗