Search Results (454)

Variants in the human PAX4 gene are associated with both monogenic and complex forms of diabetes, yet their pathogenic effects remain difficult to define in models that accurately mimic human islet architecture and neonatal metabolic transitions. Here, we created a porcine PAX4 loss-of-function model using CRISPR/Cas9 cytidine deaminase base editing to introduce a premature stop codon in the PAX4 coding sequence. PAX4 knockout piglets developed severe hyperglycemia within 24 h of birth, followed by rapid postnatal clinical deterioration and uniform death by day 3. Biochemical analysis showed significant diabetic decompensation, including electrolyte imbalances, hyperosmolality, azotemia, dyslipidemia, and metabolic acidosis. Gross and histological examinations revealed notable pancreatic hypoplasia with preservation of exocrine tissue. Single-nucleus RNA sequencing and immunohistochemistry demonstrated an almost complete loss of insulin- and somatostatin-producing β- and δ-cells, respectively, with relative preservation of glucagon-expressing α-cells. Overall, these results establish PAX4 as a crucial factor in pancreatic endocrine development and postnatal glucose regulation in a large-animal model. This platform offers a human-relevant system for studying diabetes-associated PAX4 variants and for testing regenerative and gene-based therapies for insulin-deficient diabetes. Full article

Diabetes mellitus represents a major global health challenge with rapidly increasing prevalence and substantial morbidity driven by metabolic and vascular complications. Extracellular vesicles (EVs) have emerged as critical mediators of intercellular communication and are increasingly implicated in the pathogenesis and progression of diabetes. This review summarizes current knowledge on EV biology, including their classification, cellular sources, biogenesis, uptake mechanisms, and molecular cargo. We discuss the contribution of EV-associated microRNAs to immune dysregulation and β-cell damage in type 1 diabetes mellitus (T1DM), as well as the role of EVs in insulin resistance, metabolic signaling, and vascular dysfunction in type 2 diabetes mellitus (T2DM). Particular emphasis is placed on EV-mediated modulation of endothelial function, angiogenesis, and tissue repair, alongside their involvement in the impairment of insulin receptor integrity. We further explore how lifestyle factors may influence EV composition and function, highlighting their potential integration into preventive strategies. Finally, we evaluate the emerging therapeutic potential of EVs as biomarkers and delivery systems, while addressing current limitations and future directions. Collectively, EVs represent a promising frontier in understanding diabetes pathophysiology and developing innovative diagnostic and therapeutic approaches. Unlike previous reviews that examine EVs separately as biomarkers or therapeutic vehicles, this review integrates emerging evidence supporting EVs as mediators of systemic communication linking pancreatic islets, adipose tissue, immune cells, vascular endothelium, kidney, heart, and retina throughout diabetes progression. We further critically evaluate translational barriers that currently limit clinical implementation of EV-based diagnostics and therapeutics. Full article

Background: Pathological aggregation of islet amyloid polypeptide (IAPP) contributes to β-cell dysfunction in type 2 diabetes. Our previous studies demonstrated that caveolin-1 (Cav-1) deficiency protects β-cells from palmitate-induced apoptosis. Microarray profiling further indicated that Cav-1 silencing alters IAPP expression. This study aimed to investigate the effects of Cav-1 depletion on IAPP secretion and expression and to explore the potential involvement of thioredoxin-interacting protein (TXNIP). Methods: We performed lentiviral-mediated Cav-1 knockdown in NIT-1 cells and isolated murine islets, and simultaneously generated an inducible β-cell-specific Cav-1 knockout (iβ-Cav1 KO) mouse model. IAPP secretion and expression were assessed by ELISA, Western blot, qPCR and immunofluorescence. The expression of IAPP-processing enzymes (PAM, PC1, and PC2) and degradation factors (IDE and BACE2) was examined. Co-immunoprecipitation (Co-IP) and immunofluorescence were performed to investigate the interaction between Cav-1 and TXNIP. Results: Cav-1 depletion significantly reduced both IAPP secretion and expression in vitro and in vivo. High-fat-diet-fed iβ-Cav1 KO mice exhibited the lowest serum IAPP levels. Mechanistically, Cav-1 depletion was associated with downregulation of PAM, PC1, and PC2 and upregulation of IDE and BACE2. Additionally, Cav-1 depletion decreased TXNIP expression. Immunofluorescence revealed co-localization of Cav-1 and TXNIP, and co-immunoprecipitation further demonstrated their direct physical interaction. Conclusions: Cav-1 is essential for IAPP secretion and expression in β-cells. The direct physical interaction between Cav-1 and TXNIP suggests that TXNIP may mediate the regulatory effects of Cav-1 on IAPP processing or secretion. These findings identify the Cav-1–TXNIP axis as a potential target for mitigating IAPP-related β-cell dysfunction. Full article

Background: Type 2 diabetes is projected to affect millions of people annually as the number of cases rises year on year. This includes children. Treating diabetes and its related comorbidities has a huge economic impact and puts pressure on healthcare providers. Understanding the disease at a molecular level is key for developing better therapeutics. The protein Islet Amyloid Polypeptide (IAPP) or amylin is important for glucose regulation; however, it is also instrumental in type 2 diabetes pathology. Human IAPP can misfold into oligomers and amyloid fibrillar aggregates within pancreatic islets, promoting β-cell dysfunction and death, contributing to progressive insulin deficiency and worsening hyperglycaemia. Methods: Based on previous studies on mutations at residues 18, 28 and 31,we have designed three novel IAPP analogues (two double and one triple mutant) to assess whether the combined amino acid substitutions impact fibril formation, solubility and toxicity. Results: All three of our analogues show a reduced propensity to aggregate and are more soluble than wild type IAPP. Compared with pramlintide, a clinically prescribed synthetic analogue of human amylin, all of our analogues appeared to have similarly reduced toxicity and improved solubility relative to human IAPP. Additionally, two of our analogues exhibited a markedly slower rate of fibril formation. Conclusions: Our results highlight the importance of targeting multiple residues as a promising strategy for developing improved diabetes therapeutics in the future. Full article

Type 1 diabetes is caused by autoimmune destruction of insulin-secreting β-cells within islets of Langerhans. Transplantation of donor islets can improve glycaemic control, but current clinical islet transplantation protocols are compromised by extensive loss of β-cell functional mass soon after implantation. Co-incubation in vitro or co-transplantation in vivo of mesenchymal stromal cells (MSCs) with isolated islets improves their functional survival, although the underlying mechanisms remain obscure. Here, we show that MSC-derived extracellular vesicles (MSC-EVs) are alone sufficient to recapitulate many of the beneficial effects of MSCs on islet functional survival, offering the possibility of simple cell-free treatments to improve the outcomes of islet transplantation. We used LC- analysis and small RNA sequencing to analyse the protein and microRNA (miRNA) molecular cargos of MSC-EVs. Proteomic analysis identified >100 proteins from the Uniprot Mouse Database, including β-cell G protein-coupled receptor (GPCR) agonists which we have previously shown to enhance β-cell functional survival. MSC-EVs contained ~300 distinct miRNAs and we identified five highly enriched miRNAs that were significantly upregulated in MSC-EV-treated islets, notably miR-21a-5p. MSC-EV treatment also altered the expression of a distinct set of islet mRNAs known to be involved in islet metabolism and function. These observations may enable the further simplification of the islet pretreatment strategy by focusing on defined GMP-grade biologically active molecules rather than whole heterogeneous EV populations. Full article

The gut microbiota is increasingly recognized as an important factor in the pathogenesis of type 1 diabetes (T1D), although its exact role in disease initiation and progression remains uncertain. Earlier interpretations considered alterations in intestinal microbial composition as secondary effects of immune dysregulation or metabolic disturbance. Recent longitudinal studies, however, suggest that specific microbial changes occur before the onset of islet autoimmunity, indicating a potential contributory role in the early phases of disease development. In this narrative review article, the gut–pancreas axis (GPA) is described as a dynamic and reciprocal system in which microbial, metabolic, and immune processes influence each other to shape β-cell outcomes. Evidence from human cohorts and experimental models links early life reductions in microbial diversity, impaired intestinal barrier function, and decreased production of short-chain fatty acids (SCFAs) to altered immune activation and β-cell damage. Microbiota transferred from individuals at risk for T1D has been shown to accelerate disease in animal models, supporting a possible causal relationship. Although experimental models support mechanistic links between microbiota alterations and autoimmune diabetes, current human evidence remains largely associative. Together, these findings suggest that microbial and immune networks interact in a feedback manner that can sustain immune tolerance or promote autoimmunity depending on environmental and host factors. Understanding T1D as a state of disrupted microbial and immune integration provides a basis for restoring gut–pancreas communication and preserving β-cell integrity. Full article

Diabetes mellitus is a chronic and progressive metabolic disorder associated with abnormal blood glucose levels. The term involves several diseases with different pathophysiology mechanisms and treatment strategies. Stem cell-based treatments represent an emerging strategy for patients with diabetes mellitus with severe pancreatic insufficiency and poor glycemic control. Over the last 20 years, researchers have investigated mesenchymal stem cell infusion and the transplantation of stem cell-derived β cells and islet tissues. This review aims to comprehensively discuss the latest advances in the field of stem cell use in diabetes, including clinical studies and preclinical experiments aiming at improving the efficacy and safety of stem cell use. Full article

Glucose-stimulated insulin secretion is the central functional readout of pancreatic islets, yet existing assays often require offline processing or pooling of multiple islets, limiting real-time assessment of single-islet function. Here we report a microscopy-compatible islet-on-a-chip (IOC) integrated with light scattering-based broadband backscattering confocal microscopy (BBCM) for continuous, label-free optical readout of insulin secretion dynamics in functional human islets. Fabricated using two-photon polymerization, the IOC-BBCM sensor stabilizes single human islets under continuous perfusion for high-resolution optical interrogation. The sensor identifies insulin-rich β-cells label-free, as confirmed by insulin immunostaining, and monitors granule depletion and redistribution during glucose and potassium chloride (KCl) stimulation, matching ELISA-quantified insulin secretion from the same perfused islets. This modular sensor provides a non-destructive, label-free approach for monitoring stimulus-linked secretion dynamics from individual human islets and should support longitudinal studies of islet function. Full article

Mitochondrial RNA (mtRNA) modifications have emerged as critical regulators of pancreatic β-cell bioenergetics, influencing glucose-stimulated insulin secretion (GSIS) and the early pathogenesis of diabetes mellitus (DM). This review synthesizes current evidence on the diversity, mechanisms, and functional implications of mtRNA modifications—such as N6-methyladenosine (m6A), 5-methylcytosine (m5C), pseudouridine (Ψ), and 5-formylcytosine (f5C)—within β-cell mitochondria. These chemical marks, installed and recognized by specific writer, eraser, and reader proteins, regulate mitochondrial translation, oxidative phosphorylation (OXPHOS) complex assembly, and redox balance. Defects in mtRNA modification machinery, exemplified by β-cell-specific knockout of TFB1M, MRM2, or PUS1, impair ribosome biogenesis, disrupt ATP production, and precipitate insulin secretory failure, as demonstrated in human islets, rodent models, and monogenic diabetes syndromes. Advances in epitranscriptomic mapping technologies—including nanopore direct RNA sequencing, RNA immunoprecipitation (RIP)-seq, and mass spectrometry—have enabled high-resolution profiling of mtRNA modification landscapes under physiological and diabetic conditions, revealing their dynamic regulation in response to metabolic stress. Furthermore, mtRNA modifications interact with environmental stressors, such as oxidative damage and toxic metals, modulating β-cell vulnerability via pathways like the mitochondrial unfolded protein response (UPRmt). Therapeutically, modulation of RNA-modifying enzymes or restoration of specific chemical marks holds promise for preserving β-cell function, with potential applications in early diagnosis, risk stratification, and precision medicine approaches for DM. Despite substantial progress, critical gaps remain in understanding the interplay between mtRNA modifications, mitochondrial-nuclear crosstalk, and β-cell plasticity. Addressing these gaps will be pivotal for translating mtRNA biology into novel biomarkers and targeted interventions for early-stage diabetes. Full article

Type 1 diabetes (T1D) is an immune-mediated disease characterized by progressive autoimmune destruction of pancreatic β cells. Although traditionally viewed as primarily T-cell-driven, B cells play essential roles in disease pathogenesis. In addition to producing islet autoantibodies, B cells contribute to immune activation through antigen presentation and cytokine secretion, thereby shaping autoreactive T-cell responses. The earliest clinical predictor of T1D is the appearance of islet autoantibodies in the blood, reflecting a breach in B-cell tolerance well before symptomatic disease onset. In individuals at high genetic risk, type I interferon (IFN) signatures are detectable in peripheral blood prior to seroconversion, suggesting that type I IFNs may act as upstream regulators of B-cell tolerance. Peripheral tolerance is enforced through layered checkpoints including transitional selection, maintenance of anergy, germinal center regulation, and regulatory B-cell differentiation. Studies in systemic autoimmunity demonstrate that type I IFN signaling lowers B-cell activation thresholds, enhances BCR and TLR responsiveness, promotes survival of autoreactive transitional clones via BAFF induction, destabilizes anergy, and skews differentiation toward inflammatory phenotypes such as T-bet+ age-associated B cells. Consistent with this model, single-cell transcriptomic and BCR repertoire analyses in T1D reveal clonal expansion and proinflammatory signatures in islet-reactive B cells during the preclinical stage. Together, these findings implicate the IFN–B-cell axis as a potential target for early disease modification. Full article

G protein-coupled receptors (GPCRs) constitute the largest family of membrane receptors and are critical regulators of β-cell physiology. Nearly 300 GPCRs are expressed in human islets, where they integrate metabolic, hormonal, neuronal, and inflammatory cues to control insulin secretion, proliferation, and survival. Altered GPCR signaling contributes to β-cell dysfunction and the pathogenesis of both type 1 and type 2 diabetes. This review provides an overview of GPCR functions in β-cell biology, highlighting receptors that stimulate or inhibit glucose-stimulated insulin secretion, as well as those influencing β-cell fate. We also examine GPCR biosynthesis, trafficking, and subcellular localization—processes that shape receptor availability and signaling specificity. Aberrant folding, retention, or misrouting of GPCRs can disrupt β-cell function and contribute to metabolic disease. Thus, beyond receptor pharmacology, understanding the molecular mechanisms governing GPCR biogenesis and spatial distribution is essential for designing targeted strategies to preserve β-cell function and improve glucose homeostasis. Full article

Type 2 Diabetes (T2D) is characterized by the toxic aggregation of human islet amyloid polypeptide (hIAPP or amylin) within pancreatic β-cells. IAPP is also a neuropancreatic hormone that plays a significant role in Alzheimer’s disease (AD) by co-depositing with amyloid-beta (Aβ) and Tau, supporting the Type 3 Diabetes (T3D) hypothesis. Soluble IAPP accelerates Aβ aggregation through cross-seeding and causes neurotoxicity by impairing the blood–brain barrier and activating neuroinflammation. Melatonin inhibits these processes by disrupting hydrophobic interactions in both hIAPP and Aβ, preventing the formation of toxic β-sheet structures. Furthermore, melatonin promotes amyloid clearance via the glymphatic and lymphatic systems, protects neurons from oxidative damage, and reduces Tau hyperphosphorylation. This suggests that melatonin serves as a promising multitarget therapeutic agent for both metabolic and neurodegenerative disorders by modulating structural protein transformations. Full article

Diabetes mellitus remains a leading cause of morbidity worldwide, driven in type 1 diabetes by autoimmune destruction of pancreatic β-cells and in advanced type 2 diabetes by progressive β-cell dysfunction and failure. Diabetes affects around 830 million people globally, with the vast majority residing within low- and middle-income nations. Over the last few decades, the numbers of people who have diabetes and those with untreated diabetes have consistently increased. Although current pharmacologic therapies improve glycemic control, they do not restore functional β-cell mass. Consequently, strategies aimed at protecting, regenerating, or replacing insulin-producing cells have emerged as a major focus of regenerative medicine. Stem cell-based approaches offer the potential to generate renewable sources of glucose-responsive β-like cells, but challenges remain in achieving full functional maturation, immune protection, scalable manufacturing, and durable clinical engraftment. This review examines advances in engineering stem cell-derived insulin-producing cells for islet replacement therapy, with an emphasis on differentiation strategies, immunoprotective approaches, and the translational barriers that must be addressed for durable β-cell replacement. Full article

The islet amyloid polypeptide (IAPP) is a peptide hormone playing key biological roles, including glucose homeostasis and regulation of food intake, conferring high therapeutic potential to treat metabolic disorders. Nonetheless, IAPP is mainly known as the major component of the amyloid fibrils observed in the pancreatic islets of patients afflicted with type 2 diabetes, and the accumulation of these insoluble protein deposits correlates closely with the loss of pancreatic β-cells. The inherent aggregation propensity of this peptide hormone is not only associated with the pathogenesis of type 2 diabetes but also complicates the design of IAPP derivatives for the treatment of metabolic disorders. Accordingly, elucidating the molecular mechanisms by which IAPP self-assembles into amyloid fibrils is critical to identify chemical strategies to arrest aggregation, as well as to design safe and stable IAPP-derived therapeutics. This review aims at presenting the different mechanistic models of IAPP aggregation and how to exploit this information to identify inhibitors of amyloid formation and non-aggregating peptide agonists. After discussing the conformational conversions allowing IAPP to undergo a mainly disordered monomeric conformation into ordered cross-β-sheet quaternary supramolecular structures, we present chemical strategies to prevent amyloid deposition and to develop non-aggregating peptide-based therapeutics. Full article

Type 2 diabetes (T2D) is a pressing global health challenge, primarily driven by modern dietary and lifestyle patterns. Central to T2D progression is the dysfunction of insulin-secreting pancreatic β-cells, which critically disrupts glucose homeostasis. The progression to T2D relies on the β-cells’ inability to compensate for increasing insulin resistance. Initially, β-cells enhance the insulin output, but chronic nutrient overload, ER stress and inflammation ultimately compromise their function and survival. This review examines the molecular and cellular drivers of β-cell failure, focusing on endoplasmic reticulum stress, mitochondrial dysfunction and inflammatory pathways amid chronic metabolic stress. We also explore the loss of β-cell identity and altered interactions within the islet microenvironment. Understanding these mechanisms is essential for developing strategies to prevent β-cell dysfunction and slow T2D progression, ultimately supporting better metabolic health outcomes. Full article