bluuebunny/crossref_metadata_2025_split huggingface dataset:
1742-P: Loss of MAFB Compromises a-Cell Identity and Glucagon Secretion in Adult Human Islets
Authors: COATE KATIE C. , TONG XIN , LIU JIN-HUA , JENKINS REGINA , ARAMANDLA RADHIKA , DEY NANDITA , KIM SEUNG , BRISSOVA MARCELA , POWERS ALVIN C. , STEIN ROLAND 
Published: June 2023

Islet-enriched transcription factors (TFs) are critical regulators of α and β cell development and function. One such TF, MAFB, exhibits a distinct expression pattern between species in that it is restricted to α cells postnatally in rodents, but produced in both developing and adult human α and β cells. While MAFB is essential for insulin production and secretion in human embryonic stem cell models, the impact of MAFB loss in mature α and β cells is unknown. Importantly, both T1D and T2D are associated with dramatic loss of islet MAFB expression. To test the hypothesis that MAFB is a critical regulator in adult human islets, dispersed islet cells were infected with lentiviruses expressing control or MAFB knockdown (MAFBKD) shRNAs, and reaggregated for 6 days to form pseudoislets (PIs; N=6 donors, ages 16-50 years). MAFBKD PIs exhibited a 56.4±4.2% reduction (P&lt;0.001) in MAFB mRNA compared to control. Likewise, glucagon mRNA and hormone content were reduced by 42.5±6.9 and 28.6±7.6% (P&lt;0.05), respectively, whereas insulin expression and content were unchanged. In static hormone secretion experiments, IBMX- and arginine-stimulated glucagon secretion was blunted in MAFBKD PIs (~33% lower than control; P&lt;0.05), an observation that was replicated in α cell-enriched MAFBKD PIs. Insulin secretion, on the other hand, was largely unaffected. Bulk RNA-sequencing analysis of MAFBKD versus control PIs illustrated downregulation of α cell identity genes, upregulation of β, delta, and gamma cell identity genes, and misexpression of PYY, a gut peptide gene. Upregulated genes were also highly enriched in gene sets associated with epithelial mesenchymal transition and transforming growth factor β signaling. Intriguingly, marker genes in both pathways were shown recently to be upregulated in T2D α cells. Our findings suggest that MAFB is a molecular “gatekeeper” of α cell identity through gene activating and repressive functions, with its loss leading to dysregulation of human glucagon secretion.

Disclosure
K.C.Coate: None. R.Stein: None. X.Tong: None. J.Liu: None. R.Jenkins: None. R.Aramandla: None. N.Dey: None. S.Kim: None. M.Brissova: None. A.C.Powers: None.
1748-P: Assessing the Presence of Delta-Cell–Mediated Electrical Coupling in the Islet
Authors: LEVITT CLAIRE H. , BENNINGER RICHARD K. 
Published: June 2023

Somatostatin-producing delta cells play an important role in the regulation of paracrine cross talk in the islet through inhibition of insulin and glucagon secretion by beta and alpha cells, respectively. However, recent studies have suggested the presence of electrical coupling via gap junctions between delta and beta cells. Electrical coupling mediated cross-talk would support the correlation between pulsatile insulin and somatostatin release and reveal a structural source of cell-cell communication within the islet. To test whether beta and delta cells are gap junction coupled, we measured the permeability of cell to cell connections and the relative dynamics of Ca2+. Islets of Sst-Cre;Rosa-LSL-tdTomato mice were used which show delta-cell specific labelling. They were then loaded with the cationic dye rhodamine-123 at 5mM glucose to measure performance of fluorescence recovery after photobleaching to assess gap junction coupling of delta cells and non-delta cells. Calcium dynamics were assessed using calcium dye Fluo-4 upon stimulating the islet from low glucose (2mM or 5 mM) to high glucose(11mM). No significant differences between recovery rate were observed when comparing delta cells and beta cells (p&gt;0.05), which indicates some level of gap junction permeability among delta cells exists. The calcium activity of a population of delta cells was similar to those of neighboring beta cells, indicating a functional connection exists between these cell types. Furthermore, first-responder beta cells showed a preferential proximity to delta cells suggesting an impact of delta cells on functional sub-populations of nearby beta-cells. These results suggest a possible feedback system exists in the islet that is governed by electrical coupling of delta cells, which is important for both the function of beta cells and insulin secretion, and may also impact secretion of other islet hormones.

Disclosure
C.H.Levitt: None. R.K.Benninger: None.

Funding
National Institute of Diabetes and Digestive and Kidney Diseases (P30DK116073, R01DK102950, R01DK106412)
1752-P: The Role of Translocon-Associated Protein Subunit γ in Insulin Biosynthesis and Glucose Homeostasis
Authors: XU NING , XU XIAOXI , HU JINGXIN , GUO JIYUN , CUI JINGQIU , LIU MING , FENG WENLI , LI XIN 
Published: June 2023

Translocation-associated protein (TRAP) is a four-subunit complex located on the endoplasmic reticulum (ER) membrane, including TRAPα, TRAPβ, TRAPγ, and TRAPδ. TRAPα, TRAPβ and TRAPδ reside on the luminal side of the ER membrane for primary functionality, whereas the extra-membranous portion of TRAPγ is mainly cytosolic. Our recent studies indicate that TRAP complex contributes to the biosynthesis of proinsulin in pancreatic β cell lines and TRAPγ is a rate-limiting element of proinsulin biosynthesis. This might be partially explained by that newly made preproinsulin may first encounter the cytosolic domain of TRAPγ for translocation into the ER. To further understand the role of TRAPγ in β cells and its pathological significance in maintaining glucose homeostasis, we generated a β-cell specific TRAPγ knockout mouse model. We found that TRAPγ deficiency led to a significant reduction of insulin content in islets and a decrease of circulating insulin. TRAPγ βKO mice impaired glucose tolerance with aging, which even further deteriorated with high fat diet. In β cell line, TRAPγ deficiency resulted in less proinsulin synthesis and poor response to high glucose stimulation. Consistently, an acute exposure to high glucose increased expression of TRAPγ and proinsulin protein levels simultaneously in wild-type mouse islets. However, the ability to upregulate proinsulin response to high glucose was markedly compromised in TRAPγ βKO mouse islets. This study uncovers that TRAPγ is critical to insulin synthesis both in vivo and in vitro, which provides insight into the pathogenesis of type 2 Diabetes.

Disclosure
N.Xu: None. X.Xu: None. J.Hu: None. J.Guo: None. J.Cui: None. M.Liu: None. W.Feng: None. X.Li: None.

Funding
National Natural Science Foundation of China (81830025, 82220108014, 82100865, 81800733, 81900720, 82000796, 82070854); National Key R&D Program of China (2019YFA0802502, 2022YFE0131400); Tianjin Key Medical Discipline Construction Project (TJYXZDXK-030A)
1755-P: EndoC-ßH5 Is a Storable and Ready-to-Use Human Pancreatic Beta Cell That Can Model Type 1 and 2 Diabetes
Authors: OLLEIK HAMZA , BLANCHI BRUNO 
Published: June 2023

EndoC-βH5 is a newly developed human pancreatic beta cell model and an optimized version among the EndoC-βH (EndoC-βH1/2/3) family. EndoC-βH5 cells are storable and ready-to-use and they robustly and reproducibly secrete insulin in response to glucose and incretins across experiments and laboratories. Specifically, they dose dependently respond to physiological concentrations of glucose. In addition, their response to GLP-1 and GIP receptor agonists is also highly reproducible and dose-dependent. Given the continuously increasing number of diabetes patients worldwide, the need for physiologically relevant human cellular models is greater than ever and EndoC-βH5 cells represent a novel human pancreatic beta cell solution that can help developing human diabetes models and drug screening and validation assays. In this study, we are developing pathological and drug screening models. EndoC-βH5 cells are sensitive to palmitate/high glucose as well as cytokine induced cell loss, recapitulating hallmarks of T2D. In addition, we evaluated impairment of insulin secretion and ER stress in these contexts in order to assess the mechanistic relevance of the models. We then addressed T1D modeling. We generated HLA-A2 expressing EndoC-βH5 cells and evaluated HLA-A2 alloreactive T lymphocyte activation and diabetogenic T lymphocyte induced cytotoxicity. Finally, we determined that EndoC-βH5 cells express functional glucagon (GCG) receptor, which contributes to the modulation of glucose induced insulin secretion, highlighting the potential of EndoC-βH5 as a model to study dual and triple GLP-1/GIP/GCG receptor agonists in a reproducible human cellular model. Overall, EndoC-βH5 cells appear to be a powerful tool to develop Type 1/2 diabetes and drug discovery models.

Disclosure
H.Olleik: None. B.Blanchi: Employee; Human Cell Design.
1757-P: δ-α Cell-to-Cell Interaction Modulates Pancreatic Islet Ca2+ Oscillation Modes
Authors: REN HUIXIA 
Published: June 2023

Glucose-stimulated pancreatic islets show α cell mass dependent fast and slow Ca2+ oscillations. It implicates structure-function relationship is a fundamental principle of pancreatic islets. Despite the low percentage within the islet, the δ cells entangle with α cells and occupy the islet periphery, to envelop the β cells in the core. However, the contribution of the extensive δ-α paracrine organization to the origin of the variability in Ca2+ activation, remains unclear. Here we found that somatostatin’s perturbation on Ca2+ oscillation critically depended on α cell mass. Furthermore, pharmacological and opto-geneticalperturbation on δ-α cell interaction cause islets to repeatably show fast and slow Ca2+ oscillations. Our study highlights the importance of δ-α cell interactions as the origin of the variability in oscillation pattern. Studying islets in their intact pancreas morphology in tissue slice revealed that glucose recruited the δ cells to control the α and β cell activity.

Disclosure
H.Ren: None.
1758-P: Intracellular Metabolic Change in Rodent Pancreatic ß-Cells under Diabetic Condition Is Flexible and May Compensate for Glucose Intolerance
Authors: CHIBA KOKI , NOMOTO HIROSHI , IZUMIHARA RIMI , KAMEDA HIRAKU , MIYOSHI HIDEAKI , NAKAMURA AKINOBU , ATSUMI TATSUYA 
Published: June 2023

Background: In pancreatic β-cells under diabetic conditions, metabolic stressors cause mitochondrial dysfunction and reduce oxidative phosphorylation, resulting in impaired intracellular metabolism. It has been suggested that aberrant activation of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) plays a role in this impairment. However, the pathological significance of PFKFB3 activation and its flexibility are not clear.
Methods: Eight-week-old ob/ob mice were fed a standard chow ad lib or the same diet restricted to 2 g/day, or tofogliflozin added chow ad lib for 4 weeks. The body mass and glucose tolerance were compared among the groups. The expression of glycolytic enzymes in the pancreatic islets was evaluated using western blotting, immunohistochemistry and DNA microarray analysis. Next, INS-1 cells were cultured in medium containing a low (5.5 mM; low-G) or a high (22 mM: high-G) glucose concentration, or high-G with PFKFB3 inhibiter (3PO) for 48 hours. The expression of mafa and pdx-1 were evaluated using real time PCR.
Results: Ad lib-fed mice showed hyperglycemia and greater weight gain than food restricted mice and tofogliflozin treated mice. The expression of PFKFB3 and other glycolytic enzymes were higher in ad lib-fed mice, whereas such aberrant expression were suppressed by restricted feeding and tofogliflozin. DNA microarray analysis revealed increased expression of genes related to glycolytic pathway in ad lib-fed mice. However, these changes were corrected in a restricted diet and tofogliflozin groups. In INS-1 cells, high-G caused elevated pfkfb3 and decreased mafa and pdx-1 expression compared with low-G exposure. Inhibition of glycolytic pathway by 3PO in high-G environment did not normalize the defect of mafa and pdx-1.
Conclusion: The intracellular metabolic changes in pancreatic β cells associated with obesity and diabetes are flexible and may compensate for glucose intolerance.

Disclosure
K.Chiba: None. H.Nomoto: Speaker's Bureau; Novo Nordisk, Sumitomo Pharma, Co., Ltd. R.Izumihara: None. H.Kameda: None. H.Miyoshi: Research Support; Abbott, LifeScan Diabetes Institute, Taisho Pharmaceutical Holdings Co., Ltd., Speaker's Bureau; AstraZeneca, Boehringer Ingelheim Japan, Inc., Eli Lilly Japan K.K., Kowa Company, Ltd., MSD Life Science Foundation, Novo Nordisk, Ono Pharmaceutical Co., Ltd., Sanofi K.K., Mitsubishi Tanabe Pharma Corporation. A.Nakamura: Research Support; Abbott Japan Co., Ltd., Boehringer Ingelheim Japan, Inc., Daiichi Sankyo, Taisho Pharmaceutical Holdings Co., Ltd., Teijin Pharma Limited, Kowa Company, Ltd., Mitsubishi Tanabe Pharma Corporation. T.Atsumi: Speaker's Bureau; Eli Lilly Japan K.K., Kowa Company, Ltd.
176-OR: CopenFast Trial—Fetal Growth and Glycemic Control in Pregnant Women with Type 1 or Type 2 Diabetes Using Faster-Acting Insulin Aspart or Insulin Aspart—A Randomized Controlled Trial
Authors: NOERGAARD SIDSE K. , MATHIESEN ELISABETH R. , NØRGAARD KIRSTEN , CLAUSEN TINE D. , SØHOLM JULIE , HOLMAGER PERNILLE , DO NICOLINE C. , DAMM PETER , RINGHOLM LENE 
Published: June 2023

Aim: To evaluate the effect of faster-acting insulin aspart (faster aspart) vs. insulin aspart (IAsp) on fetal growth and glycemic control in pregnant women with type 1 or type 2 diabetes.
Methods: In a single-center, open-label trial from November 2019 to May 2022 women were stratified by diabetes type and insulin treatment modality (multiple daily injections or insulin pump) and randomized to faster aspart or IAsp from 8 to 13 weeks. Primary outcome was offspring birthweight standard deviation (SD) score. Secondary outcomes included mild hypoglycemia (managed by the woman) in the previous week, HbA1c at inclusion, 21, 33, and 35 weeks, and severe hypoglycemia (requiring third party assistance) reported in a structured interview.
Results: In total, 216 women were included and randomized to faster aspart or IAsp (n=109 vs. n=107). Baseline data were comparable in both groups. Primary outcome data were available in 94% (71% type 1 (of which 19% on insulin pump), 29% type 2 diabetes). Offspring birthweight SD score was median 0.7 (interquartile range -0.3-2.0) vs. 1.1 (0.4-1.9), mean difference -0.2 (95% confidence interval -0.6-0.1), p=0.23 with 41% vs. 46% large for gestational age infants (p=0.39). From randomization to delivery 1 (1%) vs. 7 (7%) women reported severe hypoglycemia (p=0.07) with fewer events reported by women using faster aspart compared to IAsp (1 vs. 10 events, p=0.03). At 33 weeks, women using faster aspart reported fewer mild hypoglycemic events in the previous week compared to IAsp (2.0 (0.8 - 4.0) vs. 3.0 (1.0 - 5.0), p=0.03), while HbA1c was 41 (38-46) vs. 43 (39-46) mmol/mol, p=0.28. Prevalence of preeclampsia was 15% vs. 12% (p=0.51) and preterm delivery &lt;37 weeks 19% vs. 22% (p=0.64). No perinatal deaths were reported.
Conclusion: In pregnant women with type 1 or type 2 diabetes, use of faster aspart resulted in comparable fetal growth and HbA1c with less severe hypoglycemia compared to IAsp.

Disclosure
S.K.Noergaard: Research Support; Novo Nordisk A/S. E.R.Mathiesen: Advisory Panel; Novo Nordisk, Research Support; Novo Nordisk, Speaker's Bureau; Novo Nordisk. K.Nørgaard: Advisory Panel; Medtronic, Novo Nordisk, Research Support; Medtronic, Dexcom, Inc., Novo Nordisk, Zealand Pharma A/S, Speaker's Bureau; Medtronic, Novo Nordisk, Stock/Shareholder; Novo Nordisk. T.D.Clausen: None. J.Søholm: Research Support; Novo Nordisk A/S. P.Holmager: None. N.C.Do: Research Support; Novo Nordisk Foundation. P.Damm: Other Relationship; Novo Nordisk A/S. L.Ringholm: Research Support; Novo Nordisk A/S.

Funding
Novo Nordisk A/S (U1111-1209-6358)
1762-P: Increased Glucose Sensing and Insulin Secretion Induced by Verapamil Is Associated with Enhanced Oxygen Consumption Rate in MIN6 ß-Cells
Authors: AREFANIAN HOSSEIN , BAHMAN FATEMAH , AL MADHOUN ASHRAF , ALZAID FAWAZ , SINDHU SARDAR T. , WILLIAMS MICHAYLA R. , ALRASHED FATEMA , NIZAM RASHEEBA , JACOB SINDHU , JOHN SUMI E. , ALHUSAYAN MOHAMMED , KURIAN SHIBU J. , ABUKHALAF NERMEEN A. , SHENOUDA STEVE , ALSAEED HALEMAH , KOCHUMON SHIHAB P. , ABU-FARHA MOHAMED , ABUBAKER JEHAD , THANGAVEL ALPHONSE T. , AHMAD RASHEED , ALMULLA FAHD 
Published: June 2023

It has been shown recently that oral administration of verapamil in persons with type 1 diabetes (T1D) decreased the dependency on exogenous insulin and improved the β cell function. Additionally, it decreased the frequency of hypoglycemic events. This finding encouraged us to test the effect of verapamil on the function of MIN6 mouse β cell-line. Glucose-Stimulated Insulin Secretion (GSIS) assay was performed using static incubation method. MIN6 cells were pre-treated with 50 μM verapamil for 24 hours, then the levels of total insulin content and secreted insulin were measured before and after GSIS assay using highly sensitive mouse insulin ELISA kit. Glucose sensing was estimated by the percentage of secreted insulin over total insulin content for each concentration of glucose. The measured insulin levels were normalized by the level of total protein. Oxygen consumption rate (OCR) was measured using Seahorse system and metabolic stress kit. MIN6 cells were seeded in Agilent Seahorse XF96 cell culture microplate at a cell density of 4×104 cells/well, under normal (5.6 mM) and high (25.2 mM) glucose concentrations for 24 hours, after which, cells were treated with verapamil (50 μM) or left untreated and incubated for 24 hours. Our results show no significant difference between total insulin content of treated vs. untreated cells. GSIS data show that insulin secretion was significantly higher in verapamil-treated cells at 8.4, 11.2, and 16.8 mM, but not at 2.8 and 5.6 mM glucose. The results suggest that β cells were hypersensitized to glucose when treated with verapamil. In metabolic flux analysis for mitochondrial respiration, treatment with verapamil increased basal and maximal respiration. Taken together, our study showed that verapamil increased the level of glucose sensing and oxidative respiration under conditions of high glucose, which may explain its effect on lowering the frequency of hypoglycemic events in clinical studies.

Disclosure
H.Arefanian: None. S.E.John: None. M.Alhusayan: None. S.J.Kurian: None. N.A.Abukhalaf: None. S.Shenouda: None. H.Alsaeed: None. S.P.Kochumon: None. M.Abu-farha: None. J.Abubaker: None. A.T.Thangavel: None. F.Bahman: None. R.Ahmad: None. F.Almulla: None. A.Al madhoun: None. F.Alzaid: None. S.T.Sindhu: None. M.R.Williams: None. F.Alrashed: None. R.Nizam: None. S.Jacob: None.

Funding
Kuwait Foundation for the Advancement of Sciences (RACB-2019-001)
177-OR: Worsening Insulin Resistance Is Key Pathological Contributor to Dysglycemia in Lean Koreans—A Longitudinal Validation Study in the Korean Genome and Epidemiology Study (KoGES)
Authors: KIM DOOHWA , KIM JINMI , IM MYUNGSOO , RYANG SOREE , YI WOOK , KIM MINSOO , JIN KIM YEONG , JOO KIM IN , JIN KIM YOUNG , KANG HYUK , SHERMAN ARTHUR , CHUNG STEPHANIE T. , SOO KIM SANG , HA JOON 
Published: June 2023

Insulin resistance (IR) is a modest but important pathophysiological factor in the development of type 2 diabetes (T2D) in East Asians and manageable through lifestyle intervention. The degree to which worsening insulin resistance independent of beta cell dysfunction, contributes to diabetes progression in lean Koreans is unknown. With a 10-year longitudinal study from a Korean cohort, we investigated whether worsening insulin resistance contributes to disease progression in individuals who had normal glucose tolerance at baseline (N=3700, Age=50.1±8.3 y, BMI= 24.1±2.9 kg/m2). We identified metabolic characteristics of progressors and non-progressors to prediabetes (PreDM) or T2D at baseline and 10 year-longitudinal changes in IR and BMI. To assess whether longitudinal changes of IR, independent of beta-cell function (BCF), contributed to progression, the cohort was divided into low and high BCF groups, using group median at baseline. Progressors to PreDM or T2D had weaker BCF and more insulin resistance, compared to non-progressors (Panel A) at baseline. Insulin sensitivity declined more, 30.7 vs 46.5 vs 16.7% and BMI increased in progressors to PreDM or T2D, but not in nonprogressor (Panels A and B). Conclusion: Worsening insulin resistance even for lean people is a key pathological factor to PreDM and T2D progression.

Disclosure
D.Kim: None. H.Kang: None. A.Sherman: None. S.T.Chung: None. S.Kim: None. J.Ha: None. J.Kim: None. M.Im: None. S.Ryang: None. W.Yi: None. M.Kim: None. Y.Kim: None. I.Kim: None. Y.Kim: None.

Funding
Busan Economic Promotion Agency; National Research Foundation of Korea (2022H1D3A2A01063552); Korea Health Industry Development Institute (HI18C2383); dkNET New Investigator Pilot Program in Bioinformatics; National Institute of Diabetes and Digestive and Kidney Diseases
1777-P: Three-Dimensional Imaging Reveals Pancreatic Islet Fast Calcium Wave Origin Formation
Authors: YU YI 
Published: June 2023

Pulsatile insulin secretion triggered by global calcium waves within pancreatic β cells is essential to blood glucose homeostasis. The calcium wave propagation forms by gap junction coupling among beta cells, but the emergence of wave origins is still unclear. We developed a 3D islet calcium imaging system and adapted data processing methods to observe and analyze islet calcium wave propagation quantitatively. A global fast-traveling calcium wave identifies in all kinds of oscillation modes. The calcium waves could initiate by multiple conserved β-cell clusters. We showed that the beta cell subpopulation, which first responded to high glucose stimulation, would partially contribute to calcium wave origin formation. To determine whether the spatial distribution of alpha or delta cells affects wave origin formation, we developed transgenetic mice that all islet cells were directly labeled with GCaMP6f, and alpha cells or delta cells were marked with tdTomato by Cre-Loxp strategy. Our data suggested that delta cells in the periphery modulated wave origins by electrical coupling and inhibitory paracrine interaction. Population oscillator models based on natural islet 3D structures reproduce the wave propagation observed in experiments. Interestingly, 3D imaging showed only local calcium wave bursts in ob/ob mice islets, and Immunofluorescence staining showed those sporadic bursts also correlated to delta cells.

Disclosure
Y.Yu: None.