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Ito, K.

Publications and source records attributed to Ito, K..

At least 55 records · Page 3Linked to original sources

Mouse-Geneformer: A Deep Learning Model for Mouse Single-Cell Transcriptome and Its Cross-Species Utility

Deep learning techniques are increasingly utilized to analyze large-scale single-cell RNA sequencing (scRNA-seq) data, offering valuable insights from complex transcriptome datasets. Geneformer, a pre-trained model using a Transformer Encoder architecture and human scRNA-seq datasets, has demonstrated remarkable success in human transcriptome analysis. However, given the prominence of the mouse, Mus musculus, as a primary mammalian model in biological and medical research, there is an acute need for a mouse-specific version of Geneformer. In this study, we developed a mouse-specific Geneformer (mouse-Geneformer) by constructing a large transcriptome dataset consisting of 21 million mouse scRNA-seq profiles and pre-training Geneformer on this dataset. The mouse-Geneformer effectively models the mouse transcriptome and, upon fine-tuning for downstream tasks, enhances the accuracy of cell type classification. In silico perturbation experiments using mouse-Geneformer successfully identified disease-causing genes that have been validated in in vivo experiments. These results demonstrate the feasibility of analyzing mouse data with mouse-Geneformer and highlight the robustness of the Geneformer architecture, applicable to any species with large-scale transcriptome data available. Furthermore, we found that mouse-Geneformer can analyze human transcriptome data in a cross-species manner. After the ortholog-based gene name conversion, the analysis of human scRNA-seq data using mouse-Geneformer, followed by fine-tuning with human data, achieved cell type classification accuracy comparable to that obtained using the original human Geneformer. In in silico simulation experiments using human disease models, we obtained results similar to human-Geneformer for the myocardial infarction model but only partially consistent results for the COVID-19 model, a trait unique to humans (laboratory mice are not susceptible to SARS-CoV-2). These findings suggest the potential for cross-species application of the Geneformer model while emphasizing the importance of species-specific models for capturing the full complexity of disease mechanisms. Despite the existence of the original Geneformer tailored for humans, human research could benefit from mouse-Geneformer due to its inclusion of samples that are ethically or technically inaccessible for humans, such as embryonic tissues and certain disease models. Additionally, this cross-species approach indicates potential use for non-model organisms, where obtaining large-scale single-cell transcriptome data is challenging. Author SummaryResearchers have developed Geneformer, a powerful tool that utilizes advanced deep learning techniques and large-scale single-cell transcriptome data to analyze human cell genetic activity. However, given the extensive use of mice (Mus musculus) in medical and biology research, there is a need for a similar tool tailored to this model organism. To address this gap, we developed mouse-Geneformer, an adaptation of Geneformer trained on a large dataset of mouse single-cell RNA sequencing data obtained from 20 million cells. Mouse-Geneformer demonstrates high accuracy in identifying distinct cell types and predicting disease-causing genes in gene manipulation simulation experiments. Moreover, mouse-Geneformer exhibited comparable accuracy to the original human Geneformer, even when applied to human cell data, suggesting its potential for cross-species use. For instance, it performed well in studying heart disease but was less consistent with COVID-19, likely due to the differences between species in how they react to the virus. Overall, mouse-Geneformer could be a valuable resource for studying not only mice but also other animals, especially when large-scale data are challenging to obtain. Furthermore, this cross-species approach may probe beneficial in human research, especially for tissues that are difficult to access, such as embryonic samples.

bioinformatics↗

Transcriptomic dynamics of petal development in the one-day flower species, Japanese morning glory (Ipomoea nil)

Various aspects of Japanese morning glory (Ipomoea nil) petals, such as color, pattern, shape, flower opening time, and senescence, have been extensively studied. To facilitate such studies, transcriptome data were collected from flower petals at 3-h intervals over 3.5 days; the data was collected from 72 h before and 12 h after flower opening, accounting for 29 timepoints. Data analysis revealed substantial transcriptomic changes before and after flower opening. The expression patterns of cell division marker genes indicated that cell division practically stops at approximately 48 h before flower opening. Furthermore, the increased expression of genes encoding transporters for sugars, amino acids, nucleic acids, and autophagy-related genes was observed after flower opening, indicating the translocation of nutrients from senescing petal cells to other developing tissues. Correlations were found between the temporal expression patterns of the three transcriptional regulators and expression patterns of different sets of structural genes within the anthocyanin biosynthesis pathway, indicating differential reliance on each regulator for the activation of specific structural genes. Furthermore, clock genes were identified. Three copies of the clock gene ELF3 did not exhibit circadian rhythms, potentially allowing I. nil to adapt to high-latitude regions. The temporal transcriptome data and interactive database (https://ipomoeanil.nibb.ac.jp/fpkm/) offer valuable insights into gene expression dynamics, periodicity, and correlations and provide a crucial resource for further research on I. nil and other plant species.

plant biology↗

C-C chemokine receptor 4 deficiency exacerbates early atherosclerosis in mice

Chronic inflammation via dysregulation of T cell immune responses is critically involved in the pathogenesis of atherosclerotic cardiovascular disease. Improving the balance between proinflammatory T cells and anti-inflammatory regulatory T cells (Tregs) may be an attractive approach for treating atherosclerosis. Although C-C chemokine receptor 4 (CCR4) has been shown to mediate the recruitment of T cells to inflamed tissues, its role in atherosclerosis is unclear. Here, we show that genetic deletion of CCR4 in hypercholesterolemic mice accelerates the development of early atherosclerotic lesions characterized by an inflammatory plaque phenotype. This was associated with the augmentation of proinflammatory T helper type 1 (Th1) cell responses in peripheral lymphoid tissues, para-aortic lymph nodes, and atherosclerotic aorta. Mechanistically, CCR4 deficiency in Tregs impaired their suppressive function and tended to inhibit their migration to the atherosclerotic aorta, and subsequently augmented Th1 cell-mediated immune responses through defective regulation of dendritic cell function, which accelerated aortic inflammation and atherosclerotic lesion development. Thus, we revealed a previously unrecognized role for CCR4 in controlling the early stage of atherosclerosis via Treg-dependent regulation of proinflammatory T cell responses. Our data suggest that CCR4 is an important negative regulator of atherosclerosis.

immunology↗

A STAT3 Degrader Demonstrates Pre-clinical Efficacy in Venetoclax resistant Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy that continues to have poor prognosis despite recent therapeutic advances. Venetoclax (Ven), a BCL2-inhibitor has shown a high response rate in AML; however, relapse is invariable due to mitochondrial dysregulation that includes upregulation of the antiapoptotic protein MCL1, a central mechanism of Ven resistance (Ven-res). We have previously demonstrated that the transcription factor STAT3 is upregulated in AML hematopoietic stem and progenitor cells (HSPCs) and can be effectively targeted to induce apoptosis of these aberrant cells. We now show that overexpression of STAT3 alone is sufficient to initiate a strong AML phenotype in a transgenic murine model. Phospho-proteomic data from Ven treated AML patients show a strong correlation of high total STAT3 and phospho-STAT3 [both p-STAT3(Y705) and p-STAT3(S727)] expression with worse survival and reduced remission duration. Additionally, significant upregulation of STAT3 was observed in Ven-res cell lines, in vivo models and primary patient samples. A novel and specific degrader of STAT3 demonstrated targeted reduction of total STAT3 and resulting inhibition of its active p-STAT3(Y705) and p-STAT3(S727) forms. Treatment with the STAT3 degrader induced apoptosis in parental and Ven-res AML cell lines and decreased mitochondrial depolarisation, and thereby dependency on MCL1 in Ven-res AML cell line, as observed by BH3 profiling assay. STAT3 degrader treatment also enhanced differentiation of myeloid and erythroid colonies in Ven-res peripheral blood mononuclear cells (PBMNCs). Upregulation of p-STAT3(S727) was also associated with pronounced mitochondrial structural and functional dysfunction in Ven-res cell lines, that were restored by STAT3 degradation. Treatment with a clinical-stage STAT3 degrader, KT-333 resulted in a significant reduction in STAT3 and MCL1 protein levels within two weeks of treatment in a cell derived xenograft model of Ven-res AML. Additionally, this treatment significant improvement in the survival of a Ven-res patient-derived xenograft in-vivo study. Degradation of STAT3 resulting in downregulation of MCL1 and improvements in global mitochondrial dysfunction suggests a novel mechanism of overcoming Ven-res in AML. Statement of PurposeFive-year survival from AML is dismal at 30%. Our prior research demonstrated STAT3 over-expression in AML HSPCs to be associated with inferior survival. We now explore STAT3 over-expression in Ven-res AML, explain STAT3 mediated mitochondrial perturbations and describe a novel therapeutic strategy, STAT3 degradation to overcome Ven-res.

cancer biology↗

The Calmodulin-like proteins, CML13 and CML14 Function as Myosin Light Chains for the Class XI Myosins in Arabidopsis

Myosins are a crucial motor protein associated with the actin cytoskeleton in eukaryotic cells. Structurally, myosins form heteromeric complexes, with smaller light chains such as calmodulin (CaM) bound to isoleucine-glutamine (IQ) domains in the neck region. These interactions facilitate mechano-enzymatic activity. Recently, we identified Arabidopsis CaM-like (CML) proteins CML13 and CML14 as interactors with proteins containing multiple IQ domains, that function as the myosin VIII light chains. This study demonstrates that CaM, CML13, and CML14 specifically bind to the neck region of all 13 Arabidopsis myosin XI isoforms, with some preference among the CaM/CML-IQ domains. Additionally, we observed distinct residue preferences within the IQ domains for CML13, CML14, and CaM. In vitro experiments revealed that recombinant CaM, CML13, and CML14 exhibit calcium-independent binding to the IQ domains of myosin XIs. Furthermore, when co-expressed with MAP65-1-myosin fusion proteins containing the IQ domains of myosin XIs, CaM, CML13, and CML14 co-localize to microtubules. In vitro actin motility assays demonstrated that recombinant CML13, CML14, and CaM function as myosin XI light chains. A cml13 T-DNA mutant exhibited a shortened primary root phenotype that was complemented by the wild-type CML13 and was similar to that observed in a triple myosin XI mutant (xi3KO). Overall, our data indicate that Arabidopsis CML13 and CML14 are novel myosin XI light chains that likely participate in a breadth of myosin XI functions. HighlightMyosin XI proteins play a crucial role in the plant cytoskeleton, but their associated light chains have remained unidentified. Here, we show that calmodulin-like proteins, CML13 and CML14, serve as light chains for myosin XI, similar to their role for myosin VIII proteins

plant biology↗

Comparative genomic analysis of Latilactobacillus sakei strains provides new insights into their association with different niche adaptations

Latilactobacillus sakei, a lactic acid bacterium in diverse environments such as fermented foods, meat, and the human gastrointestinal tract, exhibits significant genetic diversity and niche-specific adaptations. This study conducts a comprehensive comparative genomic analysis of 30 complete L. sakei genomes to uncover the genetic mechanisms underlying these adaptations. Phylogenetic analysis divided the species into three distinct clades that did not correlate with the source of isolation and did not suggest any niche-specific evolutionary direction. The pan-genome analysis revealed a substantial core genome alongside a diverse genetic repertoire, indicating both high genetic conservation and adaptability. Predicted growth rates based on codon use bias analysis suggest that L. sakei strains have an overall faster growth rate and may be able to efficiently dominant in competitive environments. Plasmid analysis revealed a variety of plasmids carrying genes essential for carbohydrate metabolism, enhancing L. sakeis ability to thrive in various fermentation substrates. It was also found that the number of genes belonging to the GH1 family among sugar metabolism-related genes present on chromosomes and plasmids varies between strains, and that AA1, which is involved in alcohol oxidation, has been acquired from plasmids. BLAST analysis revealed that some strains have environmental adaptation gene clusters of cell surface polysaccharides that may mediate attachment to food and mucosa. These findings not only underscore the genetic and functional diversity of L. sakei but also highlight its potential as a potent starter culture in fermentation and as a probiotic. The knowledge gleaned from this study lays a solid foundation for future research aimed at harnessing the genetic traits of L. sakei strains for industrial and health-related applications.

microbiology↗

From Soil to Surface: Green Infrastructure Enhances Microbial Communities in the Built Environment

High microbial diversity offers extensive benefits to both the environment and human health, contributing to ecosystem stability, nutrient cycling, and pathogen suppression. In built environments, factors such as building design, human activity, and cleaning protocols influence microbial communities. This study investigates the impact of landscape design on microbial diversity and function within the "Visionary Lab" exhibition in Tokyo, Japan, using 16S rRNA gene amplicon sequencing and shallow shotgun sequencing. Despite the limited sample size, the study suggests that the Visionary Lab samples may exhibit higher microbial diversity compared to other museum areas. Potential distinct microbial community structures may be correlated with sampling locations. However, despite this, no consistent patterns were observed in virulence factors or antimicrobial resistance genes across the samples. Metabolic function analysis showed varied profiles, suggesting diverse ecological interactions influenced that may be by the curated landscape. This suggest that the curated landscape design may have the potential to enhance microbial diversity, highlighting a possible avenue to create healthier and more sustainable built environments. However, the lack of consistent patterns in virulence factors and antimicrobial resistance genes underscores the complexity of microbial community dynamics.

microbiology↗

Cellulose Rich Food Leads Anxiety through Gut-Brain Axis-mediated Amygdalar Dopamine Upregulation.

It is widely said that healthy intestinal environment takes essential role for better mental condition. One of the known dietary nutrients which maintains intestinal environment is the dietary fiber. Recent study showed that maintaining intestinal environment by dietary fiber succeeded to alleviate the psychiatric disorder symptoms in animals. However, such effects have only been reported with soluble fiber, which is highly fermentable and promotes short-chain fatty acid (SCFA) production, and not with insoluble fiber. Therefore, we aimed to verify whether insoluble fiber, such as cellulose, can alter emotion via changes in the gut. We divided mice into two groups and fed either standard diet (SD, contains both insoluble and soluble dietary fibers) or cellulose rich diet (CRD, contains cellulose alone as the dietary fibers). The CRD-fed mice displayed 1) the increased the anxiety-like behavior accompanied with 2) the modified amygdalar dopamine signaling. We further found the decreased intestinal SCFA levels along with intestinal permeability, dysmotility and hypersensitivity in CRD-fed mice. These behavioral and physiological effect of CRD has been completely abolished in vagotomized mice, indicating the direct link between intestinal environment exacerbation to the emotion through gut-brain axis. Additionally, the opioid antagonist abolished the CRD-induced anxiety, suggesting the involvement of opioidergic system to the anxiety which may evoked by increased amygdalar dopamine levels. Altogether, our findings suggest that consumption of cellulose alone as the dietary fiber may evoke intestinal abnormalities which fires the vagus nerve then opiodergic system and amygdalar dopamine upregulation, resulting in the enhancement of anxiety. Graphical Abstract: Possible mechanism of CRD-induced anxiety unveiled by current studyOur study clarified that long-consumption of cellulose-rich food (CRD) will lead decrease of SCFAs which may cause the intestinal disability, including decreased motility and increased intestinal permeability as well as upregulation of TRPA1 and SGLT1. These physiological modifications resulted as the intestinal hypersensitivity, which possibly overstimulate the vagal transmission which may activate endogenous opioidergic systems such as enkephalin (Enk) at the nucleus tractus solitarii (NTS). The activation of opioidergic system may suppress the GABAergic neuron in ventral tegmental area (VTA), resulting in the excess release of dopamine and further receptor modification in amygdala (Amyg), which might in the end cause the characteristic anxiety. The figure was created with BioRender.com. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/593082v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@1a0c4aborg.highwire.dtl.DTLVardef@1cfefceorg.highwire.dtl.DTLVardef@88cfc0org.highwire.dtl.DTLVardef@1ff5b0a_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

Bioinformatic evaluation of the potential oral-gut translocation of periodontal pathogens in patients with colorectal polyps

ObjectiveThis study aimed to characterize the profiles of the oral and gut microbiota of patients with colorectal polyps using 16S rRNA gene sequencing and bioinformatic approaches. BackgroundPrevious studies have shown microbial translocation from the oral cavity to the gut, implying pathogenic impacts on gastroesophageal disease, including colorectal cancer (CRC). However, its details remain unclear. MethodsTwenty patients scheduled for endoscopic colorectal polypectomy were enrolled in this study. Oral samples (saliva and subgingival dental plaque) and intestinal samples (feces and swab of intestinal mucosa) were collected during preoperative and 6-month-postoperative reassessment periods. After sequencing the V3-V4 region of the bacterial 16S rRNA gene, several bioinformatic analyses (bacterial composition, diversity, core microbiome, and shared ASV) were performed on pre- and postoperative samples for each subject. ResultsThe bacterial composition was dominated by Bacteroides, Streptococcus, Fusobacterium, Veillonella, and Prevotella_7 in all four samples. Beta diversity analysis using weighted UniFrac distance distinctly segregated the samples between oral and intestinal environments in the principal coordinate analysis plot. Core microbiome analysis revealed that Streptococcus and Porphyromonas were dominantly shared in intra-oral environments. Additionally, alongside Streptococcus, periodontitis-related bacteria, such as Veillonella, Fusobacterium, Porphyromonas, Prevotella_7, Haemophilus, and Prevotella, were identified as shared genera between oral and intestinal environments. Finally, shared ASV analysis demonstrated that Streptococcus was shared in the oral and intestinal environments of most patients, while periodontal pathogens were shared in some patients. ConclusionsThe core microbiome and shared ASV analyses revealed that several genes are shared between oral and intestinal environments in patients with colorectal polyps, indicating the oral-gut translocation of periodontitis-related bacteria. Further large-scale studies are needed to elucidate their involvement in CRC.

bioinformatics↗

Comparative analysis based on shared amplicon sequence variants reveals that cohabitation influences gut microbiota sharing between humans and dogs

IntroductionThe One Health concept is a comprehensive understanding of the interaction between humans, animals, and the environment. The cohabitation of humans and dogs positively affects their physical, mental, and social well-being. It is recognized as an essential factor from the One Health perspective. Furthermore, a healthy balance in the gut microbiome is essential for good health, and the sharing of gut microbes between humans and dogs may positively impact the health of both hosts. Therefore, elucidating the sharing of gut bacteria between humans and dogs is important for understanding One Health. However, most studies have examined sharing at the taxonomic level, and it remains unclear whether the same bacteria are transferred between humans and dogs, and whether they mutually influence each other. MethodsHere, microbiome analysis and 16S rRNA gene amplicon sequence variant (ASV) analysis was performed to address this question. Results16S rRNA gene ASVs analysis indicated that gut microbes have been transferred between humans and dogs. The overall structure of the gut microbiota within human-dog pairs remained unchanged after three months of adaptation. However, some ASVs were shared within human-dog pairs. Many shared ASVs were highly abundant within each host, and this high abundance may be considered a factor that influences bacterial transfer between hosts. DiscussionOur results demonstrate the possibility of the direct transfer of gut bacteria between humans and dogs, providing an important insight for achieving good health through human-dog cohabitation.

microbiology↗

Myc upregulates Ggct, γ-glutamylcyclotransferase to promote development of p53-deficient osteosarcoma

Osteosarcoma (OS) in humans is characterized by alterations in the TP53 gene. In mice, loss of p53 triggers OS development, for which c-Myc (Myc) oncogenicity is indispensable. However, little is known about which genes are targeted by Myc to promote tumorigenesis. Here, we examined the role of Ggct, {gamma}-glutamylcyclotransferase which is a component enzyme of {gamma}-glutamyl cycle essential for glutathione homeostasis, in human and mouse OS development. We found that GGCT is a poor prognostic factor for human OS, and that deletion of Ggct suppresses p53-deficient osteosarcomagenesis in mice. Myc upregulates Ggct directly by binding to the Ggct promoter, and deletion of a Myc binding site therein by genome editing attenuated the tumorigenic potential of p53- deficient OS cells. Taken together, these results show a rationale that GGCT is widely upregulated in cancer cells and solidify its suitability as a target for anticancer drugs.

cancer biology↗

Impact of rice GENERAL REGULATORY FACTOR14h (GF14h) on low-temperature seed germination and its application to breeding

Direct seeding is employed to circumvent the labor-intensive process of rice (Oryza sativa) transplantation, but this approach requires varieties with vigorous low-temperature germination (LTG) when sown in cold climates. To investigate the genetic basis of LTG, we identified the quantitative trait locus (QTL) qLTG11 from rice variety Arroz da Terra, which shows rapid seed germination at lower temperatures, using QTL-seq. We delineated the candidate region to a 52-kb interval containing GENERAL REGULATORY FACTOR14h (GF14h) gene, which is expressed during seed germination. The Arroz da Terra GF14h allele encodes functional GF14h, whereas Japanese rice variety Hitomebore harbors a 4-bp deletion in the coding region. Knocking out functional GF14h in a near-isogenic line (NIL) carrying the Arroz da Terra allele decreased LTG, whereas overexpressing functional GF14h in Hitomebore increased LTG, indicating that GF14h is the causal gene behind qLTG11. Analysis of numerous Japanese rice accessions revealed that the functional GF14h allele was lost from popular varieties during modern breeding. We generated a NIL in the Hitomebore background carrying a 172-kb genomic fragment from Arroz da Terra including GF14h. The NIL showed superior LTG compared to Hitomebore, with otherwise comparable agronomic traits. The functional GF14h allele from Arroz da Terra represents a valuable resource for direct seeding in cold regions. Author SummaryRice serves as a fundamental crop sustaining over half of the global population. With the rapid growth of the worlds population, it will become increasingly important to improve rice productivity. On the other hand, the aging of rice farmers in Japan has resulted in a constant labor shortage. To address this, direct seeding, in which seeds are sown directly in rice fields without going through the most labor-intensive part of the rice cultivation process, i.e., seedling production and transplanting, has been recommended. However, prevalent elite rice varieties are known to be unsuitable for direct seeding due to their poor seed germination ability under low-temperature conditions. In this study, we show for the first time that GF14h gene from the Portuguese variety Arroz da Terra improves seed germination at low temperatures (LTG). In addition, a novel cross-bred line was generated by introducing the GF14h-containing genomic segment from Arroz da Terra into Hitomebore, a widely cultivated variety in northern Japan. This line is expected to be used as a pre-breeding material to enhance LTG. This study will provide a genetic basis for LTG and contribute to basic and applied research progress.

plant biology↗

The similarities in microbial and chemical patterns of fermentation in two open environments were promoted by using 150-year-old Nukadoko as starters.

Nukadoko, a fermented rice bran employed in traditional Japanese pickling, uses lactic acid bacteria to ferment vegetables. Here, we report the microbial and chemical data of a mixture of matured 150-year-old nukadoko and commercially available rice bran placed in two open environments over 29 days. Across the two environments, Loigolactobacillus was identified as the dominant microbial genera in the later stages of fermentation in nukadoko. The period of increase in the relative abundance of Loigolactobacillus correlated with a decrease in pH and Oxidation-Reduction Potential (ORP) values. While the two environments showed a difference in the rate of change in microbial diversity, they shared the common process through which Loigolactobacillus outcompeted adventitious bacteria in nukadoko, as indicated by the alpha and beta diversity index. Thus, the similarities in microbial and chemical data across two open environments during fermentation using starters indicate that starters contribute to the stability of fermentation in open environments.

microbiology↗

Synaptic plasticity in the medial preoptic area of male mice encodes social experiences with female and regulates behavior toward young

A dramatic shift from aggressive infanticidal to paternal behaviors is an essential event for male mice after mating. While the central part of the medial preoptic area (cMPOA) has been shown to critically mediate the paternal behaviors in mice, how this brain region becomes activated by mating and subsequent interaction with pups has not been investigated. Here, we demonstrate that the reduction in inhibitory synaptic strength towards the cMPOA provided by posterior-dorsal medial amygdala (MePD) neurons is a key event for the post-mating behavioral shift in males. Consistent with this, we found optogenetic disinhibition of MeCartpt to the cMPOA synapses reduces male aggression towards pups. The cMPOA of paternal mice mediated pup-induced neural plastic changes in the bed nucleus of the stria terminalis. These findings provide possible functions of cMPOA neural circuits required for the reception to young in male mice.

zoology↗

Culture system for longitudinal monitoring of bone remodeling ex vivo

To quantify and visualize both bone formation and resorption within osteochondral explants cultured ex vivo is challenging with the current analysis techniques. An approach that enables monitoring of bone remodeling dynamics is longitudinal micro-computed tomography ({micro}CT), a non-destructive technique that relies on repeated {micro}CT scanning and subsequent registration of consecutive scans. In this study, a two-compartment culture system suitable for osteochondral explants that allowed for {micro}CT scanning during ex vivo culture was established. Explants were scanned repeatedly in a fixed orientation, which allowed assessment of bone remodeling due to adequate image registration. Using this method, bone formation was found to be restricted to the outer surfaces when cultured statically. To demonstrate that the culture system could capture differences in bone remodeling, explants were cultured statically and under dynamic compression as loading promotes osteogenesis. No quantitative differences between static and dynamic culture were revealed. Still, only in dynamic conditions, bone formation was visualized on trabecular surfaces located within the inner cores, suggesting enhanced bone formation towards the center of the explants upon mechanical loading. Taken together, the ex vivo culture system in combination with longitudinal {micro}CT scanning and subsequent registration of images demonstrated potential for evaluating bone remodeling within explants.

bioengineering↗

Integration of Osteoclastogenesis through addition of PBMCs in Human Osteochondral Explants cultured Ex vivo

The preservation of tissue specific cells in their native 3D extracellular matrix in bone explants provides a unique platform to study remodeling. Thus far, studies involving bone explant cultures showed a clear focus on achieving bone formation and neglected osteoclast activity and resorption. To simulate the homeostatic bone environment ex vivo, both key elements of bone remodeling need to be represented. This study aimed to assess and include osteoclastogenesis in human osteochondral explants through medium supplementation with RANKL and M-CSF and addition of peripheral blood mononuclear cells (PBMCs), providing osteoclast precursors. Osteochondral explants were freshly harvested from human femoral heads obtained from hip surgeries and cultured for 20 days in a two-compartment culture system. Osteochondral explants preserved viability and cellular abundance over the culture period, but histology demonstrated that resident osteoclasts were no longer present after 4 days of culture. Quantitative extracellular tartrate resistant acid phosphatase (TRAP) analysis confirmed depletion of osteoclast activity on day 4 even when stimulated with RANKL and M-CSF. Upon addition of PBMCs, a significant upregulation of TRAP activity was measured from day 10 onwards. Evaluation of bone loss trough {micro}CT registration and measurement of extracellular cathepsin K activity revealed indications of enhanced resorption upon addition of PBMCs. Based on the results we suggest that an external source of osteoclast precursors, such as PBMCs, needs to be added in long-term bone explant cultures to maintain osteoclastic activity, and bone remodeling. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/552563v1_ufig1.gif" ALT="Figure 1"> View larger version (16K): org.highwire.dtl.DTLVardef@b3df30org.highwire.dtl.DTLVardef@101d1e7org.highwire.dtl.DTLVardef@7bc56borg.highwire.dtl.DTLVardef@1de2d7e_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

Group comparison based on genetic information reveals lineage-specific therapeutic vulnerabilities in acute myeloid leukemia

Cancer is a genetic disease with specific mutations or fusions. Therapies targeting cancer cell-specific essential genes are expected to have efficient anticancer effects with fewer side effects. To explore such cancer cell-specific vulnerabilities, we established a two-group comparison system to predict essential genes in each cancer subtype using the data from the Cancer Dependency Map (DepMap). We applied this analytical method to acute myeloid leukemia (AML) and identified PCYT1A and BCL2L1 as a specific vulnerability in MLL-rearranged AML and TP53-mutated AML, respectively. Interestingly, further investigation revealed that PCYT1A is in fact a critical regulator in monocytic AML including those with MLL-rearrangements, and BCL2L1 is essential in acute erythroid leukemia in which TP53 is frequently mutated. These results highlighted the importance of cell of origin, rather than the genetic aberrations alone, to identify subtype-specific vulnerabilities in AML. The DepMap-based two-group comparison approach could accelerate the discovery of subtype-specific therapeutic targets in diverse cancers.

cancer biology↗

Phylogeographical evidence for historical long-distance dispersal in the flightless stick insect Ramulus mikado

Exploring how organisms overcome geographical barriers to dispersal is a fundamental question in biology. Passive long-distance dispersal events, although infrequent and unpredictable, have a considerable impact on species range expansions. Despite limited active dispersal capabilities, many stick insect species have vast geographical ranges, indicating that passive long-distance dispersal is vital for their distribution. A potential mode of passive dispersal in stick insects is via the egg stage within avian digestive tracts, as suggested by experimental evidence. However, detecting such events under natural conditions is challenging due to their rarity. To indirectly assess the importance of historical avian-mediated dispersal, we examined the population genetic structure of the flightless stick insect Ramulus mikado based on a multifaceted molecular approach (COI haplotypes, nuclear SSR markers, and genome-wide SNPs). Subsequently, we identified unique phylogeographic patterns, including the discovery of identical COI genotypes spanning considerable distances, which substantiates the notion of passive long-distance genotypic dispersal. Overall, all the molecular data revealed low and mostly non-significant genetic differentiation among populations, with identical or very similar genotypes across distant populations. We propose that long-distance dispersal facilitated by birds is the most plausible explanation for the unique phylogeographic pattern observed in this flightless stick insect.

evolutionary biology↗