Journal of Clinical Investigation最新文献

Large-cohort genome-wide association studies (GWAS) for alcohol use disorder (AUD) drug treatment outcomes and AUD risk have repeatedly identified genetic loci which are splicing quantitative trait loci for the fibronectin III domain containing 4 (FNDC4) gene in the brain. However, FNDC4 function in the brain and how it might contribute to AUD pathophysiology remain unclear. In the present study, we characterized GWAS loci-associated FNDC4 splice isoforms and demonstrated that FNDC4 alternative splicing results in loss-of-function for FNDC4. We also investigated FNDC4 function using CRISPR/cas9 editing, and the creation of human induced pluripotent stem cell (iPSC)-derived neural organoids joined with single-nucleus RNA sequencing, a series of studies which showed that FNDC4 knock-out (KO) resulted in a striking shift in the relative proportions of glutamatergic and GABAergic neurons in iPSC-derived forebrain organoids as well as changes in their electrical activity. We further explored potential mechanism(s) of FNDC4-dependent neurogenesis with results that suggested a role for FNDC4 in mediating neural cell surface interactions. In summary, this series of experiments indicates that FNDC4 plays a role in regulating cerebral cortical neurogenesis in the brain. This regulation may contribute to the response to AUD pharmacotherapy as well as the effects of alcohol on the brain.

The urokinase plasminogen activator receptor (uPAR) is a membrane-bound protein found on the surface of immune cells. Through the action of proteases, uPAR is cleaved to produce several circulating proteins in the bloodstream, including the soluble form suPAR and the fragments D1 and D2D3. Initially studied in the context of infectious diseases and cancer, recent research has revealed roles for suPAR and its related proteins as mediators linking innate immunity to the pathogenesis of kidney and cardiovascular diseases, as well as insulin-dependent diabetes. While these proteins have long been recognized as prognostic biomarkers, growing clinical, experimental, and genetic evidence highlights their active involvement in the onset and progression of these diverse conditions. This Review examines suPAR's evolution from its discovery as a modulator of innate immunity to its current status as a key driver in chronic kidney and cardiovascular diseases. Furthermore, we explore the molecular mechanisms through which suPAR and D2D3 contribute to multiorgan damage, emphasizing emerging opportunities for therapeutic interventions across interconnected organ systems.

The c-Jun N-terminal kinases (JNKs) regulate diverse physiological processes. Whereas JNK1 and JNK2 are broadly expressed and associated with insulin resistance, inflammation, and stress responses, JNK3 is largely restricted to central nervous system neurons and pancreatic β cells, and its physiological role in β cells remains poorly defined. To investigate its function, we generated mice lacking JNK3 specifically in β cells (βJNK3-KO). These mice displayed glucose intolerance and defective insulin secretion, particularly after oral glucose challenge, indicating impaired incretin responses. Consistently, Exendin-4-stimulated (Ex4-stimulated) insulin secretion was blunted in βJNK3-KO islets, accompanied by reduced GLP-1R expression. Similar findings were observed in human islets treated with a selective JNK3 inhibitor (iJNK3). Downstream of GLP-1R, Ex4-induced CREB phosphorylation was diminished in βJNK3-KO islets, indicating impaired canonical signaling. Moreover, activation of the GLP-1R/CREB/IRS2 pathway, a key regulator of β cell survival, was reduced in βJNK3-KO islets and iJNK3-treated human islets. As a consequence, the protective effects of Ex4 were lost in cytokine-treated βJNK3-KO and human islets, and Ex4-mediated protection was partially attenuated in βJNK3-KO mice exposed to multiple low-dose streptozotocin. These findings identify JNK3 as a regulator of β cell function and survival and suggest that targeting this pathway may enhance incretin-based therapies.

Pancreatic cancer cells "live on the edge," starved of nutrients, compressed by abundant stiff stroma, and deprived of oxygen. In this issue, Xu et al. leveraged human pancreas organoid-based CRISPR screens to identify new driver genes in pancreatic ductal adenocarcinoma (PDAC) development. Neurofibromatosis type 2 (NF2) emerged as the top tumor suppressor, whose loss enhances PDAC malignancy. Inactivation of NF2, which encodes the protein Merlin, promoted growth factor independence and enhanced macropinocytosis upon nutrient deprivation. Thus, NF2 status dictates the adaptability of pancreatic tumors under nutrient limitation, with NF2 inactivation endowing PDACs with the ability to survive the constraints of the harsh tumor microenvironment.

Calorie restriction (CR) extends maximal lifespan and maintains cellular homeostasis in various animal models. We have previously shown that CR induces a global reduction of protein fractional synthesis rates (FSRs) across the hepatic proteome in mice, but the timing and regulatory mechanisms remain unclear. Nitric oxide (NO), a bioactive molecule upregulated during CR, is a potential regulator of protein synthesis. To explore the role of NO in hepatic proteome fluxes during CR, we used in vivo deuterium labeling from heavy water and liquid chromatography/mass spectrometry-based (LC/MS-based) flux proteomics in WT and NO-deficient (NO-) mice. We observed a transition to reduced global protein FSRs that occurred rapidly between days 25 and 30 of CR. NO deficiency, whether genetic or pharmacological, disrupted the slowing of proteome-wide fluxes and the beneficial effects on body composition and physiology. Administering the NO donor molsidomine restored the reduction in hepatic FSRs in NO- mice. Furthermore, inhibiting NO pharmacologically, whether starting on day 1, day 14, or day 24 of CR, mitigated the reduction in hepatic protein FSRs at day 32, highlighting NO's critical role during the transition period. These results underscore the importance of NO in CR-induced changes in proteostasis and suggest NO as a potential CR-mimetic target, while offering a specific time window for identifying other signals and testing therapeutic interventions.

Pancreatic ductal adenocarcinoma (PDAC) occurs as a complex, multifaceted event driven by the interplay of tumor-permissive genetic mutations, the nature of the cellular origin, and microenvironmental stress. In this study, using primary human pancreatic acinar 3D organoids, we performed a CRISPR-KO screen targeting 199 potential tumor suppressors curated from clinical PDAC samples. Our data revealed significant enrichment of a list of candidate genes, with neurofibromatosis type 2 associated gene (NF2) emerging as the top target. Functional validation confirmed that loss of NF2 promoted the transition of PDAC to an invasive state, potentially through extracellular matrix modulation. NF2 inactivation was found to enhance PDAC cell fitness under nutrient starvation. This adaptation not only reinforced the oncogenic state but also conferred therapeutic resistance. Additionally, we found that NF2 loss was associated with fibroblast heterogeneity and cancer-stroma communication in tumor evolution. These findings establish NF2 as a critical tumor suppressor in PDAC and uncover its role in mediating nutrient adaptation and drug resistance. Importantly, this study provides additional insights into drug resistance mechanisms and potential therapeutic targets in PDAC.

Inherited BAP1 mutations cause melanoma and other cancers and can also lead to white hair patches or skin spots due to pigment cell loss.

Chimeric antigen receptor T cell (CAR-T) therapy has transformed the treatment of hematologic malignancies, yet, severe inflammatory toxicities continue to limit its broader use. In this issue of the JCI, Goala et al. uncovered a mechanistic link between IFN-γ-driven inflammation and disrupted neutrophil homeostasis, revealing that cytokine release syndrome (CRS) and immune cell-associated hematologic toxicity (ICAHT) stem from a shared biological pathway. Using IL-2Ra-deficient mice and patient samples, they showed that IFN-γ suppressed IL-17A and granulocyte colony-stimulating factor (G-CSF), disrupting granulopoiesis and neutrophil survival. Strikingly, IFN-γ blockade eased both CRS and neutropenia without diminishing CAR-T efficacy, suggesting a path toward safer, better-tolerated cell therapies.

Connections between the digestive system and the brain have been postulated for over 2000 years. Despite this, only recently have specific mechanisms of gut-brain interaction been identified. Due in large part to increased interest in the microbiome, the wide use of incretin-based therapies (i.e., glucagon-like peptide 1 [GLP-1] receptor agonists), technological advancements, increased understanding of neuroimmunology, and the identification of a direct enteroendocrine cell-neural circuit, research in the past 10 years has made it abundantly clear that the gut-brain connection plays a role both in clinical disease as well as the actions of therapeutics. In this Review, we describe mechanisms by which the gut and brain communicate and highlight human and animal studies that implicate changes in gut-brain communication in disease states in gastroenterology, neurology, psychiatry, and endocrinology. Furthermore, we define how GLP-1 receptor agonists for obesity and guanylyl cyclase C agonists for irritable bowel syndrome leverage gut-brain mechanisms to improve patient outcomes. This Review illustrates the critical nature of gut-brain communication in human disease and the potential to target gut-brain pathways for therapeutic benefit.