Disease Models & Mechanisms最新文献

In vivo models that replicate and reproduce human lung cancer and its response to therapy are necessary for the development of new therapeutic strategies and understanding drug resistance. Imaging lung tumors in live animals to monitor tumor growth and response to therapy is challenging owing to the location of the lungs and their constant movement during breathing. X-ray velocimetry (XV) is a novel functional lung imaging technique that maps regional lung expansion during breathing, providing spatial information on where ventilation changes occur. The aim of this pilot study was to use XV and flexiVent lung mechanics assessments to determine the effect of tumor growth on lung function in mice at 2 or 3 weeks post tumor induction and to evaluate the efficacy of these two tools. Histological analysis showed that tumor growth was not uniform between animals. At 3 weeks post tumor induction, some XV ventilation and flexiVent lung mechanics parameters were significantly different from baseline. Both techniques gave metrics that correlated with the tumor counts from the histology. In some mice, XV revealed localized regions with altered expansion rates.

Because the intestinal epithelium is exposed to various stressors, dysregulation of essential mechanisms that maintain gut homeostasis, such as autophagy, has been linked to inflammatory bowel pathologies. In Drosophila melanogaster, inhibition of autophagy specifically in adult intestinal stem cells (ISCs) affects their proportions differently during aging. Proper intestinal renewal requires a balance between ISC proliferation and differentiation. Here, we showed that, in adult ISCs, loss of core autophagy genes and regulators of autophagosome-lysosome fusion increases the enteroendocrine cell population and enhances the transcriptional activity of Stat92E. Functional experiments involving cell fate regulators of enteroendocrine or enterocyte differentiation and proliferation suggested that dysfunctional autophagy in adult ISCs enhances Stat92E activity downstream of Hop/JAK kinase. Finally, lineage-tracing analyses confirmed that autophagy inhibition promotes enteroendocrine cell differentiation. Thus, our data demonstrate that, under homeostatic conditions, basal autophagy limits enteroendocrine cell differentiation by regulating Stat92E activity, which can be counteracted by the transcription factor Scute.

Drosophila has long been a powerful model for cancer research, yet the development of robust metastatic tumor models remains a challenge. Although allograft transplantation offers a promising approach, its use has been limited by technical constraints. Here, we established a reproducible serial transplantation protocol using lgl mutant brain tumors, enabling exponential expansion of tumor material and precise tracking of temporal tumor progression. Extending this approach to other neural stem cell (NSC)-derived tumors, we identified shared metastatic characteristics between lgl and pins mutants. Additionally, we compared tumors of different tissue origins, demonstrating that epithelial tumors, like NSC tumors, can also be serially propagated. Using these models, we showed that tumors metastasize to host organs, establish tumor colonies in the ovaries, distort the gastrointestinal tract and invade the cellular cortex of the adult brain. Overall, our study provides a systematic framework for generating metastatic tumors in adult flies from two distinct tissue origins, establishing organ-specific metastatic patterns and offering a platform for studying tumor-host interactions at secondary organ sites.

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous motile ciliopathy characterized by chronic respiratory disease, laterality defects, hydrocephalus and infertility, caused by impaired function of motile cilia. LRRC56 has recently emerged as a novel PCD candidate gene, but its role in vertebrate cilia remains poorly understood. Here, we used Xenopus laevis multiciliated cells, targeted knockdown and in vivo imaging to investigate lrrc56 function, and combined these studies with in vivo affinity purification-mass spectrometry (AP-MS) to define its interactome. We show that loss of lrrc56 causes specific depletion of outer dynein arms (ODAs) from the distal axoneme. In vivo AP-MS revealed that Lrrc56 binds the ODA docking complex components, including Odad3. Consistently, lrrc56 knockdown also led to distal loss of Odad3. Moreover, we show that disease-associated variants in LRRC56 and ODAD3 disrupted their localization and interaction, pointing to a shared functional pathway. Our work demonstrates that lrrc56 is a critical regulator of distal ODAs and ODA docking complex deployment and provides new mechanistic insight into PCD, advancing our broader understanding of motile cilia biology.

Asthma, a chronic inflammatory airway disease, remains a major global health concern. Fibroblasts, the cell type responsible for tissue repair and fibrosis, are therefore a potential therapeutic target for asthma-related lung disease. However, the role of fibroblasts in the onset and progression of asthma is poorly understood. Thus, we sought to determine the effects of fibroblast loss on lung homeostasis and asthma development using a transgenic mouse model to ablate PDGFRα+ fibroblasts. We observed a consistent reduction in PDGFRα+ cells (75-85% in the mesenchyme), which persisted for several months. The PDGFRα+ fibroblast-ablated lungs exhibited a reduced number of lipofibroblasts, altered extracellular matrix gene expression and increased neutrophils in both the bronchoalveolar lavage fluid and the lung tissues under steady-state conditions. When asthma was induced, we found that loss of PDGFRα+ fibroblasts resulted in increased mucous production, neutrophil activation and proinflammatory cells, such as interstitial macrophages and eosinophils, which can worsen asthma. These findings highlight the essential roles of PDGFRα+ fibroblasts in maintaining immune balance and how their loss leads to dysregulated airway immune composition and remodeling, contributing to asthma pathogenesis.

Centronuclear myopathies (CNMs) are rare congenital muscle disorders with no effective treatment. Previous studies showed that tamoxifen improved muscle function in mice modeling CNMs caused by variants in MTM1, BIN1 and DNM2. Here, we investigated whether tamoxifen administration improves muscle function and pathology in the severe recessive Ryr1TM/indel mouse model of RYR1-related CNM. Contractile performance, histological analyses and protein levels were assessed in Ryr1TM/indel mice and control littermates (wild type) treated with either a tamoxifen-enriched diet (65 mg/kg of food) or a control diet for 5 weeks, beginning at 3 weeks of age. Ryr1TM/indel mice displayed muscle weakness, reduced myofiber size and a high number of fibers with nuclei in abnormal position, regardless of the treatment. Force production during repeated contractions was reduced in tamoxifen-treated Ryr1TM/indel mice compared to that in untreated Ryr1TM/indel mice. The levels of CNM proteins (DNM2 and BIN1) were unchanged following the treatment. Tamoxifen did not improve muscle dysfunction, atrophy or histological hallmarks in Ryr1TM/indel mice. Our data indicate that tamoxifen supplementation is not beneficial and may negatively impact muscle function in this model of CNM, suggesting limited therapeutic value for patients with RYR1 mutations.

Margaret (Peggy) Goodell has significantly advanced our understanding of haematopoietic stem cells - the stem cells that develop into different types of specialised blood cells. She is Professor and Chair of the Department of Molecular and Cellular Biology at Baylor College of Medicine in Houston, TX, USA. Peggy completed her PhD at the University of Cambridge, UK, before returning to the USA to carry out postdoctoral work at the Whitehead Institute for Biomedical Research, in Cambridge, MA, where she pioneered a novel technique for isolating haematopoietic stem cells, known as the 'side population' method. She then joined Baylor College of Medicine in 1997 to start her own lab and has stayed there since. Peggy's research focuses on regulatory mechanisms in haematopoietic stem cells and how these go awry during ageing and disease. The significance of her research has been recognised by multiple prestigious awards, including the Tobias Award from the International Society for Stem Cell Research and the Dameshek Prize from the American Society of Hematology. In this 'A Model for Life' interview, we discuss Peggy's impressive career path, the parallels between ageing and cancer in the blood, and the lessons we can learn from stem cell biology to understand and mitigate disease.

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by inflammation and joint destruction. Replicating human manifestations of RA in animal models remains challenging, however, owing to heterogeneity of the disease. In this study, a humanized mouse model for RA was developed and validated using NOD-scid IL2Rγnull (NSG) mice engrafted with peripheral blood mononuclear cells (PBMCs) from patients with RA (NSG-RA). RA symptoms were induced using lipopolysaccharide and a cocktail of antibodies against type II collagen. Pathological manifestations were assessed through clinical scoring of hind paw swelling, histological analysis, and evaluation of RA-specific markers in plasma and joints using Luminex, RT-PCR and RNA sequencing. NSG-RA mice exhibited increased levels of RA-specific markers, an influx of inflammatory cells into the synovium, bone erosion and elevated levels of human autoantibodies. Enriched RNA-sequencing pathway analysis revealed activation of the RA disease pathway, along with the TNF and IL-17 signalling pathways. Treatment with prednisolone or infliximab ameliorated disease symptoms and decreased levels of inflammatory markers. These findings indicate that the NSG-RA model offers a translational tool for studying RA pathogenesis and testing novel therapeutic approaches.

The intestine is a rich source of hormones that regulate metabolism. Among these are glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), both expressed by L-cells. These hormones play important roles in promoting satiety; however, how they are regulated transcriptionally is not known. ETS variant transcription factor 1 (ETV1) is expressed by L-cells, but its function remains unknown. Here, we examined Etv1 expression in single-cell RNA-sequencing (scRNA-seq) datasets from the mouse small intestine and from organoid cultures. To assess the functional role of ETV1, loss-of-function and overexpression experiments were performed in organoids. Gene expression was subsequently assessed with quantitative PCR and scRNA-seq. Our results confirmed Etv1 enrichment in the L-cell lineage both in vivo and in organoids. Furthermore, mutations in ETV1 led to a decrease in Pyy expression levels with no effect on Gcg levels or on overall cell composition and organoid morphology. Moreover, overexpression of ETV1 led to a modest, but specific, increase in Pyy levels. We thus identified ETV1 as a regulator of Pyy expression, illustrating, for the first time, how specific hormones in the L-cell lineage are transcriptionally regulated.