EMBO Molecular Medicine最新文献

Primary human pancreatic ductal organoids (HPDO) have emerged as a model to study pancreas biology and model disease like pancreatitis and pancreatic cancer. Yet, donor material availability, genetic variability and a lack of extensive benchmarking to healthy and disease pancreas limits the range of applications. To address this gap, we established porcine pancreatic ductal organoids (PPDO) as a system from a reliable, genetically defined and easily obtainable source to model pancreatic ductal/progenitor biology. We benchmarked PPDO to HPDO and primary porcine pancreas using single-cell RNA sequencing (scRNA-Seq). We observed no overt phenotypic differences in PPDO derived from distinct developmental stages using extensive proteomics profiling, with a WNT/basal cell signaling enriched population characterizing PPDO. PPDO exhibited differentiation potential towards mature ductal cells and limited potential towards endocrine lineages. We used PPDO as a chemical screening platform to assess the safety of FDA-approved drugs and showed conserved toxicity of statins and α-adrenergic receptor inhibitors between PPDO and HPDO cultures. Overall, our results highlight the PPDO as a model for mammalian duct/progenitor applications.

Cardiac hypertrophy is one of the significant causes of heart failure and is closely related to the rising rate of hospitalization and readmissions. Given the diverse regulatory roles of alternative splicing in cardiovascular diseases, RNA-binding proteins have attracted increasing research attention. Here, for the first time, we discovered elevated expression of RBMS1 in heart tissues of patients with dilated cardiomyopathy and in mice with cardiac hypertrophy. We demonstrated that RBMS1 activated the PI3K/AKT signaling pathway by promoting the splicing CTTN to generate CTTN-Δe11 splicing isoform, resulting in cytoskeleton and sarcomere damage in cardiomyocytes. Additionally, pharmacological inhibition of RBMS1 by nortriptyline alleviated cardiac hypertrophy and heart failure. These results provide a new perspective for developing novel therapeutic approaches for cardiac hypertrophy and establish a theoretical basis for targeting RBMS1 in the clinical treatment of cardiac hypertrophy.

Fungi are estimated to cause the death of almost 4 million people annually, and we urgently need new drug targets to overcome antifungal resistance. We found that four-stranded nucleic acid structures called G-quadruplexes (G4s) could form within the critical priority fungal pathogen Aspergillus fumigatus. Sequences with the potential to form G4s could be found in genes involved in fungal growth, virulence, and drug resistance. This included cyp51A, which encodes the target of azoles. Notably, we observed the formation of both canonical and unusual acid-stabilised G4s in these sequences. We found that PhenDC3 (a G4-stabilising ligand) could refold DNA into antiparallel G4 structures in cyp51A that were associated with decreased transcription. PhenDC3 also had potent fungistatic activity, prevented germination, synergised with the antifungal amphotericin B in vitro and in vivo, and displayed low genotoxicity and cytotoxicity towards human cells. Interestingly, PhenDC3 had greater antifungal activity towards the pan-azole-resistant A. fumigatus TR34/L98H isolate, and another G4-stabiliser, pyridostatin, killed multi-drug-resistant Candida auris. Taken together, G4s represent a promising target for the development of antifungals with novel mechanisms of action.

Cancer cachexia is a debilitating syndrome characterized by the progressive loss of skeletal muscle mass with or without fat loss. Recent studies have implicated dysregulation of the endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) pathways in skeletal muscle under various conditions, including cancer. In this study, we demonstrate that the IRE1α/XBP1 branch of the UPR promotes activation of the ubiquitin-proteasome system, autophagy, JAK-STAT3 signaling, and fatty acid metabolism in the skeletal muscle of the KPC mouse model of pancreatic cancer cachexia. Moreover, we show that the IRE1α/XBP1 pathway is a key contributor to muscle wasting. Skeletal muscle-specific deletion of the XBP1 transcription factor significantly attenuates tumor-induced muscle atrophy. Mechanistically, transcriptionally active XBP1 binds to the promoter regions of genes such as Map1lc3b, Fbxo32, and Il6, which encode proteins known to drive muscle proteolysis. Pharmacological inhibition of IRE1α using 4µ8C in KPC tumor-bearing mice attenuates cachexia-associated molecular changes and improves muscle mass and strength. Collectively, our findings suggest that targeting IRE1α/XBP1 pathway may offer a therapeutic strategy to counteract muscle wasting during pancreatic cancer-induced cachexia.

Coordination of cellular and physiological development by signaling is required for normal brain structure and function. Mutations in OCRL, a phosphatidylinositol 4,5 bisphosphate [PI(4,5)P₂], 5-phosphatase leads to Lowe Syndrome (LS). However, the mechanism by which mutations in OCRL leads to the neurodevelopmental phenotypes of LS is not understood. We find that on differentiation of LS patient iPSC, neural cultures show reduced excitability and enhanced GFAP levels. Multiomic single-nucleus RNA and ATACseq analysis of neural stem cells revealed enhanced numbers of cells with a gliogenic cell state. Analysis of snRNA seq revealed increased levels of DLK1, a Notch ligand in LS patient NSC associated increased levels of cleaved Notch and elevation of its transcriptional target HES5, indicating upregulated Notch signaling. Treatment of iPSC derived brain organoid with an inhibitor of PIP5K, the lipid kinase that synthesizes PI(4,5)P₂, was able to restore neuronal excitability and rescue Notch signaling defects in OCRL deficient organoids. Overall, our results demonstrate a role for PI(4,5)P₂ dependent regulation of Notch signaling, cell fate specification and neuronal excitability regulated by OCRL.

Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma, with poor outcomes in high-risk and relapsed patients. Here, we identify de novo cholesterol biosynthesis as a critical metabolic vulnerability in RMS. The transcription factor PROX1, previously implicated in RMS growth, acts as an upstream regulator of cholesterol biosynthesis, promoting expression of key pathway genes. Inhibition of cholesterol biosynthesis, either genetically or pharmacologically, impaired RMS cell proliferation, caused a broad halt of cell cycle progression, and activated ER stress-mediated apoptosis through the PERK-ATF4-CHOP axis. Notably, RMS cells could not be rescued by exogenous LDL cholesterol, indicating a unique reliance on endogenous cholesterol production, whereas normal cells, including myoblasts and astrocytes, largely relied on extracellular cholesterol uptake. Clinical and single-cell RNA-seq analyses further revealed that high expression of cholesterol biosynthesis genes correlate with poor survival and enrichment of cell cycle-related gene signatures across RMS subtypes. Together, these findings mechanistically link cholesterol biosynthesis to proliferative signaling and ER stress response in RMS and highlight this pathway as a promising, non-redundant therapeutic target.