Coupled myovascular expansion directs cardiac growth and regeneration
Ontology highlight
ABSTRACT: Purpose: The goal of this experiment is to better understand the molecular mediators of myovascular coupling during growth and injury. Methods: We performed single cell RNA-sequencing (scRNA-Seq) of border zones of cryoinjured murine hearts collected at P7 using the Drop-seq protocol. Results: Together with in situ hybridization data, results from the scRNA-seq data analysis support a dynamic role for myocardial VEGFA to endothelial VEGFR2 signaling as a regulator of the myovascular expansion during growth and regeneration.
Project description:Kilian2024 - Immune cell dynamics in Cue-Induced Extended Human Colitis Model
Single-cell technologies such as scRNA-seq and flow cytometry provide critical insights into immune cell behavior in inflammatory bowel disease (IBD). However, integrating these datasets into computational models for dynamic analysis remains challenging. Here, Kilian et al., (2024) developed a deterministic ODE-based model that incorporates these technologies to study immune cell population changes in murine colitis. The model parameters were optimized to fit experimental data, ensuring an accurate representation of immune cell behavior over time. It was then validated by comparing simulations with experimental data using Pearson’s correlation and further tested on independent datasets to confirm its robustness. Additionally, the model was applied to clinical bulk RNA-seq data from human IBD patients, providing valuable insights into immune system dynamics and potential therapeutic strategies.
Figure 4c, obtained from the simulation of human colitis model is highlighted here.
This model is described in the article:
Kilian, C., Ulrich, H., Zouboulis, V.A. et al. Longitudinal single-cell data informs deterministic modelling of inflammatory bowel disease. npj Syst Biol Appl 10, 69 (2024). https://doi.org/10.1038/s41540-024-00395-9
Abstract:
Single-cell-based methods such as flow cytometry or single-cell mRNA sequencing (scRNA-seq) allow deep molecular and cellular profiling of immunological processes. Despite their high throughput, however, these measurements represent only a snapshot in time. Here, we explore how longitudinal single-cell-based datasets can be used for deterministic ordinary differential equation (ODE)-based modelling to mechanistically describe immune dynamics. We derived longitudinal changes in cell numbers of colonic cell types during inflammatory bowel disease (IBD) from flow cytometry and scRNA-seq data of murine colitis using ODE-based models. Our mathematical model generalised well across different protocols and experimental techniques, and we hypothesised that the estimated model parameters reflect biological processes. We validated this prediction of cellular turnover rates with KI-67 staining and with gene expression information from the scRNA-seq data not used for model fitting. Finally, we tested the translational relevance of the mathematical model by deconvolution of longitudinal bulk mRNA-sequencing data from a cohort of human IBD patients treated with olamkicept. We found that neutrophil depletion may contribute to IBD patients entering remission. The predictive power of IBD deterministic modelling highlights its potential to advance our understanding of immune dynamics in health and disease.
This model was curated during the Hackathon hosted by BioMed X GmbH in 2024.
Project description:VEGFA administration has been explored as a pro-angiogenic therapy for cardiovascular diseases including heart failure for several years; however, many challenges remain. Here we investigate a different approach to augmenting VEGFA bioavailability, one that achieves more physiological VEGFA concentrations by deleting VEGFR1/FLT1, a VEGFA decoy receptor. We find that, following cryoinjury, zebrafish flt1 mutant hearts display enhanced coronary revascularization and endocardial expansion, increased cardiomyocyte dedifferentiation and proliferation, and decreased scarring. Suppressing Vegfa signaling in flt1 mutants abrogates the beneficial effects of flt1 deletion. Transcriptomic analyses of cryoinjured flt1 mutant hearts revealed enhanced endothelial MAPK/ERK signaling and downregulation of the transcription factor gene egr3. Using genetic tools, we observe egr3 upregulation in the regenerating endocardium and find that Egr3 promotes myofibroblast differentiation. These data suggest that with enhanced VEGFA bioavailability, the cardiac endothelium limits myofibroblast differentiation via egr3 downregulation, thereby providing a more permissive microenvironment for cardiomyocyte replenishment after injury.
Project description:Single-cell RNA sequencing (scRNA-seq) offers new possibilities to address biological and medical questions. However, systematic comparisons of the performance of diverse scRNA-seq protocols are lacking. We generated data from 583 mouse embryonic stem cells to evaluate six prominent scRNA-seq methods: CEL-seq2, Drop-seq, MARS-seq, SCRB-seq, Smart-seq and Smart-seq2. While Smart-seq2 detected the most genes per cell and across cells, CEL-seq2, Drop-seq, MARS-seq and SCRB-seq quantified mRNA levels with less amplification noise due to the use of unique molecular identifiers (UMIs). Power simulations at different sequencing depths showed that Drop-seq is more cost-efficient for transcriptome quantification of large numbers of cells, while MARS-seq, SCRB-seq and Smart-seq2 are more efficient when analyzing fewer cells. Our quantitative comparison offers the basis for an informed choice among six prominent scRNA-seq methods and provides a framework for benchmarking further improvements of scRNA-seq protocols.
Project description:Exaggerated signaling by vascular endothelial growth factor (VEGF) A and its receptor, VEGFR2, in pathologies results in poor vessel function. Still, pharmacological suppression of VEGFA/VEGFR2 may aggravate disease. Delineating VEGFR2 signaling in vivo provides strategies for suppression of specific VEGFR2-induced pathways. Three VEGFR2 tyrosine residues (Y949, Y1212, Y1173) induce downstream signaling. Here, we show that knock-in of phenylalanine to create VEGFR2 Y1212F in C57Bl/6 and FVB mouse strains leads to loss of growth factor receptor bound (GRB)2- and phosphoinositide 3´kinase (PI3K)p85-signaling. C57Bl/6 Vegfr2Y1212F/Y1212F show reduced embryonic endothelial cell (EC) proliferation and partial lethality. FVB Vegfr2Y1212F/Y1212F show reduced postnatal EC proliferation. Reduced EC proliferation in Vegfr2Y1212F/Y1212F explants is rescued by c-Myc overexpression. We conclude that VEGFR2 Y1212 signaling induces activation of extracellular-signal regulated kinase (ERK)1/2 and Akt pathways required for c-Myc-dependent gene regulation, endothelial proliferation and vessel stability. We use microarray to determine the differences in gene expression in endothelial cells between WT or Vegfr2Y1212F/Y1212F mice.
Project description:We studied CGNPs with conditional deletion of Eed using scRNA-seq. Eed was deleted in CGNPs by crossing Math1-Cre mice with Eed floxed mice. scRNA-seq seq was performed by Drop-seq. The results may be compared to our prior published data on scRNA-seq in normal CGNPs (GEO accession number GSE129730)
Project description:To comprehensively study how club cells response to airway epithelial injury, we performed single cell transcriptomic analysis of the normal and NAPH injured lung samples. Our analysis reveals that a previously undescribed pathway promoting mucous metaplasia that involves VEGFa and its receptor KDR. Our single cell RNA sequencing analysis revealed that VEGFR2 (also known as FLK1 or KDR) is expressed in club cell subpopulations. Loss of KDR, its ligand VEGFa, or downstream MEK/ERK causes excessive differentiation of club cells into mucous cells (mainly goblet cells) during development and regeneration following Naphthalene (NAPH) challenge.
Project description:The KRAS G12D mutation is a key oncogenic driver in many solid tumors, including pancreatic, gastric, and colorectal cancers. While recent preclinical studies have characterized features associated with innate and acquired KRAS G12D inhibitor resistance, strategies to overcome resistance, especially in the gastrointestinal cancer context, remain underexplored. Here, we generated nine gastrointestinal cancer models of acquired resistance to the KRAS G12D-selective inhibitor MRTX1133. We identified the enrichment of angiogenesis, hypoxia, and epithelial-to-mesenchymal transition (EMT) in an isogenic patient-derived organoid model of acquired resistance by single-cell RNA sequencing. In the nine resistant models, VEGFA expression and VEGFR2 phosphorylation were unanimously increased. Subsequent mechanistic studies revealed that an autocrine VEGFA signaling loop, initiated by an increased interaction between KRAS and PI3Kγ, drives both EMT and RAS independence. Elevated mitochondrial oxidative stress in resistant cells led to CCT2-mediated KRAS stabilization, thereby enhancing PI3Kγ activity. Moreover, we observed that cancer-vascular paracrine signaling both amplified angiogenesis and EMT signatures in cancer cells and promoted endothelial cell proliferation. Significantly, disruption of VEGFA signaling reversed EMT induction and restored sensitivity to MRTX1133. Concordantly, in mouse xenograft models, the combination of anti-VEGFR2 therapy and MRTX1133 rechallenge significantly reduced tumor growth, angiogenesis, and proliferation markers without adverse effects on body weight. These findings identify a critical role for VEGFA signaling in resistance to KRAS G12D inhibition and provide a rationale for combination therapies targeting angiogenesis in gastrointestinal cancers.
Project description:The KRAS G12D mutation is a key oncogenic driver in many solid tumors, including pancreatic, gastric, and colorectal cancers. While recent preclinical studies have characterized features associated with innate and acquired KRAS G12D inhibitor resistance, strategies to overcome resistance, especially in the gastrointestinal cancer context, remain underexplored. Here, we generated nine gastrointestinal cancer models of acquired resistance to the KRAS G12D-selective inhibitor MRTX1133. We identified the enrichment of angiogenesis, hypoxia, and epithelial-to-mesenchymal transition (EMT) in an isogenic patient-derived organoid model of acquired resistance by single-cell RNA sequencing. In the nine resistant models, VEGFA expression and VEGFR2 phosphorylation were unanimously increased. Subsequent mechanistic studies revealed that an autocrine VEGFA signaling loop, initiated by an increased interaction between KRAS and PI3Kγ, drives both EMT and RAS independence. Elevated mitochondrial oxidative stress in resistant cells led to CCT2-mediated KRAS stabilization, thereby enhancing PI3Kγ activity. Moreover, we observed that cancer-vascular paracrine signaling both amplified angiogenesis and EMT signatures in cancer cells and promoted endothelial cell proliferation. Significantly, disruption of VEGFA signaling reversed EMT induction and restored sensitivity to MRTX1133. Concordantly, in mouse xenograft models, the combination of anti-VEGFR2 therapy and MRTX1133 rechallenge significantly reduced tumor growth, angiogenesis, and proliferation markers without adverse effects on body weight. These findings identify a critical role for VEGFA signaling in resistance to KRAS G12D inhibition and provide a rationale for combination therapies targeting angiogenesis in gastrointestinal cancers.
Project description:Pancreatic cancer is a complex disease with a desmoplastic stroma, extreme hypoxia, and inherent resistance to therapy. Understanding the signaling and adaptive response of such an aggressive cancer is key to making advances in therapeutic efficacy and understanding disease progression. Redox factor-1 (Ref-1), a redox signaling protein, regulates the DNA binding activity of several transcription factors, including HIF-1. The conversion of HIF-1 from an oxidized to reduced state leads to enhancement of its DNA binding. In our previously published work, knockdown of Ref-1 under normoxia resulted in altered gene expression patterns on pathways including EIF2, protein kinase A, and mTOR. In this study, single cell RNA sequencing (scRNA-seq) and proteomics were used to explore the effects of Ref-1 on metabolic pathways under hypoxia.Results: We also integrated the scRNA data analysis with the proteomic analysis and found that the differentially expressed genes and pathways identified from the scRNA-seq data are highly consistent to the significant proteins observed in the proteomics data, especially for the upregulated cell cycle and transcription pathways and downregulated metabolic, apoptosis and signaling pathways under hypoxia. Conclusion: The scRNA-seq and proteomics data consistently demonstrated down-regulated central metabolism pathways in APE1/Ref-1 knockdown vs scrambled control under both normoxia and hypoxia conditions. Experimental Methods: scRNA-seq comparing pancreatic cancer cells expressing less than 20% of the Ref-1 protein was analyzed using left truncated mixture Gaussian model. Matched samples were also collected for bulk proteomic analysis of the four conditions. scRNA-seq data was validated using proteomics and qRT-PCR. Ref-1’s role in mitochondrial function was confirmed using mitochondrial function assays and qRT-PCR. Results: We also integrated the scRNA data analysis with the proteomic analysis and found that the differentially expressed genes and pathways identified from the scRNA-seq data are highly consistent to the significant proteins observed in the proteomics data, especially for the upregulated cell cycle and transcription pathways and downregulated metabolic, apoptosis and signaling pathways under hypoxia. Conclusion: The scRNA-seq and proteomics data consistently demonstrated down-regulated central metabolism pathways in APE1/Ref-1 knockdown vs scrambled control under both normoxia and hypoxia conditions.