Abstract The Mediator complex, a vital transcriptional coregulator in eukaryotes, partners with transcription factors to orchestrate gene transcription and in turn many developmental and physiological processes. Mediator subunit MED15 is required for the pre-natal development and post-natal maturation of pancreatic β-cells in mice. However, whether MED15 plays a role in β-cell function after initial development and throughout adulthood is unknown. To investigate the role of MED15 in β-cells post-maturation, we induced a β-cell specific Med15 knockout at six weeks age in male and female mice. This post-developmental Med15 ablation led to glucose intolerance and impaired insulin secretion. RNA-sequencing revealed downregulation of β-cell maturation markers, indicating that MED15 is continuously required to maintain β-cell functionality. Further, we implanted insulin pellets into Med15 knockout mice to lower blood glucose and used RNA-seq to validate that the transcriptional changes we observed are a direct consequence of Med15 loss and not an indirect effect of hyperglycemia arising in the knockout mice. In sum, our study shows that MED15 is continuously required after weaning to maintain functional β-cell maturity. Article Highlights Mediator complex subunit MED15 is required for post-natal β-cell maturation, but its role in adult β-cells was unknown Ablation of Med15 in β-cells of adult mice resulted in glucose intolerance and loss of maturation β-cell maturity and transcriptional defects are not rescued by controlling glycemia with insulin implants MED15 is required to maintain β-cell maturation post-weaning and sustain β-cell function throughout life

The generation of insulin-producing, stem cell-derived β cells (SC-β cells) from human embryonic or induced pluripotent stem cells holds promise for treating type 1 diabetes. Transplantation of SC-β cells is already in clinical testing, but generating mature cells with insulin-secreting properties similar to endogenous cells has been challenging. Given that macrophages are essential for islet development, we hypothesized that they could enhance SC-β cell differentiation and function. We coaggregated autologous SC-macrophages that were either unpolarized (SC-MUnp) or polarized to inflammatory (SC-MInf) or regenerative (SC-MReg) states during stage 7 of SC-β cell differentiation. SC-MRegs improved maturity marker expression, glucose-stimulated insulin secretion, and metabolic activity in SC-β cells. Transplantation of SC-β cells coaggregated with SC-MRegs into diabetic mice normalized glycemia significantly faster than transplantation of SC-β cells alone. The finding that addition of macrophages during SC-β differentiation accelerates functional maturation represents a notable advance in the production of SC-β cells as a regenerative cell therapy for type 1 diabetes.

AimsType 1 diabetes is caused by immune-mediated destruction of beta cells. Interestingly, individuals with long-standing type 1 diabetes have residual beta cells, suggesting regenerative mechanisms may help beta cell survival. Islet-resident macrophages have an important role in diabetes, and can adopt a tissue-regenerating phenotype that may support beta cells. However, the roles of macrophages in beta cell survival, function, and proliferation remain poorly defined. This study aimed to elucidate how macrophage subtypes influence beta cell survival, function, and proliferation.MethodsMouse and human islets were isolated from the pancreas and co-cultured in vitro with macrophages. To investigate whether macrophages enhance beta cell survival and function, apoptosis was measured using flow cytometry, and insulin secretion was assessed via glucose-stimulated insulin secretion assays. We also examined whether macrophages increased beta cell proliferation in the presence of harmine, a DYRK1A inhibitor. Finally, we evaluated the effect of islet co-culture on macrophage phenotype by flow cytometry and cytokine secretion analysis.ResultsWe found that regenerative, but not pro-inflammatory, macrophages enhanced beta cell survival and function through mechanisms that did not require direct cell contact. Direct contact between macrophages and islets promoted a macrophage regenerative phenotype characterized by increased CD206 expression and secretion of anti-inflammatory factors. Additionally, regenerative macrophages promoted beta cell proliferation in the presence of harmine.ConclusionsOur findings demonstrate that regenerative macrophages support pancreatic beta cell survival, function, and proliferation. Harnessing the regenerative properties of macrophages could offer a novel strategy to promote beta cell survival and function.

The rising global incidence of pancreatitis, pancreatic cancer, and diabetes has increased the need for efficient in vivo gene manipulation approaches to study the pancreas and develop new therapies. Although transgenic mouse models are widely used, they are time-consuming and costly to generate and maintain. Systemic viral delivery methods offer greater flexibility but often lack pancreatic specificity and require high viral doses. Here, we describe a streamlined protocol for intrapancreatic ductal delivery of adeno-associated viruses (AAVs) for targeted gene delivery. Our protocol requires standard surgical equipment and can be implemented in most laboratories. Specifically, we adopted a clamping strategy at the hepatopancreatic duct near the liver, as well as beneath the major duodenal papilla at the duodenum. This strategy exposes the duodenal papilla, facilitating viral delivery, preventing backflow, and enabling efficient pancreatic transduction at lower viral doses. Overall, this method provides a fast, simple, and effective approach for pancreas-targeted gene manipulation, facilitating preclinical studies of pancreatic biology and disease.

Abstract Background Type 2 diabetes (T2D) is a leading cause of morbidity and mortality worldwide. Despite the availability of multiple glucose-lowering agents, only half of individuals with T2D achieve the recommended HbA1c target of < 7.0%. Precision medicine approaches that leverage patient-specific markers offer a promising strategy to improve therapeutic outcomes. The PAM gene encodes the sole enzyme responsible for amidating bioactive hormones, including GLP-1, and harbors two hypomorphic T2D-risk alleles (p.D563G and p.S539W); however, whether PAM regulates GLP-1, a key amidated incretin hormone, and whether this influences response to GLP-1 receptor agonist (GLP-1RA) therapy, remains unknown. Methods PAM amidation activity, postprandial GLP-1 levels, and the incretin effect were measured in carriers of PAM T2D-risk alleles and matched non-carriers from the Oxford Biobank in a prospective observational study and in Danish cohorts. Inducible whole-body Pam knockout mice were generated; gastric emptying was assessed by paracetamol absorption assay with and without exendin-4. Glycemic response to GLP-1RAs was evaluated in a meta-analysis of 1,119 participants across three cohorts (IMI-DIRECT, GoDARTS, PRIBA), with comparative assessment of sulphonylurea, metformin, and DPP-4 inhibitor response. Results Carriers of p.S539W and p.D563G alleles demonstrated 52% and 20% reductions in serum PAM amidation activity, respectively. Both human carriers and Pam knockout mice exhibited elevated circulating GLP-1 levels; however, p.S539W carriers showed an 18% reduction in endogenous GLP-1 sensitivity. PamKO mice displayed accelerated gastric emptying that was refractory to exendin-4, alongside impaired cAMP signaling downstream of the GLP-1 receptor in the pylorus. In the clinical meta-analysis, p.S539W carriers showed a significantly attenuated HbA1c reduction following GLP-1RA therapy (− 0.69% vs. − 1.24% in non-carriers; p = 0.025), representing a 44% relative loss of glycemic benefit; only 11.5% of carriers achieved HbA1c < 7% compared with 25.3% of non-carriers. No differences in response to sulphonylureas, metformin, or DPP-4 inhibitors were observed. Conclusions Hypomorphic PAM T2D-risk alleles reduce amidating enzyme activity, elevate circulating GLP-1 levels, and impair GLP-1 post-receptor signaling, culminating in a selective and clinically meaningful reduction in GLP-1RA efficacy. These findings establish PAM genotype as a novel pharmacogenomic determinant of GLP-1RA response, supporting its incorporation into precision medicine frameworks to optimize drug selection in T2D management. Trial registration NCT02723110, NCT02465515 and NCT01144338.

Abstract Pancreatic islet macrophages support islet homeostasis and adapt their metabolic program in response to environmental cues, including beta cell released factors. Intercellular mitochondrial transfer is a biological process that modulates cellular responses. To test whether beta cells, which are strongly secretory, transfer mitochondria to islet macrophages, we generated mice with beta cell-specific expression of mitochondrial GFP (PhAM flox Ins1 Cre ). We demonstrate that beta cells transfer mitochondria to islet macrophages in vivo and in vitro . Diabetogenic stressors did not alter the frequency of mitochondrial transfer and macrophages containing beta cell-derived GFP exhibit increased protein synthesis rates. RNA-seq identified upregulation of activity-regulated cytoskeleton associated protein ( Arc ) in macrophages receiving beta cell-derived mitochondria, while disruption of actin cytoskeleton dynamics prevented mitochondrial transfer. Together, these findings identify mitochondrial transfer as a previously unrecognized mechanism of beta cell-macrophage communication that may contribute to islet homeostasis and immune regulation.

Pancreatic islet-resident immune cells, such as lymphocytes and macrophages, support islet homeostasis, beta cell development, and tissue repair. In pathological states, including diabetes, islet immune cells can trigger inflammation, causing beta cell dysfunction and death. There has been growing interest in understanding the dynamics between beta cells and resident immune cells. Studying metabolic adaptations in beta cells and immune cells is challenging due to the mixed cell populations in islets and limited cell number, which are not suitable for conventional approaches, such as metabolomics and extracellular flux analysis. We implemented a puromycin-based flow cytometry assay for parallel analysis of the phenotype and metabolic state of islet-resident immune cells. Islets were isolated from healthy mice and exposed to a cytokine cocktail (IL-1β, TNF-α, IFN-γ) to mimic a pro-inflammatory diabetogenic microenvironment. We found that Islet-resident macrophages show higher expression of CD86 and lower expression of CD301 upon cytokine treatment, which was accompanied by reduced protein synthesis rates upon inhibition of glycolysis and mitochondrial complex V. In insulin-producing beta cells, inhibition of mitochondrial complex V (ATP synthase) by oligomycin reduces translation rates. Streptozotocin (STZ)-induced beta cell death promoted accumulation of macrophages in the islet and higher frequency of CD86+ macrophages, as was observed in vitro. Islet macrophages from STZ-treated mice showed higher basal protein synthesis rates and enhanced sensitivity to oligomycin. We validated this method in bone marrow-derived macrophages and the MIN6 beta cell line, using extracellular flux analysis as a control for the puromycin-based assay. We propose our implementation of a puromycin-based assay as a useful tool to study metabolic demands in rare islet cell populations. Applying phenotypic and protein synthesis assays coupled with specific metabolic pathway inhibitors to intact pancreatic islets can provide a better understanding of the immunometabolic cues that lead to beta cell dysfunction and failure in diabetes.

The global incidence of type 1 diabetes (T1D) continues to rise, yet reliable biomarkers for predicting disease onset remain limited. Studies have demonstrated persistent proinsulin secretion in individuals living with T1D, suggesting a processing impairment. Proinsulin is processed into mature active insulin by the prohormone convertases PC1/3, PC2, and carboxypeptidase E. We hypothesized that elevated circulating proinsulin-to-C-peptide (PI:C) ratios precede the onset of diabetes and are associated with reduced expression of PC1/3 in pancreatic beta cells. Non-obese diabetic (NOD) mice were monitored for changes in plasma proinsulin, C-peptide, and beta cell Pc1/3 levels prior to diabetes onset. Female NOD mice that progressed to diabetes exhibited increased plasma proinsulin and PI:C ratios several weeks before the onset of diabetes compared to mice that remained normoglycemic. Plasma proinsulin levels were predictive of diabetes onset, with earlier elevations observed in mice that progressed to disease more rapidly. These increases in plasma proinsulin and PI:C ratios correlated with reduced beta cell Pc1/3 expression. These findings support the potential of plasma proinsulin and PI:C ratios as predictive biomarkers for T1D development and implicate diminished Pc1/3 expression as a possible mechanism underlying impaired proinsulin processing. ### Competing Interest Statement The authors have declared no competing interest. Canadian Institutes of Health Research, https://ror.org/01gavpb45, Vanier Canada Graduate Scholarship Diabetes Canada, https://ror.org/00arvcr78, OG-3-22-5644-CV CIHR-Breakthrough T1D, TDP-186359 Breakthrough T1D Canada Centre of Excellence at UBC, 3-COE-2022-1103-M-B Canadian Islet Research Training Network, NSERC-CREATE PhD Award

ABSTRACTThe endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) helps decide β cell survival in diabetes. The alternative eukaryotic initiation factor 2A (EIF2A) has been proposed to mediate EIF2S1-independent translation during cellular stress and viral infection, but its role in β cells is unknown. EIF2A abundance is high in human and mouse islets relative to other tissues, and both thapsigargin and palmitate significantly increasedEIF2AmRNA and EIF2A protein levels in MIN6 cells, mouse islets and human islets. Knockdowns of EIF2A, the related factor EIF2D, or both EIF2A and EIF2D, were not sufficient to cause apoptosis. On the other hand, transient or stable EIF2A over-expression protected MIN6 cells, primary mouse islets, and human islets from ER stress-induced, caspase-3-dependent apoptosis. Mechanistically, EIF2A overexpression decreased ERN1 (also known as IRE1α) expression in thapsigargin-treated MIN6 cells or human islets.In vivo, β cell specific EIF2A viral overexpression reduced ER stress, improved insulin secretion, and abrogated hyperglycemia inIns2Akita/WTmice. EIF2A overexpression significantly increased expression of genes involved in protein translation and reduced expression of pro-apoptotic genes (e.g. ALDH1A3). Remarkably, the decrease in global protein synthesis during UPR was prevented by EIF2A, despite ER stress-induced EIF2S1 phosphorylation. The protective effects of EIF2A were additive to those of ISRIB, a drug that counteracts the effects of EIF2S1 phosphorylation. Cells overexpressing EIF2A showed higher expression of translation factor EIF2B5, which may contribute to the lack of translational inhibition in these cells. We conclude that EIF2A is a novel target for β cell protection and the circumvention of EIF2S1-mediated translational repression.

Myeloid cells, including macrophages, neutrophils, dendritic cells, and myeloid-derived suppressor cells, play crucial roles in the innate immune system, contributing to immune defense, tissue homeostasis, and organ development. They have tremendous potential as therapeutic tools for diseases such as cancer and autoimmune disorders, but harnessing cell engineering strategies to enhance potency and expand applications is challenging. Recent advancements in stem cell research have made it possible to differentiate human embryonic stem cells and induce pluripotent stem cells into various cell types, including myeloid cells, offering a promising new approach to generate myeloid cells for cell therapy. In this review, we explore the latest techniques for the genetic engineering of myeloid cells, discussing both established and emerging methodologies. We examine the challenges faced in this field and the therapeutic potential of engineered myeloid cells. We also describe examples of engineered macrophages, neutrophils, and dendritic cells in various disease contexts. By providing a detailed overview of the current state and future directions, we aim to highlight progress and ongoing efforts toward harnessing the full therapeutic potential of genetically engineered myeloid cells.

Residual pancreatic beta cells in type 1 diabetes show reduced insulin production but the mechanisms remain unclear. Beta cells undergo stress responses during type 1 diabetes, including endoplasmic reticulum (ER) stress and DNA damage-associated senescence, which may affect insulin production. ER stress reduces insulin production but whether senescence disrupts insulin production in human beta cells has not been investigated. DNA damage-mediated senescence was induced using bleomycin in human donor islets. Relative levels of prohormone convertase 1/3 (PC1/3), prohormone convertase 2 (PC2), carboxypeptidase E (CPE) and the endogenous PC1/3 inhibitor, proprotein convertase subtilisin/kexin type 1 inhibitor (proSAAS), were quantified by western blot. Levels of proinsulin and insulin were measured by ELISA. Flow cytometry was used to measure insulin expression in islet cells. FACS was used to sort endogenous senescent beta cells from islets for analysis of insulin content. Proinsulin immunofluorescence staining was quantified in endogenous senescent vs non-senescent beta cells in pancreas tissue from control donors and donors with type 1 diabetes. Publicly available datasets were used to interrogate relationships between senescence effectors, proinsulin-processing genes and insulin content. DNA damage was induced with bleomycin in the non-proliferative female-fetus-derived EndoC-βH5 human beta cell model to study the impact of the DNA damage response on insulin production in clonal cells growth-arrested due to p16INK4A expression. DNA damage-mediated senescence led to increased PC1/3 without changes in levels of PC2, CPE or proSAAS in human islets. Consistent with these changes, no significant differences in proinsulin or insulin content were observed, compared with control islets. Flow cytometry confirmed maintenance of insulin content in DNA damage-mediated senescent beta cells vs control cells and sorted endogenous senescent beta cells had similar insulin content to non-senescent beta cells. Proinsulin staining was similar in endogenous senescent vs non-senescent beta cells from a control donor and donor with type 1 diabetes. Analysis of proteomics datasets from Humanislets.com and single-cell RNA-seq datasets from the Human Pancreas Analysis Program corroborated these findings. In EndoC-βH5 beta cells, which are growth-arrested, DNA damage led to decreased levels of CPE and proSAAS, and reduced levels of insulin. Our findings suggest that the expression of proinsulin-processing enzymes and the production of insulin are sustained in both chemically induced DNA damage-related senescence and in endogenous senescent adult human beta cells. Collectively, these findings suggest that senescent beta cells may be a source of insulin production among residual beta cells in type 1 diabetes.

HumanIslets.com supports diabetes research by offering easy access to islet phenotyping data, analysis tools, and data download. It includes molecular omics, islet and cellular function assays, tissue processing metadata, and phenotypes from 547 donors. As it expands, the resource aims to improve human islet data quality, usability, and accessibility.

Group 2 innate lymphoid cells (ILC2s) that produce interleukin (IL)-10 (IL-10+ILC2s) have demonstrated regulatory and tissue-protective properties in murine studies, but preclinical studies are lacking that explore the potential of human IL-10+ILC2s as a tolerance-promoting cell therapy for transplantation or autoimmunity. Here, we investigated whether human IL-10+ILC2s could enhance islet function and prevent allograft rejection in humanized mouse models of islet transplantation. In vitro, human IL-10+ILC2s did not display cytotoxicity toward allogeneic deceased-donor islets or stem cell-derived islet-like cells, and co-transplantation with IL-10+ILC2s significantly improved glucose control post-transplantation. Allogeneic IL10+ILC2s directly inhibited T cell-mediated cytotoxicity against islet-like cells in vitro and, in an antigen-specific transplant rejection model, prevented T cell-mediated rejection of deceased-donor islet grafts. Effects were greater with allogeneic IL-10+ILC2s, as autologous cells did not inhibit T cell interferon-γ production or cytotoxic activity in vitro and were not sufficient to prevent islet rejection in vivo. Collectively, these studies provide proof-of-principle that human IL-10+ILC2s have therapeutic potential for islet transplantation and type 1 diabetes and support their use as an allogeneic regulatory cell therapy.

Xanthine oxidoreductase (XOR) inhibitors are used to treat gout, inhibiting uric acid production, which causes clinical symptoms. Commonly used XOR inhibitors are the small molecule febuxostat (Fbx) and the purine analogue allopurinol (Allo). Recent studies show that XOR inhibitors can reduce mature interleukin (IL)-1β production by activated macrophages. This effect is not due to reduced uric acid crystal formation, which can induce NLRP3 inflammasome activation, but an independent effect. Fbx and Allo have been used interchangeably in in vitro studies to highlight the role of XOR in pro-inflammatory macrophage function. Here, we analysed the effects of Fbx and Allo on pro-inflammatory macrophage signatures. Both XOR inhibitors maintain pro-inflammatory macrophage metabolic and phenotypic hallmarks. However, only Fbx reduces the activity of caspase-1 and the release of IL-1β by preventing inflammasome assembly in macrophages isolated from both mice and humans. Our study identified an Fbx-specific reduction in IL-1β production, which could be used clinically to reduce the deleterious effects of macrophage-derived IL-1β.

Islet amyloid contributes to beta cell failure in type 2 diabetes through several mechanisms, one being the potent induction of local islet inflammation through activating inflammatory pathways in islet macrophages. As islet amyloid has recently been reported in pancreases of people with type 1 diabetes, and islet macrophages are thought to play a role in the pathogenesis of type 1 diabetes, we sought to understand the impact of islet amyloid on islet macrophages and beta cell autoimmunity. We performed an unbiased phenotypic investigation of islet macrophages in the early stage of islet amyloid formation using single-cell RNA-seq of resident islet macrophages in mice with and without the amyloidogenic form of human islet amyloid polypeptide (hIAPP). The role of islet amyloid in autoimmune diabetes and antigen presentation was assessed in hIAPP-expressing NOD mice and in antigen-presenting cells ex vivo. MHC class II (MHCII) antigen presentation genes were strongly downregulated in islet macrophages during islet amyloid formation. NOD mice expressing an hIAPP transgene had delayed diabetes relative to littermate controls (median onset 30.3 vs 19.5 weeks, p=0.016). Likewise, physiological expression of hIAPP by genetic knockin also delayed diabetes in NOD mice relative to littermate controls (median onset 28.2 vs 18.0 weeks, p=0.049), corresponding with decreased markers of antigen presentation and activation, as well as decreased immune cell infiltration in islets. Adoptive transfer studies showed that systemic autoimmune function remained intact and beta cells from hIAPP transgenic mice did not evade immune recognition by diabetogenic T cells, collectively indicating the protection from diabetes was mediated by decreased antigen presentation in the pancreas. Consistent with this, incubation of dendritic cells with islet amyloid polypeptide (IAPP) aggregates decreased MHCII surface expression and diminished antigen-specific T cell activation through a phagocytosis-dependent mechanism. Collectively, our data reveal a novel role for IAPP aggregates in decreasing MHCII antigen presentation and show that despite the well-established proinflammatory response of macrophages to IAPP aggregates, the uptake of IAPP aggregates during early amyloid formation also disrupts beta cell autoimmunity and delays diabetes in NOD mice.

α cells secrete proglucagon peptides to regulate nutrient metabolism. Recent findings support an α cell-to-β cell axis that is mediated by paracrine signaling through the glucagon receptor and glucagon-like peptide 1 (GLP-1) receptor in β cells. To address which proglucagon peptides stimulate insulin secretion, we developed an assay to quantify levels of GLP-1(7-36)NH2. We also generated three transgenic mouse lines that allow α cell-specific, inducible deletion of the genes for the two prohormone convertase enzymes that process proglucagon . Our studies reveal that both mouse and human islets contain GLP-1(7-36)NH2, but glucagon mediates α cell-to-β cell communication in mice. However, in the absence of normal production of glucagon, α cells up-regulate prohormone convertase 1 (PC1/3) to generate GLP-1 and enhance glucose tolerance. Human islets have substantially higher levels of GLP-1 than mice, which positively correlate with rates of insulin secretion. These studies show plasticity in proglucagon processing to support α cell-to-β cell communication.

OBJECTIVES:Carriers of PAM (peptidylglycine alpha-amidating monooxygenase) coding variant alleles have reduced insulinogenic index, higher risk of developing type 2 diabetes (T2D), and islets from heterozygous carriers of the PAM p.Asp563Gly variant display reduced insulin secretion. Exactly how global PAM deficiency contributes to hyperglycemia remains unclear. PAM is the only enzyme capable of converting glycine-extended peptide hormones into amidated products. Like neuropeptide Y (NPY), α-melanocyte stimulating hormone (αMSH), and glucagon-like peptide 1 (GLP-1), islet amyloid polypeptide (IAPP), a beta cell peptide that forms islet amyloid in type 2 diabetes, is a PAM substrate. We hypothesized that Pam deficiency limited to beta cells would lead to reduced insulin secretion, prevent the production of amidated IAPP, and reveal the extent to which loss of Pam in β-cells could accelerate the onset of hyperglycemia in mice. METHODS:PAM activity was assessed in human islets from donors based on their PAM genotype. We generated beta cell-specific Pam knockout (Ins1Cre/+, Pamfl/fl; βPamKO) mice and performed islet culture, histological, and metabolic assays to evaluate the physiological roles of Pam in beta cells. We analyzed human IAPP (hIAPP) amyloid fibril forming kinetics using synthetic amidated and non-amidated hIAPP peptides, and generated hIAPP knock-in beta cell-specific Pam knockout (hIAPPw/w βPamKO) mice to determine the impact of hIAPP amidation on islet amyloid burden, islet graft survival, and glucose tolerance. RESULTS:PAM enzyme activity was significantly reduced in islets from donors with the PAM p. Asp563Gly T2D-risk allele. Islets from βPamKO mice had impaired second-phase glucose- and KCl-induced insulin secretion. Beta cells from βPamKO mice had larger dense-core granules and fewer and shorter cilia. Interestingly, non-amidated hIAPP was less fibrillogenic in vitro, and high glucose-treated hIAPPw/w βPamKO islets had reduced amyloid burden. Despite these changes in beta cell function, βPamKO mice were not more susceptible to diet-induced hyperglycemia. In vitro beta cell death and in vivo islet graft survival remained comparable between hIAPPw/w βPamKO and hIAPPw/w islets. Surprisingly, aged hIAPPw/w βPamKO mice had improved insulin secretion and glucose tolerance. CONCLUSIONS:Eliminating Pam expression only in beta cells leads to morphological changes in insulin granules, reduced insulin secretion, reduced hIAPP amyloid burden and altered ciliogenesis. However, in mice beta-cell Pam deficiency has no impact on the development of diet- or hIAPP-induced hyperglycemia. Our data are consistent with current studies revealing ancient, highly conserved roles for peptidergic signaling in the coordination of the diverse signals needed to regulate fundamental processes such as glucose homeostasis.