Disease Models & Mechanisms最新文献

Optimal lysosomal function is essential for early tissue development. This is evidenced by the large number of inherited disorders, collectively called the lysosomal storage disorders (LSDs), caused by lysosomal dysfunction. While it is clear that macromolecular accumulation adversely impacts tissue development, the breadth of downstream pathways contributing to pathology has yet to be elucidated. Multiple studies indicate mechanisms beyond lysosomal storage also profoundly influence early tissue formation. Of these, abnormal growth factor signaling has been linked to pathology in several different LSDs. Recent work in a zebrafish model of sialidosis demonstrated that mislocalizing lysosomal cathepsins by increased exocytosis disrupts the TGF-ß related signaling pathways that control skeletal formation. Here we show loss of the enzyme galns (N-acetyl galactosamine-6-sulfatase) also enhances lysosomal exocytosis in developing cartilage of mutant zebrafish. Unlike sialidosis, however, in galns mutants increased exocytosis was associated with reduced cathepsin activity, lower levels of TGFß and BMP signaling, and altered abundance of intra- and extracellular glycosaminoglycans. Together these data highlight a role for lysosomal exocytosis and protease-mediated alterations in growth factor signaling in onset of MPSIVA skeletal pathology.

Quantitative behavioural analysis is a powerful approach for linking genotype to phenotype, but many existing tools require specialised hardware, extensive preprocessing, or coding expertise. We present SAMBA (Segment Anything Model for Behavioural Analysis), an open-access, Google Colab-based pipeline that harnesses the Segment Anything Model 2 (SAM2) for accurate, semi-automated tracking without thresholding or background subtraction. With minimal user input, SAMBA extracts movement parameters, detects behavioural states, and supports batch processing. Validating SAMBA in three Drosophila melanogaster models of human neurological disease revealed impaired locomotion, reduced speed, and altered decision-making. We further demonstrate adaptability to adult Drosophila and larval zebrafish, underscoring its cross-species utility. By combining foundation-model segmentation with an accessible interface, SAMBA lowers technical barriers to analysing motor pattern defects and is readily extendable to diverse model organisms, life stages, and experimental paradigms. This flexibility positions SAMBA as a valuable platform for accelerating disease mechanism studies, genetic screens, and preclinical testing.

MAP3K1 is a multifunctional signaling kinase implicated in diverse biological processes. Although its Gain-of-Function (GoF) mutations contribute to multiple human diseases, including 46,XY disorders of sex development (DSDs), mechanistic studies have been limited due to the lack of physiologically relevant in vivo models. To address this gap, we generated a Cre-inducible Map3k1TG transgenic mouse carrying V5- and TurboID-tagged Map3k1 cDNA. Upon tamoxifen-induced Cre activation, Map3k1TG;Rosa26-CreERT2 fetuses displayed tamoxifen dose-dependent lethality and developmental abnormalities, including reduced body size, digit fusion, tail shortening and epidermal thickening, demonstrating broad developmental impact of MAP3K1 overexpression. Male fetuses additionally exhibited impaired sexual differentiation, with reduced anogenital distance and decreased Sertoli and germ cell populations. Mechanistically, MAP3K1 induction activated both MAPK and WNT/β-catenin pathways, leading to β-catenin displacement from plasma membrane in keratinocytes in vitro, and in epidermal and germ cells in vivo. TurboID-based proximity labeling further revealed cytoskeletal-associated proteins as MAP3K1 interactors, consistent with biochemical and imaging evidence showing MAP3K1 colocalization with actin filaments and centrosomes. These findings establish Map3k1TG as a versatile in vivo platform for dissecting MAP3K1 GoF mechanisms in development and diseases.

The periderm is a transient epithelial layer with crucial roles in maintaining barrier integrity and preventing abnormal adhesions during midface development. Interferon regulatory factor 6 (IRF6) is a key genetic driver of periderm function. Zebrafish irf6 maternal-null embryos fail to form the periderm precursor epithelial population, termed the enveloping layer (EVL), resulting in embryonic rupture prior to gastrulation. We utilized this irf6 maternal-null model to perform a chemical screen and found that elafibranor, a dual PPARα/PPARd agonist, delayed rupture and rescued irf6 maternal-null embryos to initiate gastrulation. Elafibranor treatment restored EVL cell-cell contacts, F-actin morphology, and Zo1 localization at multiway junctions. Elafibranor also partially rescued expression of epithelial differentiation markers esrp1, tp63, and cebpb. Surprisingly, EVL structural changes preceded epithelial differentiation gene expression, suggesting that intercellular mechanical forces influence IRF6-mediated epithelial differentiation. Further, elafibranor-exposed wildtype zebrafish displayed characteristics of exacerbated adhesion, including axis shortening, craniofacial cartilage dysmorphology, and elongated periderm microridges as possible sequelae of apical epithelial constriction. These findings provide new insights into the complex interplay between tissue-level mechanical cues and transcriptional changes during early epithelial and embryonic development.

Lafora disease (LD) is a devastating form of progressive myoclonus epilepsy characterized by the accumulation of insoluble forms of glycogen [polyglucosan bodies (PGBs)] in the brain and peripheral tissues. It has been proposed that the accumulation of PGBs is pathogenic. Several mouse models of LD have been generated to study the relationship between PGBs and the pathophysiology of LD. However, the use of LD mice is difficult and time consuming; thus, more amenable cellular systems would be desirable. We recently described a cellular model based on the culture of primary postnatal astrocytes from LD mice that are able to accumulate small PGBs. In this study, we extended this astrocytic model by maturing the astrocytes for longer times. These more mature astrocyte cultures accumulated larger and granular PGBs, which have similar properties to the ones present in the hippocampus of Nhlrc1-/- (Epm2b-/-) mice. Importantly, this model expresses inflammatory mediators related to LD pathophysiology. This astrocytic model could be used to better understand the formation of the PGBs and also to define how the accumulation of PGBs activates the expression of inflammatory mediators.

Pathogenic variants in the dystrophin (DMD) gene cause muscle-wasting disorders ranging from the milder Becker muscular dystrophy (BMD) to the more severe Duchenne muscular dystrophy (DMD). Exon 45 deletion is the most-frequent single-exon deletion in patients diagnosed with DMD. Here, we generated a novel rat model with an exon 45 deletion using CRISPR/Cas9. The DmdΔ45 rat recapitulate key features of DMD, including progressive skeletal muscle degeneration, impaired muscle and cardiac function, and cognitive deficits. Transcriptomics analyses revealed gene expression patterns consistent with dystrophin deficiency. In skeletal muscle, we observed a transition from early stress responses and regeneration to chronic inflammation, fibrosis and metabolic dysfunction. Cardiac profiles similarly progressed from early inflammatory responses to fibrotic remodelling and metabolic impairment. Notably, DmdΔ45 rats displayed a milder phenotype than other DMD rat models. This attenuation is likely due to spontaneous exon skipping, particularly of exon 44, which partially restores the reading frame and increases revertant dystrophin-positive fibres with age. Downregulation of spliceosome-related genes suggests a potential mechanism for this exon skipping. Overall, this model provides valuable insights into phenotypic variability and therapeutic exon-skipping strategies.

Novel treatment strategies are urgently needed to combat Mycobacterium avium complex (MAC) pulmonary disease (PD). Animal models are important for screening therapeutic strategies, but their ability to reproduce human-like immunopathology and impaired respiratory function is poorly characterised. We modelled chronic lung infection in BALB/c mice over 20 weeks with three isolates of MAC (MAC101, MAC104 and MAC2285R) to compare bacterial growth, histological injury, immune cellular dynamics and respiratory function. We found that MAC101 caused a proliferative infection over 20 weeks, associated with a strong adaptive response, progressive granulomatous inflammation and increasing respiratory effort. For MAC104, lung bacterial burden rose initially but fell after week 12, accompanied by increased regulatory T-cell response and stabilisation of pathological and respiratory changes. By contrast, MAC2285R caused a low-virulence, non-proliferative infection associated with a strong myeloid cell response, modest histopathological change and increased respiratory effort. Immune cell dynamics in chronic murine MAC-PD correlate with bacterial burden and pathology and are strongly MAC-isolate dependent. These findings provide a spectrum of quantifiable and clinically relevant disease outcomes to facilitate the preclinical screening of novel antimicrobial and host-directed therapies for MAC-PD.

Cerebellar organoids present promising tools for the modelling of human cerebellar development and diseases. As this young field grows, robust standards and transparent reporting practices are needed to ensure the reproducibility and utility of the generated cerebellar organoid models. Here, we summarize current approaches to generate cerebellar organoids and their applications. We suggest common quality control standards and biological readouts that should be considered in this emerging area.

Fucosidosis is an ultra-rare and fatal lysosomal storage disease caused by the impaired lysosomal degradation of fucosylated glycoconjugates due to a deficiency in the lysosomal tissue α-L-fucosidase (FUCA1). The accumulation of fucosylated metabolites within lysosomes leads to a range of severe, primarily neurological, symptoms, including cognitive impairment and progressive motor dysfunction. In this study, we explored a therapeutic approach using translational readthrough (TR) for patients with premature termination codons resulting from nonsense mutations in the FUCA1 gene. We ectopically expressed several clinically identified FUCA1 nonsense variants in a cell line with low endogenous FUCA1 expression. Treatment with the aminoglycoside G418 induced TR, leading to partial recovery of the full-length enzyme and FUCA1 activity. Moreover, combining aminoglycoside treatment with CC-885-induced degradation of the eukaryotic release factor subunit eRF3a further enhanced FUCA1 restoration in two variants (p.Q82X and p.W188X). This study lays the groundwork for individualized TR therapy for patients with fucosidosis with FUCA1 nonsense variants.

Cells must properly synthesize, fold and degrade proteins to maintain protein homeostasis, or proteostasis. Studies in the model nematode host Caenorhabditis elegans have illuminated different ways in which proteostasis intersects with immune responses against pathogen infection, which is the focus of this Review. For example, pathogens often interfere with host proteostasis pathways to survive and replicate. Hosts, in turn, can sense these perturbations and then trigger immune responses, creating additional burdens on proteostasis. This Review is organized by the cellular compartments in which proteostasis pathways are activated, starting with the cytosolic processes of protein synthesis, folding, degradation and the ubiquitin-proteasome system. Next, we cover autophagy and lysosome-related processes, followed by pathways triggered in the endoplasmic reticulum and mitochondria. We discuss infections in C. elegans by bacteria, viruses, microsporidia and oomycetes; all of these pathogen types infect humans. We provide examples of how findings in C. elegans relate to mammals, noting how the coordination of proteostasis and immunity can be conserved across species. We emphasize a recurring theme in C. elegans that impairment of one proteostasis pathway can lead to compensatory activation of another pathway, ultimately providing a health benefit to the host, highlighting organismal resilience.