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Nature Communications Jun 2024Although our understanding of the involvement of heterochromatin architectural factors in shaping nuclear organization is improving, there is still ongoing debate...
Although our understanding of the involvement of heterochromatin architectural factors in shaping nuclear organization is improving, there is still ongoing debate regarding the role of active genes in this process. In this study, we utilize publicly-available Micro-C data from mouse embryonic stem cells to investigate the relationship between gene transcription and 3D gene folding. Our analysis uncovers a nonmonotonic - globally positive - correlation between intragenic contact density and Pol II occupancy, independent of cohesin-based loop extrusion. Through the development of a biophysical model integrating the role of transcription dynamics within a polymer model of chromosome organization, we demonstrate that Pol II-mediated attractive interactions with limited valency between transcribed regions yield quantitative predictions consistent with chromosome-conformation-capture and live-imaging experiments. Our work provides compelling evidence that transcriptional activity shapes the 4D genome through Pol II-mediated micro-compartmentalization.
Topics: Animals; Mice; Mouse Embryonic Stem Cells; Transcription, Genetic; RNA Polymerase II; Chromosomal Proteins, Non-Histone; Cohesins; Heterochromatin; Chromosomes; Chromatin; Cell Cycle Proteins; Gene Expression Regulation
PubMed: 38918438
DOI: 10.1038/s41467-024-49727-7 -
Nature Communications Jun 2024The development of haematopoiesis involves the coordinated action of numerous genes, some of which are implicated in haematological malignancies. However, the biological...
The development of haematopoiesis involves the coordinated action of numerous genes, some of which are implicated in haematological malignancies. However, the biological function of many genes remains elusive and unknown functional genes are likely to remain to be uncovered. Here, we report a previously uncharacterised gene in haematopoiesis, identified by screening mutant embryonic stem cells. The gene, 'attenuated haematopoietic development (Ahed)', encodes a nuclear protein. Conditional knockout (cKO) of Ahed results in anaemia from embryonic day 14.5 onward, leading to prenatal demise. Transplantation experiments demonstrate the incapacity of Ahed-deficient haematopoietic cells to reconstitute haematopoiesis in vivo. Employing a tamoxifen-inducible cKO model, we further reveal that Ahed deletion impairs the intrinsic capacity of haematopoietic cells in adult mice. Ahed deletion affects various pathways, and published databases present cancer patients with somatic mutations in Ahed. Collectively, our findings underscore the fundamental roles of Ahed in lifelong haematopoiesis, implicating its association with malignancies.
Topics: Animals; Hematopoiesis; Mice; Mice, Knockout; Humans; Female; Hematopoietic Stem Cells; Mice, Inbred C57BL; Mutation; Anemia; Male; Embryonic Stem Cells
PubMed: 38918373
DOI: 10.1038/s41467-024-49252-7 -
Acta Neuropathologica Jun 2024Alzheimer's disease (AD) is the most common cause of dementia, and disease mechanisms are still not fully understood. Here, we explored pathological changes in human...
Xenografted human iPSC-derived neurons with the familial Alzheimer's disease APP mutation reveal dysregulated transcriptome signatures linked to synaptic function and implicate LINGO2 as a disease signaling mediator.
Alzheimer's disease (AD) is the most common cause of dementia, and disease mechanisms are still not fully understood. Here, we explored pathological changes in human induced pluripotent stem cell (iPSC)-derived neurons carrying the familial AD APP mutation after cell injection into the mouse forebrain. APP mutant iPSCs and isogenic controls were differentiated into neurons revealing enhanced Aβ production, elevated phospho-tau, and impaired neurite outgrowth in APP neurons. Two months after transplantation, APP and control neural cells showed robust engraftment but at 12 months post-injection, APP grafts were smaller and demonstrated impaired neurite outgrowth compared to controls, while plaque and tangle pathology were not seen. Single-nucleus RNA-sequencing of micro-dissected grafts, performed 2 months after cell injection, identified significantly altered transcriptome signatures in APP iPSC-derived neurons pointing towards dysregulated synaptic function and axon guidance. Interestingly, APP neurons showed an increased expression of genes, many of which are also upregulated in postmortem neurons of AD patients including the transmembrane protein LINGO2. Downregulation of LINGO2 in cultured APP neurons rescued neurite outgrowth deficits and reversed key AD-associated transcriptional changes related but not limited to synaptic function, apoptosis and cellular senescence. These results provide important insights into transcriptional dysregulation in xenografted APP neurons linked to synaptic function, and they indicate that LINGO2 may represent a potential therapeutic target in AD.
Topics: Humans; Induced Pluripotent Stem Cells; Alzheimer Disease; Neurons; Transcriptome; Animals; Amyloid beta-Protein Precursor; Mice; Nerve Tissue Proteins; Mutation; Membrane Proteins; Synapses; Amyloid beta-Peptides; Signal Transduction
PubMed: 38918213
DOI: 10.1007/s00401-024-02755-5 -
Cell Stem Cell Jun 2024Aging is the biggest risk factor for the development of Alzheimer's disease (AD). Here, we performed a whole-genome CRISPR screen to identify regulators of neuronal age...
Aging is the biggest risk factor for the development of Alzheimer's disease (AD). Here, we performed a whole-genome CRISPR screen to identify regulators of neuronal age and show that the neddylation pathway regulates both cellular age and AD neurodegeneration in a human stem cell model. Specifically, we demonstrate that blocking neddylation increased cellular hallmarks of aging and led to an increase in Tau aggregation and phosphorylation in neurons carrying the APP mutation. Aged APP but not isogenic control neurons also showed a progressive decrease in viability. Selective neuronal loss upon neddylation inhibition was similarly observed in other isogenic AD and in Parkinson's disease (PD) models, including PSEN cortical and LRRK2 midbrain dopamine neurons, respectively. This study indicates that cellular aging can reveal late-onset disease phenotypes, identifies new potential targets to modulate AD progression, and describes a strategy to program age-associated phenotypes into stem cell models of disease.
PubMed: 38917806
DOI: 10.1016/j.stem.2024.06.001 -
Journal of Pharmacological and... Jun 2024Cardiac safety assessment, such as lethal arrhythmias and contractility dysfunction, is critical during drug development. Human induced pluripotent stem cell-derived...
INTRODUCTION
Cardiac safety assessment, such as lethal arrhythmias and contractility dysfunction, is critical during drug development. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have been shown to be useful in predicting drug-induced proarrhythmic risk through international validation studies. Although cardiac contractility is another key function, fit-for-purpose hiPSC-CMs in evaluating drug-induced contractile dysfunction remain poorly understood. In this study, we investigated whether alignment of hiPSC-CMs on nanopatterned culture plates can assess drug-induced contractile changes more efficiently than non-aligned monolayer culture.
METHODS
Aligned hiPSC-CMs were obtained by culturing on 96-well culture plates with a ridge-groove-ridge nanopattern on the bottom surface, while non-aligned hiPSC-CMs were cultured on regular 96-well plates. Next-generation sequencing and qPCR experiments were performed for gene expression analysis. Contractility of the hiPSC-CMs was assessed using an imaging-based motion analysis system.
RESULTS
When cultured on nanopatterned plates, hiPSC-CMs exhibited an aligned morphology and enhanced expression of genes encoding proteins that regulate contractility, including myosin heavy chain, calcium channel, and ryanodine receptor. Compared to cultures on regular plates, the aligned hiPSC-CMs also showed both enhanced contraction and relaxation velocity. In addition, the aligned hiPSC-CMs showed a more physiological response to positive and negative inotropic agents, such as isoproterenol and verapamil.
DISCUSSION
Taken together, the aligned hiPSC-CMs exhibited enhanced structural and functional properties, leading to an improved capacity for contractility assessment compared to the non-aligned cells. These findings suggest that the aligned hiPSC-CMs can be used to evaluate drug-induced cardiac contractile changes.
PubMed: 38917571
DOI: 10.1016/j.vascn.2024.107530 -
PloS One 2024Human induced pluripotent stem cells (hiPSCs) derived into neurons offer a powerful in vitro model to study cellular processes. One method to characterize functional...
Human induced pluripotent stem cells (hiPSCs) derived into neurons offer a powerful in vitro model to study cellular processes. One method to characterize functional network properties of these cells is using multielectrode arrays (MEAs). MEAs can measure the electrophysiological activity of cellular cultures for extended periods of time without disruption. Here we used WTC11 hiPSCs with a doxycycline-inducible neurogenin 2 (NGN2) transgene differentiated into neurons co-cultured with primary human astrocytes. We achieved a synchrony index ∼0.9 in as little as six-weeks with a mean firing rate of ∼13 Hz. Previous reports show that derived 3D brain organoids can take several months to achieve similar strong network burst synchrony. We also used this co-culture to model aspects of blood-brain barrier breakdown by using human serum. Our fully human co-culture achieved strong network burst synchrony in a fraction of the time of previous reports, making it an excellent first pass, high-throughput method for studying network properties and neurodegenerative diseases.
Topics: Humans; Astrocytes; Induced Pluripotent Stem Cells; Coculture Techniques; Neurons; Cell Differentiation; Cells, Cultured; Nerve Tissue Proteins; Basic Helix-Loop-Helix Transcription Factors; Electrodes; Blood-Brain Barrier
PubMed: 38917115
DOI: 10.1371/journal.pone.0303901 -
JCI Insight Jun 2024Little is known about the expression patterns and functions of circular RNAs (circRNAs) in the heart of large mammals. In this study, we examined the expression profiles...
Little is known about the expression patterns and functions of circular RNAs (circRNAs) in the heart of large mammals. In this study, we examined the expression profiles of circRNAs, microRNAs (miRNAs), and messenger RNAs (mRNAs) in neonatal pig hearts. Pig heart samples collected on postnatal days 1 (P1), 3 (P3), 7 (P7) and 28 (P28) were sent for total RNA sequencing. Our data revealed a total of 7000 circRNAs in the 24 pig hearts. Pathway enrichment analysis of hallmark gene sets demonstrated that differentially expressed circRNAs are engaged in different pathways. The most significant difference was observed between P1 and the other three groups (P3, P7 and P28) in pathways related to cell cycle and muscle development. Out of the ten circRNAs that were validated through real-time quantitative polymerase chain reaction (qRT-PCR) to confirm their expression, six exhibited significant effects on cell cycle activity in human induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs) following small interfering RNA-mediated knockdown. The circRNA-miRNA-mRNA networks were constructed to understand the potential mechanisms of circRNAs in the heart. In conclusion, our study provided a dataset for exploring the roles of circRNAs in pig hearts. In addition, we identified several circRNAs that regulate cardiomyocyte cell cycle.
PubMed: 38916964
DOI: 10.1172/jci.insight.175625 -
BioRxiv : the Preprint Server For... Jun 2024Cartilage plays a crucial role in skeletal development and function, and abnormal development contributes to genetic and age-related skeletal disease. To better...
UNLABELLED
Cartilage plays a crucial role in skeletal development and function, and abnormal development contributes to genetic and age-related skeletal disease. To better understand how human cartilage develops , we jointly profiled the transcriptome and open chromatin regions in individual nuclei recovered from distal femurs at 2 fetal timepoints. We used these multiomic data to identify transcription factors expressed in distinct chondrocyte subtypes, link accessible regulatory elements with gene expression, and predict transcription factor-based regulatory networks that are important for growth plate or epiphyseal chondrocyte differentiation. We developed a human pluripotent stem cell platform for interrogating the function of predicted transcription factors during chondrocyte differentiation and used it to test . We expect new regulatory networks we uncovered using multiomic data to be important for promoting cartilage health and treating disease, and our platform to be a useful tool for studying cartilage development .
STATEMENT OF SIGNIFICANCE
The identity and integrity of the articular cartilage lining our joints are crucial to pain-free activities of daily living. Here we identified a gene regulatory landscape of human chondrogenesis at single cell resolution, which is expected to open new avenues of research aimed at mitigating cartilage diseases that affect hundreds of millions of individuals world-wide.
PubMed: 38915712
DOI: 10.1101/2024.06.12.598666 -
BioRxiv : the Preprint Server For... Jun 2024Human organoid model systems have changed the landscape of developmental biology and basic science. They serve as a great tool for human specific interrogation. In order...
Human organoid model systems have changed the landscape of developmental biology and basic science. They serve as a great tool for human specific interrogation. In order to advance our organoid technology, we aimed to test the compatibility of a piezoelectric material with organoid generation, because it will create a new platform with the potential for sensing and actuating organoids in physiologically relevant ways. We differentiated human pluripotent stem cells into spheroids following the traditional human intestinal organoid (HIO) protocol atop a piezoelectric nanofiber scaffold. We observed that exposure to the biocompatible piezoelectric nanofibers promoted spheroid morphology three days sooner than with the conventional methodology. At day 28 of culture, HIOs grown on the scaffold appeared similar. Both groups were readily transplantable and developed well-organized laminated structures. Graft sizes between groups were similar. Upon characterizing the tissue further, we found no detrimental effects of the piezoelectric nanofibers on intestinal patterning or maturation. Furthermore, to test the practical feasibility of the material, HIOs were also matured on the nanofiber scaffolds and treated with ultrasound, which lead to increased cellular proliferation which is critical for organoid development and tissue maintenance. This study establishes a proof of concept for integrating piezoelectric materials as a customizable platform for on-demand electrical stimulation of cells using remote ultrasonic waveforms in regenerative medicine.
PubMed: 38915647
DOI: 10.1101/2024.06.12.598673 -
BioRxiv : the Preprint Server For... Jun 2024Cerebral organoids (COs) are a valuable tool to study the intricate interplay between glial cells and neurons in brain development and disease, including HIV-associated...
Cerebral organoids (COs) are a valuable tool to study the intricate interplay between glial cells and neurons in brain development and disease, including HIV-associated neuroinflammation. We developed a novel approach to generate microglia containing COs (CO-iMs) by co-culturing hematopoietic progenitors and induced pluripotent stem cells. This approach allowed for the differentiation of microglia within the organoids concomitantly to the neuronal progenitors. CO- iMs exhibited higher efficiency in generation of CD45 /CD11b /Iba-1 microglia cells compared to conventional COs with physiologically relevant proportion of microglia (∼7%). CO-iMs exhibited substantially higher expression of microglial homeostatic and sensome markers as well as markers for the complement cascade. CO-iMs showed susceptibility to HIV infection resulting in a significant increase in several pro-inflammatory cytokines/chemokines and compromised neuronal function, which were abrogated by addition of antiretrovirals. Thus, CO-iM is a robust model to decipher neuropathogenesis, neurological disorders, and viral infections of brain cells in a 3D culture system.
PubMed: 38915632
DOI: 10.1101/2024.06.13.598579