Biology subjects

Suzuki, N.

Publications and source records attributed to Suzuki, N..

At least 19 recordsLinked to original sources

bioRxiv2026

Genomic SEM reveals shared genetic architecture and expands locus discovery for locomotor activity in heterogeneous stock rats

Locomotor response to a novel environment is a heritable, addiction-relevant behavioral phenotype in rodents. We characterized its genetic basis in 9,341 male and female heterogeneous stock (HS) rats from eight studies. Locomotor activity was heritable across studies, while pairwise genetic correlations were positive but variable, indicating shared yet nonidentical genetic influences. Given nonuniform genetic architecture, we compared three complementary approaches to locus discovery that analyzed SNP effects 1) on a pooled locomotor phenotype (MEGA), 2) across studies under a fixed-effect model (METAL), or 3) on a shared genetic factor (Genomic SEM). To ensure comparability, all three locus-discovery approaches were applied to a common subset of seven studies. Together, these approaches identified 38 loci, with both convergence and method-specific discovery across analyses. Genomic SEM identified 31 loci, compared to 8 for MEGA and 13 for METAL. To interpret the loci, we integrated brain molecular QTLs, predicted coding and splice consequences, and open-field locomotor phenotypes from knockouts of orthologous mouse genes. Our results highlighted established neurobehavioral candidates spanning locomotor and reward-related biology (Negr1 and Lmo4), serotonergic signaling (Htr1b), and GABAergic signaling (Gabrg2), as well as relatively novel genes including Tcerg1l, Pcdh10, and Tmem132e. Our results illustrate how Genomic SEM can integrate genetically correlated yet heterogeneous behavioral measures and enable discovery of loci underlying their shared genetic architecture, highlighting its utility for complex-trait studies in rodents.

genetics↗

bioRxiv2026

Rice brown spot resistance gene bsr1 also confers resistance to bacterial blight by suppressing sucrose efflux

Brown spot (BS), caused by the fungal pathogen Bipolaris oryzae, is a major disease threatening global rice production. However, the genetic basis of host BS resistance remains unclear. Here, we identified brown spot resistance 1 (bsr1), a quantitative trait locus conferring BS resistance, by map-based cloning. We show that bsr1 encodes a sucrose transporter and that a near-isogenic line carrying bsr1 (bsr1-NIL) in the susceptible Koshihikari genetic background exhibited resistance to BS by suppressing sucrose efflux into the apoplast after pathogen attack. Furthermore, bsr1-NIL also showed strain-specific resistance to bacterial blight caused by Xanthomonas oryzae pv. oryzae through the same mechanism. These findings demonstrate that bsr1 confers dual resistance to fungal and bacterial diseases by regulating sucrose efflux. Our study identifies a previously unrecognized mechanism underlying resistance to both BS and bacterial blight and highlights bsr1 as a promising target for breeding disease-resistance rice cultivars. Rice (Oryza sativa L.) is a staple food for more than half of the worlds population1. Brown spot (BS), caused by the fungus Bipolaris oryzae, is one of the most prevalent fungal diseases of rice, and its incidence has increased under global warming2. BS infects coleoptiles, leaves, leaf sheaths, panicle branches, glumes, and spikelets, and severe infection can substantially reduce grain yield.

plant biology↗

bioRxiv2026

Leucine Aminopeptidase 3 Regulates Skeletal Muscle Mitochondrial Homeostasis with Sex-Dependent Metabolic Consequences

Skeletal muscle homeostasis depends on the coordinated regulation of protein turnover and mitochondrial quality control; however, the molecular mechanisms linking these processes remain unclear. In this study, we examined the physiological role of leucine aminopeptidase 3 (LAP3), a post-proteolytic aminopeptidase, using constitutive LAP3-deficient mice. LAP3 deficiency preferentially affected skeletal muscle, causing reduced muscle mass and mitochondrial enlargement in both sexes. Female LAP3-deficient mice also showed reduced myofiber size, impaired endurance capacity, increased energy expenditure, elevated lipid oxidation, and lipid droplet accumulation adjacent to the mitochondria. Proteomic analyses revealed remodeling of pathways related to lipid metabolism and protein homeostasis. Consistent with these findings, LAP3 deficiency increased the expression of Pink1 and Tax1bp1 and promoted the accumulation of ubiquitinated proteins, suggesting alterations in mitochondrial quality control and proteostatic regulation. In cultured myogenic cells, LAP3 localized to mitochondrial fractions, and both LAP3 knockdown and overexpression altered mitochondrial morphology. Taken together, these results identify LAP3 as a regulator of skeletal muscle homeostasis and support a role for LAP3 in linking intracellular peptide turnover to mitochondrial homeostasis, with female skeletal muscle showing greater susceptibility to LAP3 deficiency.

physiology↗

bioRxiv2026

Divergent mechanics of inner ear morphogenesis are coupled to developmental tempo over vertebrate evolution

Vertebrate embryos vary in size and developmental tempo based on reproductive strategies; however, organs of ancient origin, such as the eye and inner ear, remain highly conserved in structure and function. How both diverse embryonic traits and conserved organ development occur remains unclear. Here, we identify divergent morphogenetic mechanics of inner ear development, particularly in vesicular primordium expansion, in 12 species representing the major vertebrate lineages. Differences in cell volume regulation determine tissue growth mechanics, which diversify the expansion process but yield a conserved morphological outcome. Heterochronic shifts in organogenesis allow this regulation to evolve in coordination with a prolonged developmental period. These findings suggest that alternative morphogenetic mechanics mitigate the effects of diversified embryonic traits, thereby ensuring consistent morphological outcomes for highly conserved organs.

evolutionary biology↗

bioRxiv2026

The REFLEX system enables in vivo identification of perivascular angiogenic macrophages in the heart

Direct identification of physically interacting cells in vivo remains challenging because conventional interactome analyses infer signaling partners from transcriptomes and cannot reveal which cells are in direct contact. In pressure-overload induced cardiac remodeling, VEGF-A plays a central role in the maintenance of vascular integrity and cardiac function. However, the cell type which produces VEGF-A and how the VEGF-A peptide is delivered to vascular endothelial cells remains unclear. Here, we developed a genetically encoded platform that combines REFLEX mice with HUNTERuni-seq, enabling unbiased detection and transcriptional profiling of the cells that physically interact with vascular endothelial cells. The REFLEX and HUNTERuni-seq approach identified subpopulations of Vegfa positive macrophages which we named perivascular angiogenic macrophages (PVAMs). Although the amount of VEGF-A in PVAMs is small, loss of VEGF-A in PVAMs impaired angiogenesis and systolic function during pressure overload. We additionally show that direct contact between PVAMs and endothelial cells is critical for the delivery of VEGF-A to endothelial cells. Conventional interactome analysis predicted that cardiomyocytes as dominant sources of VEGF-A in the heart. However, cardiomyocyte Vegfa deletion had no effect on capillary density nor systolic function in a model of heart failure. These results suggest that VEGF-A signaling does not rely on free diffusion through the interstitium and that cellular proximity and physical contact between PVAMs and endothelial cells are the key determinants of effective signal delivery. Together, these findings establish REFLEX and HUNTERuni-seq as a versatile platform for uncovering biologically critical cell-to-cell interactions and provide new insight into intercellular communication in pathological tissue contexts.

cell biology↗

bioRxiv2025

HypoxamicroRNA-210 protects against hepatic steatosis by inhibiting CIDEC expression

Background and AimsMetabolic dysfunction-associated steatotic liver disease (MASLD) is a major global health burden. Although hypoxia is known to contribute to MASLD pathogenesis, the role of hypoxia signaling remains poorly defined. We investigated whether HypoxamicroRNA-210 (miR-210), a key hypoxia-inducible microRNA, regulates hepatic lipid metabolism and MASLD development. MethodsSerum miR-210 levels were quantified in MASLD patients and matched controls. Human hepatic spheroids and HepG2 cells were exposed to fatty acids to assess miR-210 induction and lipid accumulation. miR-210 knockout mice were fed a Western diet to evaluate hepatic steatosis and transcriptomic changes using RNA sequencing. RNA pull-down and 3UTR-driven luciferase reporter assays were employed to identify miR-210 targets. Functional effects of miR-210 mimic were examined in knockout mice, db/db mice, and in vitro human hepatic spheroid models. ResultsSerum miR-210 levels were significantly reduced in MASLD patients compared with matched controls. Consistently, human hepatic spheroids did not appropriately increase miR-210 expression in response to fatty acid-induced intracellular hypoxia. This blunted miR-210 response contributed to hepatic lipid accumulation, as loss of miR-210 in a mouse model of MASLD led to increased hepatic lipid deposition and activation of lipid metabolic pathways. We identified CIDEC as a direct miR-210 target mediating its inhibitory effects on hepatic lipid accumulation, and restoring miR-210 expression suppressed CIDEC and reduced hepatic lipid content in knockout mice on a Western diet. Moreover, miR-210 attenuated lipid accumulation in both in vitro human hepatic spheroids and in vivo db/db mice models of MASLD. ConclusionsmiR-210 protects against hepatic steatosis by inhibiting CIDEC expression, suggesting miR-210-CIDEC axis as a promising therapeutic target for reducing hepatic lipid accumulation and preventing MASLD progression. Impact and ImplicationsThis study addresses a critical gap in understanding how hypoxia signaling shapes MASLD and uncovers a novel pathogenic mechanism of hepatic steatosis arising from fatty acids-induced dysregulation of miR-210. Impaired hypoxia responses, via blunted miR-210 induction, contribute to hepatic lipid accumulation through upregulation of CIDEC, a newly identified target of miR-210. These findings establish miR-210 as a novel regulator of hepatic lipid homeostasis and underscore its therapeutic potential. Interventions aimed at restoring miR-210 function in the liver may offer a promising strategy to ameliorate hepatic steatosis and prevent MASLD progression.

molecular biology↗

bioRxiv2025

Human-specific fast synaptic kinetics enable rapid detection of predictive features

Humans can discern the underlying principles in complex environments, but the cellular basis of this ability is unclear. By comparing layer 2/3 cortical pyramidal neurons in five mammals (mouse, rat, marmoset, macaque and human), we found that human neurons exhibited distinctively faster kinetics of excitatory synaptic transmissions. In a computational model, neurons with human-type synapses detected hidden patterns more quickly in noise, and this superiority was only evident in unsupervised learning. Tracking synaptic weights revealed that human synapses were potentiated sharply and persistently by the patterns, while macaque-type synapses were broadly potentiated, which were easily eroded. These data suggest that the human-specific acceleration of synaptic kinetics enables the rapid extraction of latent structures in complex environments, providing a cellular basis for our efficient cognitive abilities.

neuroscience↗

bioRxiv2025

Tetraploid Caenorhabditis elegans embryos exhibit enhanced tolerance to osmotic stress

Polyploidy is a widespread phenomenon in development and evolution and is often associated with altered cellular physiology and developmental robustness. However, the influence of genome doubling on embryonic robustness to environmental stress remains poorly understood. Here, we investigated developmental traits and osmotic responses in tetraploid Caenorhabditis elegans embryos. Tetraploid animals exhibited enlarged body and tissue sizes and produced embryos with approximately 1.6-fold greater volume than diploids, accompanied by moderately delayed development and partial embryonic arrest. When exposed to a range of osmotic environments, both diploid and tetraploid embryos swelled or shrank in response to external osmolarity. Strikingly, tetraploid embryos at the early stage maintained normal cell division across a broader range of osmotic conditions than diploids. Quantitative analyses further revealed that tetraploid embryos exhibit reduced cytoplasmic mass density, largely reflecting lower protein concentration, while lipid and RNA levels remain unaffected. These compositional differences likely buffer volume fluctuations and underlie the enhanced osmotic tolerance of tetraploid embryos. Our findings demonstrate that genome doubling reshapes embryonic cellular physiology in a non-proportional manner to ploidy, thereby enhancing robustness during early development.

developmental biology↗

bioRxiv2025

Visualization of the microstructure and distribution of follicles in deep human ovaries using speckle-modulated optical coherence microscopy

Ovarian tissue cryopreservation (OTC) and transplantation (OTT) are the only fertility preservation (FP) options for children, adolescents, and young adults (CAYA) who dont enough time until treatment of primary disease. OTC is still unestablished FP options, but it is expected that selective preservation of ovarian tissue with high follicle density will enhance pregnancy efficiency. Despite its value as a noninvasive follicle visualization method, optical coherence microscopy (OCM) lacks sufficient spatial resolution, imaging depth, and noise suppression capabilities to resolve fine follicular structures in deep ovarian tissue. In this study, we applied speckle modulation to a wavelength-swept OCM optical system in the near-infrared region to visualize the fine structure of follicles distributed in deep tissues. OCM images of 4-day-old mice revealed dense superficial-layer distributions of primordial follicles. These follicles were distinguishable from primary follicles, which were surrounded by a single layer of granulosa cells. In 14-day-old ovarian tissue, secondary follicles exhibited spatial dominance, and the fine structures constituting the follicles were successfully visualized. In ovarian tissues extracted from a patient diagnosed with acute myeloid leukemia (AML), the fine structures of primordial follicles were visualized to a depth of 300 m, and a comparison with HE staining revealed that follicle density varied significantly depending on the ovarian regions. Speckle modulation-assisted OCM visualized the microstructure of follicles with varying degrees of maturation in human ovaries at the depth necessary for clinical application. Overall, this technology enables quantitative ovarian reserve assessment and selective cryopreservation of ovarian tissue rich in immature follicles, supporting FP in CAYA diagnosed with cancer.

bioengineering↗

bioRxiv2025

Prevalence, Production and the Role of Staphylococcus aureus Superantigens in Cystic Fibrosis Lung Disease.

Staphylococcus aureus (SA), the most common cystic fibrosis (CF) lung pathogen, is uniquely capable of producing superantigen (SAg) exotoxins, which are the most potent activators of the immune system. Although the proinflammatory roles of SA-SAgs is well-established, their role in the immunopathogenesis of CF lung disease is unexplored. Herein, we demonstrate that 60-80% of pediatric and adult CF SA isolates carried at least one SA-SAg gene, with the former harboring potent SA-SAgs (Staphylococcal enterotoxin A and B) more frequently (30-60%). Biofilms of clinical SA isolates readily produced biologically active SA-SAgs in artificial sputum medium and purified SA-SAgs retained their bioactivity in human CF sputum in vitro. Repeated intratracheal challenge with purified SA-SAgs induced a robust pulmonary inflammatory response in CF mouse models ({beta}ENAC and CFGC transgenic mice) expressing HLA-DR3 in a dose-dependent manner, with the low dose favoring a type 2 eosinophilic lung inflammatory response, and a high dose eliciting a type 1 inflammatory response with neutrophilic lung inflammation and higher mortality. In vivo neutralization of IFN-{gamma} also promoted SA-SAg-driven type 2 inflammation. Intratracheal infection with sub-lethal dose of a clinical SA isolate producing SEB, but not the SEB-deficient mutant isogenic SA strain, also elicited an eosinophilic inflammatory response.

immunology↗

bioRxiv2025

Muc6-expressing gastric isthmus progenitors contribute to regeneration and metaplasia supported by myeloid-mesenchymal interactions

Gastric mucosal homeostasis is maintained by tissue-resident stem and progenitor cells residing in the isthmus region. Following mucosal injury, surviving cells contribute to regeneration, coinciding with characteristic pathological changes such as atrophic gastritis and metaplasia. To comprehensively understand the cellular dynamics involved in this process, we performed single-cell and spatial transcriptomics using newly generated transgenic mice. In human samples and mouse models, loss of gastric chief cells precedes, and even induces, loss of parietal cells during the progression of atrophy and metaplasia, validating the causal relationship underlying the decrease of these two lineages. Single-cell analysis confirmed robust stemness and metaplastic changes in the Muc6-expressing neck lineage following either chief or parietal cell ablation, and lineage-tracing experiments revealed that Muc6-expressing isthmus progenitors serve as a source of metaplasia and regeneration. Mechanistically, mucosal injury recruits IL-1-expressing myeloid cells, which stimulates NRG1 production in stromal fibroblasts, leading to mucosal proliferation and regeneration mediated by Myc activation in isthmus progenitors. These findings highlight the injury-responsible stem cell-like function of Muc6-expressing isthmal progenitors, which play a critical role in mucosal homeostasis and disease progression. Visual abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/648856v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@10fc2eaorg.highwire.dtl.DTLVardef@1c5b82corg.highwire.dtl.DTLVardef@1be747dorg.highwire.dtl.DTLVardef@d1d722_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2024

ALS-associated RNA binding proteins converge on UNC13A transcription through regulation of REST

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the selective loss of motor neurons. Although multiple pathophysiological mechanisms have been identified, a unified molecular basis for ALS has remained elusive. The ALS-associated RNA binding protein (RBP) TDP-43 has previously been shown to stabilize UNC13A mRNA by preventing cryptic exon inclusion. We here show that three ALS-associated RBPs--MATR3, FUS, and hnRNPA1--regulate UNC13A expression by targeting the silencing transcription factor REST. These three RBPs bind to and downregulate REST mRNA and thereby promote UNC13A transcription. REST overexpression was detected not only in response to the loss of each of these three RBPs in cultured cells but also in motor neurons of individuals with familial or sporadic ALS. The functional convergence of four RBPs on the regulation of UNC13A, a gene essential for synaptic transmission, highlights a pivotal contribution of these proteins to maitainance of synaptic integrity. Our findings thus provide key insight into ALS pathogenesis and a basis for the development of new therapeutic agents.

neuroscience↗

bioRxiv2024

Diversity and evolution of Radiolaria: Beyond the stars of the ocean

Since Ernst Haeckel and the Challenger expedition (1872-1876), Radiolaria have been known as ubiquitous and abundant star-shaped oceanic plankton. Their exquisite biomineralized skeletons have left an extensive fossil record which is extremely valuable for biostratigraphic and paleo-environmental research. In contemporary oceans, there is growing evidence that Radiolaria are significant contributors to marine food webs and global biogeochemical cycles. Here we provide a comprehensive morpho-molecular framework to assess the extant diversity, biogeography and evolutionary history of Radiolaria. Our analyses reveal that half of radiolarian diversity is morphologically undescribed, with a large part forming three hyper-diverse environmental clades, named Rad-A, Rad-B and Rad-C. We suggest that most of this undescribed diversity likely comprises skeleton-less life forms or endosymbionts, explaining their elusive nature. Phylogenetic analyses highlight the need for major revision of high-level Radiolaria taxonomy, including placement of the Collodaria within the order Nassellaria. Fossil calibration of a molecular clock revealed the first appearance of Radiolaria [~]760 million years ago (Ma), the development of the skeleton in the early Paleozoic ([~]500 Ma) and the onset of photosymbiotic relationships during the mid to late Mesozoic ([~]140 Ma), related to geological periods of oligotrophy and anoxia. The results presented here provide an extensive and robust framework for developing new perspectives on early eukaryotic diversification, paleo-environmental impacts on plankton evolution, and marine microbial ecology in rapidly evolving ecosystems.

evolutionary biology↗

bioRxiv2024

Harnessing Synaptic Vesicle Release and Recycling Mechanism for Molecule Delivery to Neurons

Neurodegenerative clinical trials often fail due to insufficient drug doses in reaching targeted cells and the unintended delivery to non-targeted cells. This study demonstrates an alternative neuron-selective drug delivery system, which utilizes the synaptic vesicle release and recycling mechanism (SVRM) by antibody shuttles targeting synaptic vesicle transmembrane proteins for molecule delivery. Using Synaptotagmin-2 (SYT2), we exemplify that intravenously administered anti-SYT2 antibodies localize to neuromuscular junctions, undergo uptake, and retrograde transport to ChAT-positive motor neurons (MNs) in the spinal cord and brainstem. The delivery of anti-microtubule agent and Malat1 gapmer antisense oligonucleotide to MNs with anti-SYT2 antibodies induces axon degeneration and reduction of Malat1 RNA expression, respectively. This approach circumvents the blood-spinal cord barrier, enabling selective delivery of therapeutic molecules to neurons while minimizing effects in non-targeted cells. Thus harnessing SVRM presents a promising strategy for enhancing drug concentrations in neurons and improving treatment efficacy for neurodegenerative diseases.

neuroscience↗

bioRxiv2024

Integrating Phenomic Selection Using Single-Kernel Near-Infrared Spectroscopy and Genomic Selection for Corn Breeding Improvement

Phenomic Selection (PS) is a cost-effective method proposed for predicting complex traits and enhancing genetic gain in breeding programs. The statistical procedures are similar to those utilized in genomic selection (GS) models, but molecular markers data are replaced with phenomic data, such as near-infrared spectroscopy (NIRS). However, the use of NIRS applied to PS typically utilized destructive sampling or collected data after the establishment of selection experiments in the field. Here, we explored the application of PS using non-destructive, single-kernel NIRS in a sweet corn breeding program, focusing on predicting future, unobserved field-based traits of economic importance, including ear and vegetative traits. Three models were employed on a diversity panel: G-BLUP and P-BLUP models, which used relationship matrices based on SNP and NIRS data, and a combined model. The genomic relationship matrices were evaluated with varying numbers of SNPs. Additionally, the P-BLUP model trained on the diversity panel was used to select doubled haploid (DH) lines for germination before planting, with predictions validated using observed data. The findings indicate that PS generated good predictive ability (e.g., 0.46 for plant height) and effectively distinguished between high and low germination rates in untested DH lines. Although GS generally outperformed PS, the model combining both information yielded the highest predictive ability, with considerably higher accuracies than GS when low marker densities were used. This study highlights the potential of NIRS both to achieve genetic gain where GS may not be feasible and to maintain/improve accuracy with SNP-based information while reducing genotyping costs. Key messagePhenomic selection using whole seeds is a promising alternative to improve genetic gain and complement genomic selection in corn breeding. Models that combine genomic and phenomic data maximize the predictive ability.

genetics↗

bioRxiv2024

PDPN/CLEC-2 axis modulates megakaryocyte subtypes in a hematopoietic stem cell-regulating megakaryocyte-dominant manner

IntroductionMegakaryocytes are classified into several subtypes including LSP1-positive immune-skewed, MYLK4-positive hematopoietic stem cell (HSC)-regulating, and BMAL1-positive platelet-producing megakaryocytes. Podoplanin (PDPN)-expressing stromal cells generate a microenvironment that promotes megakaryopoiesis in the bone marrow. In this context, PDPN interacts with C-type lectin-like receptor-2 (CLEC-2) on megakaryocyte progenitors, which induces megakaryocyte proliferation. However, the megakaryocyte subtypes developed by the regulation of the PDPN/CLEC-2 axis have not yet been elucidated. Materials and MethodsWe established an immortalized bone marrow PDPN-expressing stromal cell line and a PDPN-knockout line (PDPN WT and KO feeder cells, respectively). Bone marrow hematopoietic progenitors were committed to megakaryocytes in co-culture with PDPN WT or KO feeder cells. The number and ploidy of megakaryocytes, resultant platelets, and the polarization of megakaryocyte subtypes were investigated. ResultsThe number of megakaryocytes was significantly increased in the co-culture with PDPN WT feeder cells compared to that with PDPN KO feeder cells. The megakaryocytes on the PDPN WT and KO feeders showed their main ploidy at 16N[~]32N and 8N[~]16N, respectively. The number of platelets decreased in the co-culture with the PDPN WT feeder compared to those in the co-culture with the PDPN KO feeder. Megakaryocyte subtypes were immunocytochemically detected in in vitro differentiated CD41-positive megakaryocytes. For each megakaryocyte subtype, the percentage of MYLK4-positive megakaryocytes significantly increased and the percentage of BMAL1-positive megakaryocytes significantly decreased when co-cultured with the PDPN WT feeder. ConclusionThe PDPN/CLEC-2 axis modulates megakaryocyte subtype differentiation, with a predominance of HSC-regulating megakaryocytes.

cell biology↗

bioRxiv2024

Tissue growth associated transition of podoplanin-expressing stromal cells in the postnatal mouse femur

In vertebral long bones, such as the femur, bone formation involves endochondral ossification. Endochondral ossification first occurs in the central region of the fetal diaphysis, the primary ossification center. Podoplanin (PDPN) is a transmembrane mucin-like glycoprotein, and PDPN-positive cells play key roles in various organ/tissue development. In adult mice, osteolineage PDPN-positive cells are associated with femoral microarchitecture. However, specific roles of PDPN in fetal bone development remain unclear. Therefore, in this study, we aimed to investigate the spatiotemporal dynamics and physiological functions of PDPN-positive cells during fetal femur development. In the fetal femur, PDPN-positive cells first emerged in the primitive cortical bone, termed the bone collar, concurrently with primary ossification center initiation. Several PDPN-positive cells in the bone collar migrated to the marrow cavity and populated the metaphyseal trabecular bone. Most PDPN-positive cells in both the bone collar and trabeculae exhibited osteolineage features, such as osterix expression. Pdpn knockout fetuses exhibited abnormal recruitment of osterix-positive cells and mineral deposition in the dorsal bone collar. Overall, our results suggest that PDPN-positive cells constitute a spatially regulated osteolineage population that contributes to coordinated fetal femur development.

cell biology↗

bioRxiv2024

Erythropoietin production in embryonic neural cells is controlled by hypoxia-inducible factors and histone deacetylases in an undifferentiated state

During mammalian development, production sites of the erythroid growth factor erythropoietin (EPO) shift from the neural tissues to the liver in embryos and to the adult kidneys. Embryonic neural EPO-producing (NEP) cells, a subpopulation of neuroepithelial and neural crest cells, express the Epo gene between embryonic day (E) 8.5 and E11.5 to promote primitive erythropoiesis in mice. While Epo gene expression in the liver and kidney is induced under hypoxic conditions through hypoxia-inducible transcription factor (HIF) 2, the Epo gene regulatory mechanisms in NEP cells remain to be elucidated. This study confirms the presence of cells coexpressing the genes encoding EPO and HIF2 in E9.5 neural tubes, where the hypoxic microenvironment activates HIF1. In human neural progenitors and mouse embryonic neural tissues, a HIF-activating compound upregulated EPO expression, and this induction was blocked by inhibiting HIFs. Additionally, a cell line of NEP cell derivatives that no longer expressed the Epo gene demonstrated that histone deacetylase inhibitors (HDACIs) reactivate EPO production while rejuvenating the cells. HDACIs also induced EPO gene expression in SK-N-BE(2)c human neuroblastoma cells and mouse primary neural crest cells. Thus, EPO production is controlled by epigenetic mechanisms and hypoxia signaling in an immature state of hypoxic NEP cells.

molecular biology↗