bluuebunny/crossref_metadata_2025_split huggingface dataset:
1740-P: Regulation of Endocrine Cell Alternative Splicing Revealed by Single-Cell RNA Sequencing in Type 2 Diabetes
Authors: WANG JIN , WEN SHIYI , CHEN MINQI , XIE JIAYI , SHI GUOJUN 
Published: June 2023

The prevalent RNA alternative splicing (AS) underlies molecular diversity, which has been demonstrated in regulating cellular functions and diseases. However, the contribution of AS in pancreatic islets remains unclear during diabetes progression. Here, we reanalyzed the full-length single-cell RNA sequencing data from the deposited database to investigate AS regulation across human pancreatic endocrine cell types in nondiabetic (ND) and type 2 diabetes (T2D) individuals. Our analysis demonstrated the significant association between AS profiles and cell-type-specificity, which could be applied to distinguish the clustering of major endocrine cell types. Moreover, AS profiles were enabled to clearly define the mature subset of β-cells in healthy controls, which was completely lost in T2D. Further analysis revealed that RNA-binding proteins (RBPs), hnRNPs and FXR1 family proteins were predicted to induce the functional impairment of β-cells through regulating AS profiles. Finally, trajectory analysis of endocrine cells suggested the β-cell identity shift through dedifferentiation and transdifferentiation of β-cells during the progression of T2D. Together, our study provides a new mechanism for regulating β-cell functions and suggests the significant contribution of AS program during diabetes.

Disclosure
J. Wang: None. S. Wen: None. M. Chen: None. J. Xie: None. G. Shi: None.
1760-P: Mining Animal Venoms as a Source of Insulinotropic Peptides for Potential Diabetes Therapy
Authors: HUI JIN NG NATASHA , YEOW KOH CHO , CHING CARMEN , GOPALAKRISHNAKONE PONNAMPALAM , TEO ADRIAN 
Published: June 2023

T2D development and progression is widely known to be caused by pancreatic beta cell dysfunction, whether in the presence or absence of insulin resistance. There are however limited diabetes drugs that directly target the beta cell. Hence, there is a need to discover yet untapped pathways to increase or rescue beta cell function. Animal venoms provide a rich resource of bioactive compounds, many of which are highly potent and selective. Venom peptides have been harnessed for therapeutic drug development, such as the blockbuster diabetes drug, exenatide, a GLP-1 receptor agonist, being a synthetic form of exendin-4 that was first isolated from the saliva of the Gila monster. We hypothesize that we can further discover and develop new therapeutic agents that promote pancreatic beta cell function based on venom-derived compounds. We studied up to seven animal venoms from snakes, bees and scorpions. Pancreatic beta cells (including EndoC-βH1 cells, human islets, and MIN6 cells) were treated with crude animal venoms from each species and evaluated for insulin secretion capacity. We used a range of doses that elicit insulin secretion without causing cellular damage. Venoms from Apis mellifera (honey bee) and Naja naja (Indian cobra) were shown to robustly stimulate insulin secretion in a dose-dependent manner without affecting cell viability. Treatment with these venoms were also able to rescue diabetic cell models. We prioritized these two venoms for fractionation via gel filtration and reverse phase HPLC. After subsequent screening of the venom sub-fractions in insulin secretion assays, we pinpointed specific sub-fractions responsible for stimulating insulin release. Ongoing work is in progress to identify and validate selected peptides for insulinotropic activity, safety and stability. The insulinotropic peptides (and any modifications) may represent new therapeutic strategies for tackling T2D in future.

Disclosure
N.Ng: Stock/Shareholder; BetaLife. C.Koh: None. C.Ching: None. P.Gopalakrishnakone: None. A.Teo: None.

Funding
A*STAR Career Development Fund (202D800020)
1764-P: Assessing Gene Expression Profile and Insulin Secretion in Human Beta Cells (EndoC-BH3) under Glucose Exposure
Authors: MULLER YUNHUA L. , WIEDRICH KIMBERLY , SUTHERLAND JEFF , JONES DARTANYON , BAIER LESLIE 
Published: June 2023

Maternal diabetes is a risk factor for type 2 diabetes in the offspring, and in utero exposure to high glucose has been shown to affect pancreatic beta cell development in animal models. However, the developmental stage and specific genes which underlie these effects in humans are unknown. We aimed to understand the consequences of high glucose on the fetal pancreas by treating a human beta cell line derived from fetal pancreas, EndoC-BH3, with high, medium and normal glucose (30, 15 and 5.5mM respectively) for 3 weeks during proliferation and maturation and comparing gene expression using whole transcriptome analysis. The top differentially expressed transcripts (P&lt;10−4) and the most abundant transcripts (Log2 unit&gt;10.5) were validated by real-time RT-PCR. KEGG analyses of the top 500 differentially expressed transcripts identified the metabolic pathway as the top pathway. Among individual genes, high glucose exposure during the maturation upregulated EGR1 (58.6-fold), BIRC5 (37.6-fold), GPBAR1 (15.4-fold), G6PC2 (11.8-fold), CHRNA (4.8-fold), GCK (2.7-fold), INS (2.0-fold), CMIP (1.9-fold) and CHGA (1.4-fold) as compared to normal glucose exposure. EGR1 encodes early-growth response 1, a transcription factor that enhances insulin gene expression, while BIRC5 encodes an apoptotic inhibitor that plays a role in beta cell proliferation. High glucose exposure during the proliferation identified similar differentially expressed genes; however, the changes were more modest as compared with the maturation. Methylation has also been implicated in conveying risk for diabetes due to glucose exposure and several key DNA demethylation enzymes; TET1, 2, 3, were also moderately upregulated. Assessment of the effects of glucose exposure on insulin secretion and total insulin content is ongoing. Our data suggest that short term exposure to high glucose may stimulate expression of a set of genes that promote beta cell proliferation and insulin expression and secretion.

Disclosure
Y.L.Muller: None. K.Wiedrich: None. J.Sutherland: Stock/Shareholder; Pfizer Inc., Bristol Myers. D.Jones: None. L.Baier: None.
177-LB: Association of Pregnancy and Childhood C-Peptide Levels—Hyperglycemia and Adverse Pregnancy Outcome Follow-up Study (HAPO-FUS)
Authors: ZHENG HAO , RAJAMOORTHI ANANTHI , SKOWRONSKI ALICJA , SALEM RANY , LEDUC CHARLES A. , THAKER VIDHU V. 
Published: June 2023

Physiological insulin resistance partitions glucose for the growing fetus during the 2nd and 3rd trimester of pregnancy. The HAPO study has demonstrated that pregnancy hyperglycemia is associated with offspring adiposity, hyperglycemia, and glucose intolerance. Maternal insulin is a key regulator of the glucose physiology but does not cross the placenta. The goal of this study was to identify the association of pregnancy and offspring c-peptide levels, measured during oral glucose tolerance test (OGTT).
Method: Using HAPO-FUS data from the NIH-NIDDK repository, multiple linear regression assessed the association of scaled pregnancy fasting and 1-hour c-peptide with cord c-peptide (at birth), and child c-peptide from OGTT at the follow-up visit (ages 10-14 years). Maternal covariates include pregnancy gestational age, BMI, glucose level and field center. Child covariates include age, sex, tanner stage, BMI z-score and glucose level. Multiple imputation was performed using missing at random assumption.
Results: A total of 4,802 mother-child pairs were included. Pregnancy c-peptide was associated with cord c-peptide (fasting 0.02 [0.01-0.03], p &lt;.001, 1-hour 0.01 [0.002-0.02], p =.006). Pregnancy fasting c-peptide was also associated with child OGTT c-peptide (fasting 0.03 [0.02-0.04], p &lt;.001; 1-hour 0.11 [0.08-0.15], p &lt;.001; 2-hour 0.01 [0.007-0.02], p &lt;.001) and pregnancy 1-hour c-peptide (fasting 0.01 [0.007-0.02], p &lt;.001; 1-hour 0.15 [0.12-0.17], p &lt;.001; 2-hour 0.11 [0.09-0.14], p &lt;.001). Similar associations were observed with child insulin levels. Pregnancy c-peptide levels were positively associated with HOMA-IR and negatively with child insulin sensitivity and Matsuda index while adjusting for child BMI z-score and pubertal stage.
Conclusion: Pregnancy insulin levels are strongly associated with the child insulin response during OGTT. This suggests a role in the offspring pancreas developmental programming.

Disclosure
H. Zheng: None. A. Rajamoorthi: None. A. Skowronski: None. R. Salem: Other Relationship; Travere Inc. C. A. Leduc: None. V. V. Thaker: None.

Funding
National Institutes of Health (K23DK110539)
1772-P: Alpha-Cell Heterogeneity Contributes to Phasic Glucagon Release
Authors: MIRANDA CAROLINE A. , DOU HAIQIANG , TOLÖ JOHAN , TARASOV ANDREI I. , RORSMAN PATRIK 
Published: June 2023

Glucagon, produced by α-cells of pancreatic islets, is one of the body’s primary tools for elevating blood glucose during hypoglycemia. The exact mechanism linking hypoglycemia to glucagon release by islet α-cells is, however, unclear; we therefore aimed to investigate it using optogenetics. We generated mice harboring the light-activated ion channel channelrhodopsin-2 (ChR2) specifically in α-cells and imaged the effect of optically induced depolarization of plasma membrane (10-ms 470-nm light pulses at 20Hz) at the level of membrane potential, cytosolic Ca2+ ([Ca2+]i) and ATP/ADP ratio. At 1 mmol/L glucose, optostimulation depolarized the electrically active α-cells from -76mV to -8mV, induced a transient surge in [Ca2+]i and elevated glucagon secretion by 200%. In contrast, the glucagonostatic effect of high glucose (&gt;6 mmol/L) was mitigated by optostimulation of α-cells. At 1 mmol/L glucose, the stimulatory effects were abolished by the KATP channel activator diazoxide (100μmol/L) and L-type Ca2+ channel blocker isradipine (10μmol/L). Notably, KATP channel inhibitor tolbutamide (100μmol/L) induced electrical activity in the fraction of α-cells insensitive to low glucose (35%). As stimulation of electrical activity persisted significantly beyond optoactivation, we probed the interplay between electrical activity and energy metabolism. The depolarizing stimulus induced by a cocktail of amino acids ((AA) 2 mmol/L of alanine + arginine +glutamine) or a moderate increase of extracellular K+ (from 4 to 15 mmol/L) reduced ATP/ADP in α-cells exhibiting spontaneous Ca2+ oscillations at low glucose. Surprisingly, in the population of inactive α-cells, the stimulation increased ATP/ADP ratio. These data indicate that α-cells are functionally heterogeneous due to metabolic differences. The observed secretory responses reflect the combination of stimulatory and inhibitory effects in electrically active and silent cells, which may contribute to the phasic nature of AA-induced glucagon secretion.

Disclosure
C.A.Miranda: None. H.Dou: None. J.Tolö: None. A.I.Tarasov: None. P.Rorsman: None.

Funding
Svenska Sällskapet för Medicinsk Forskning (PD20-0056); Swedish Vetenskap Rådet
1781-P: Leptin Regulates Delta-Cell Somatostatin Secretion from Human and Mouse Islets
Authors: HARTIG SEAN M. , COX AARON 
Published: June 2023

The delta cell is uniquely positioned in the islet to integrate local signals and circulating nutrient cues to regulate alpha and beta cell function through somatostatin (SST) secretion. In type 2 diabetes (T2D), delta cell responses to ambient glucose are disproportionate and consequently alter insulin and glucagon secretion leading to dysglycemia. However, we know relatively little about the mechanisms influencing delta cells. Thus, understanding factors that regulate delta cell SST secretion may reveal pathogenic mechanisms contributing to T2D and direct new therapies to achieve glucose homeostasis. Leptin is a circulating hormone that potently inhibits insulin and glucagon secretion, but notably, the leptin receptor (LepR) is exclusively expressed on delta cells of human islets. Our preliminary studies demonstrate for the first time that leptin stimulates SST secretion from human islets. Leptin-induced SST corresponded with decreased glucagon and insulin secretion. Leptin effects were conserved in mouse islets and required delta cell specific LepR expression. Our single-cell RNA-seq studies revealed Stat3 target genes become depleted in delta cells that lack LepR, suggesting canonical leptin signals regulate transcriptional activity in delta cells. Along these lines, delta cell specific Stat3 KO islets (Sst-Cre+/wt;Stat3fl/fl) do not respond to leptin. On-going studies in human islets employ pharmacologic and genetic interventions with live functional imaging and unbiased approaches that will reveal the mechanisms of leptin action in human delta cells. These studies are the first to describe leptin effects on delta cells and uncover a unifying mechanism whereby leptin acts indirectly on alpha and beta cells through paracrine SST signaling. As such, our findings are expected to reveal new signaling mechanisms governing islet function that potentially exert therapeutic benefits for T2D.

Disclosure
S.M.Hartig: None. A.Cox: None.
18-LB: Branched-Chain Amino Acids, Acyl-carnitines, and Purine Metabolism Are Associated with Glycemic Variability after Coronary Artery Bypass Graft Surgery
Authors: GUERRERO ARROYO LIZDA I. , ZAHEDI TAJRISHI FARBOD , PEREZ-GUZMAN MIREYA , SAM VARGHESE JITHIN , ABRAHAM AMALIA , SMITH MATTHEW R. , PASQUEL FRANCISCO J. 
Published: June 2023

Many patients without diabetes who undergo CABG surgery experience high glycemic variability in the postoperative period. However, the underlying mechanisms associated with glycemic variability after surgery are unknown. We used prospective observational data from 17 patients without diabetes who underwent CABG surgery and wore a Dexcom G6 pro CGM device during the perioperative period. We estimated the coefficient of variation [CV] using CGM values calibrated to point-of-care measurements. We categorized patients into high variability (CV &gt; 10%; n = 5) and low variability (CV ≤ 10%; n = 12) during the first 24 hours after surgery. Metabolic pathways were identified from HILIC positive and Reverse Phase C18 analysis, with metabolites mapped to Kyoto Encyclopedia of Genes and Genomes (KEGG) human pathways using mummichog. Baseline clinical characteristics were similar between the groups. Branched-chain amino acid (BCAA) (e.g. isovalerylglutamic acid), lipids (e.g. acylcarnitine), and purine metabolism (e.g. cGMP) were associated with glycemic variability in the perioperative period, Figure. Metabolomics analysis suggests BCAA, acylcarnitines, and purine pathway metabolites are associated with glycemic variability after CABG surgery.

Disclosure
L. I. Guerrero arroyo: None. F. Zahedi tajrishi: None. M. Perez-guzman: None. J. Varghese: None. A. Abraham: None. M. R. Smith: None. F. J. Pasquel: Consultant; Dexcom, Inc., Medscape, Research Support; Dexcom, Inc., Ideal Medical Technologies.

Funding
National Institutes of Health (K23GM128221); Dexcom, Inc.
181-LB: Congenital Malformations and Medication Use in Women With Type 2 Diabetes—Preliminary Results
Authors: REICHELT ANGELA A.J. , GUERRA GIULIA L. , DE CAMPOS MARIA A. , HIRAKATA VÂNIA N. , OPPERMANN MARIA LUCIA R. 
Published: June 2023

Background: Congenital malformations occur more frequently in pregnancies of women with type 2 diabetes, mainly attributed to poor glycemic control. However, using certain medications may also contribute. Aim: To describe medication use by conception time in women with type 2 diabetes.
Methods: In this retrospective cohort, women with singleton pregnancies from two tertiary care hospitals were enrolled. Data on maternal age, time of diabetes diagnosis, medication use, BMI, HbA1c, and congenital malformations were collected from medical records between May 2005 and June 2021. We excluded four neonates with genetic/chromosomic diseases. Poisson regression with robust estimates was used to evaluate risk factors for congenital malformations.
Results: We included 634 women; 212 (33.5%) presented overt diabetes; 136 (21.5%) arrived at prenatal care in the first trimester; 18 (2.8%) had a miscarriage; 560 (88.3%) delivered alive newborns, and 17 (2.7%), stillbirth. Only 227 women (35.8%) had an HbA1c measured in the first trimester, and 304 (48.6%) had an HbA1c before 28 weeks of gestation. Congenital malformations were diagnosed in 77 (13.7%) neonates; of these, 56 (73%) were cardiac defects, isolated or combined with other malformations. Few women used folate in the first trimester (115; 18.1%), almost always introduced after pregnancy diagnosis; 353 (55%) used oral antidiabetics; 116 (18.3%), any anti-hypertensive medication, and 16 (2.5%), statins. In adjusted models including age, BMI and HbA1c, sulfonylurea was associated with increased risk of congenital malformation: RR 2.7, 95% CI 1.3-5.6, p=0.009, when HbA1c in the first trimester entered the model (n=200); and RR 1.64, 95% CI 1.0-2.6, p=0.038, with an HbA1c measured before 28 weeks (n=539).
Conclusion: In this cohort of women with type 2 diabetes, congenital malformations were more frequent than in the general population. Sulfonylurea was the only medication associated with an increased risk of congenital malformation.

Disclosure
A. A. J. Reichelt: None. G. L. Guerra: None. M. A. De campos: None. V. N. Hirakata: None. M. R. Oppermann: None.

Funding
FIPE-HCPA (2016-0331)
195-OR: To Which Degree Do Alpha Cells Shape the Role of the Beta Cells First Responders?
Authors: KRAVETS VIRA , LEVITT CLAIRE H. , BENNINGER RICHARD K. 
Published: June 2023

Calcium (Ca2+) uptake drives glucose-stimulated insulin secretion from the pancreatic β-cells. The “1st responder” subpopulation of β-cells disproportionally control the Ca2+ uptake during the first phase, which is disrupted with ageing and in diabetes. Here we determine whether alpha and delta cells play a formative role in the 1st responder β-cells state. We used MIP-CreER GCaMP6s mouse model which expresses Ca2+-sensitive GFP specifically in β-cells. We performed simultaneous recording of Ca2+ dynamics and gap junction permeability in individual islets. We stimulated islets with glucose, and with the GLP1-R antagonist, exendin 9-39 (Ex9). Based on the first-phase Ca2+ dynamics we defined the “1st responder” and the “last responder” cells. We tested their consistency under repeated glucose stimulation with and without the Ex9. We next stained them for insulin, glucagon, and somatostatin and measured distances in 3D from all β-cells to alpha and delta cells. The Ex9 disrupted the 1st responder consistency (only half of the original 1st responders remained such under repeated glucose stimulation), compared to the control experiment. Ex9 increased the islet's first-to-last cell response time by 150 +/- 74 seconds making islet's response to glucose two times more heterogeneous compared to control (p=0.0517). On average 1st responders were located closer to the alpha cells, and last responders - further from them (p=0.0039). At the same time, first responders had significantly less delta cell neighbors compared to the last responders (p=0.0137). Our gap junction permeability data showed no gap junction activity in alpha-beta cell couples. In conclusion, 1st responder beta cells have more alpha cell and less delta cell neighbors than last responders. The role of the alpha cell in the formation of the 1st responder cell state is likely realized via paracrine interaction.

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

Funding
Burroughs Wellcome Fund (25B1756 to V.K.); National Institutes of Health (R01DK102950, R01DK106412 to R.K.B.); Human Islet Research Network (UC24DK104162 to V.K.)
2-OR: Risk Factors for Continuous Glucose Monitoring (CGM)-Detected Hypoglycemia in Very Old Adults with Type 2 Diabetes
Authors: FANG MICHAEL , JEON YEIN , CORESH JOSEF , ECHOUFFO TCHEUGUI JUSTIN , ZEGER SCOTT L. , SELVIN ELIZABETH 
Published: June 2023

Introduction: Risk factors for hypoglycemia in very old adults with type 2 diabetes are uncharacterized. CGM identifies biochemical hypoglycemia but is not widely used in type 2 diabetes.
Methods: We conducted a cross-sectional analysis of 282 adults with type 2 diabetes (mean age 84 years; 32% using insulin or sulfonylureas [SUs]) in the Atherosclerosis Risk in Communities study (2021-2022). Participants wore the Abbott Libre Pro monitor (blinded) for up to 14 days. We examined the percentage of time participants had glucose readings &lt;70 mg/dl (T&lt;70), stratified by medication use. We considered T&lt;70 separately during daytime (6:00AM-11:59 PM) and overnight (12:00AM-5:59 AM).
Results: There was substantial hypoglycemia in very old adults using insulin or SUs, especially overnight (median T&lt;70: 5.1%) (Figure). In this population, females and those with cardiovascular disease, poor physical functioning, or a prior history of severe hypoglycemia experienced the most overnight hypoglycemia. T&lt;70 was low in those not using insulin or SUs, but those with dementia were at an increased risk for overnight hypoglycemia.
Conclusion: Cardiovascular disease, functional impairment, and prior severe hypoglycemia were major risk factors for nocturnal hypoglycemia in very old adults using insulin or SUs. The benefits of CGM should be explored for these patients.

Disclosure
M.Fang: None. Y.Jeon: None. J.Coresh: Consultant; Healthy.io Ltd, SomaLogic. J.Echouffo tcheugui: None. S.L.Zeger: None. E.Selvin: None.