bluuebunny/crossref_metadata_2025_split huggingface dataset:
1512-P: Brown Adipose NMNAT1 Is Necessary for Maintaining NAD+ Levels but Dispensable for Systemic Energy Metabolism
Authors: SHEN XIYU , SONG WON-SUK , CAO YANG , JIAO XINFENG , ZHU YUAN , JANG CHOLSOON , YANG QIN 
Published: June 2024

Brown adipose tissue (BAT) is rich in mitochondria and expresses high levels of uncoupling protein 1 (UCP1), enabling it to regulate thermogenesis and system energy expenditure. NAD+ (nicotinamide adenine dinucleotide) is a key cofactor for maintaining mitochondrial function by serving as a redox carrier and signaling molecule. To investigate the regulation and function of NAD+ in BAT, we measured the expression of genes involved in NAD+ synthesis and catabolism in mice under room temperature, cold challenge, and thermoneutral conditions. We found that the expression of nicotinamide nucleotide adenylyltransferase 1 (NMNAT1), the final enzyme for NAD+ synthesis, was suppressed by thermoneutrality and increased by cold challenge in BAT. We, therefore, generated brown adipocyte-specific NMNAT1 knockout mice (NMNAT1-bKO) by crossing the NMNAT1 flox/flox mice to the UCP1-Cre mice. NMNAT1 deletion reduced NAD+ levels by approximately 50%, accompanied by the accumulated precursors, including NMN and NaMN in BAT. Despite the significant reduction of BAT NAD+, NMNAT1-bKO mice showed comparable body weight, normal glucose tolerance and insulin sensitivity, and unchanged systemic energy metabolism, including O2 consumption, CO2 production, and RER in the metabolic cage studies. Further cold challenges and high-fat diet feeding did not induce any differences in the metabolic phenotype. RNA-seq analysis of BAT from NMNAT1-bKO and control mice under cold challenge revealed enrichment of genes involved in mitochondrial function and lipid metabolic process. These results show that BAT NMNAT1 is necessary for maintaining NAD+ levels but dispensable for systemic energy metabolism, possibly due to compensatory upregulation of mitochondrial genes.

Disclosure
X. Shen: None. W. Song: None. Y. Cao: None. X. Jiao: None. Y. Zhu: None. C. Jang: None. Q. Yang: None.

Funding
National Institutes of Health (R01DK121146)
1513-P: Physiological Level of Fructose Together with Glucose Promotes Brown Adipogenesis and Facilitates Fatty Acid Transport and Metabolism in Differentiated Mouse Brown Adipocytes
Authors: WU XIANGDONG , ELSAID SALAHELDEEN A.A. , SENG TEE SUI 
Published: June 2024

Because of its thermogenic property in response to cold and overnutrition, brown adipose tissue in adult humans has become an attractive therapeutic target for treatment of obesity, atherosclerosis and other metabolic syndromes. It is unknow if fructose impacts adipogenesis, metabolism and functions of brown adipocytes. To address the question, we isolate brown preadipocyte from newborn mouse pups, immortalized the cells, and differentiated cells in culture medium with different sugars (1g/L glucose, 1g/L glucose plus 1g/L fructose, 1g/L fructose). Fructose plus glucose increased expression of adipogenesis markers including PPAR-γ, UCP-1 and C/EBP1. Fructose alone decreased adipogenesis proteins. Moreover, fructose alone increased CD36 but decreased FABP4 expression, suggesting cells need to uptake more fatty acid in compromise of carbon shortage from glucose, but fatty acid could not be effectively transported to organelles such as mitochondria, ER or Golgi because of lack of FABP4. In contrast, Fructose plus glucose increased FABP4 although it did not change of CD36, suggesting fatty acid could effectively be trafficked to organelles. Fructose plus glucose did not change phosphorylation of p38-MAPK but enhanced the phosphorylation of Erk at Thr202 and Tyr204. As to Akt, the site of Ser473 phosphorylation decreased, not at Thr308. Our data indicates physiological level of fructose together with glucose promotes brown adipogenesis, enhances thermogenic protein UCP-1, facilitates fatty acid transport and metabolisms in differentiated mouse brown adipocytes.

Disclosure
X. Wu: None. S.A.A. Elsaid: None. S. Tee: None.
1526-P: Alpha Cells Facilitate Neuronally-Stimulated Insulin Secretion at Fasting Glucose
Authors: TRIMIGLIOZZI KELLY , WIEDEMANN SOPHIA J. , MEIER DANIEL T. , BOENI-SCHNETZLER MARIANNE , DONATH MARC Y. 
Published: June 2024

Introduction: Pancreatic islets are richly innervated by parasympathetic neurons and in turn neuronal stimulation can induce insulin secretion even in the fasted state. A prime example of this neuronally-driven insulin secretion is the cephalic phase insulin response, which is the release of insulin in the anticipation of a meal and occurs prior to changes in blood glucose. We recently found IL-1b to be in an important mediator of cephalic phase insulin secretion, however the mechanisms enabling neuronally-mediated insulin release from pancreatic islets in the fasted, low glucose state are still unknown.
Methods: We treated overnight-fasted mice with exogenous glucagon pre-treated with atropine and assessed insulin secretion. Using transgenic mice in which exclusively alpha cells are ablated, we studied the contribution of glucagon in cephalic phase insulin secretion. With isolated islets of wild-type and alpha cell-ablated mice we assessed insulin and glucagon secretion at 3.5mM glucose after co-stimulation with IL-1b and a muscarinic agonist (carbachol). Further, we blocked both glucagon and GLP-1 receptors to investigate which receptor glucagon acts on in our isolated islets setting.
Results: We found that exogenous glucagon can stimulate insulin secretion and this stimulation was absent in atropine-pretreated mice. Further, alpha-cell ablated mice do not exhibit a cephalic phase insulin response. In vitro, co-stimulating islets with the carbachol and IL-1b stimulated insulin secretion at basal glucose, and this was not the case in alpha cell-ablated islets. Lastly, we found that glucagon acts both on the glucagon and GLP-1 receptor to enable carbachol and IL-1b stimulated insulin release.
Conclusion: Alpha cells are essential for cephalic phase insulin secretion and this neuronally-mediated beta-cell response relies on glucagon or GLP-1, thereby positioning alpha cells as an important facilitator of neuronally-stimulated insulin secretion at fasting glucose.

Disclosure
K. Trimigliozzi: None. S.J. Wiedemann: None. D.T. Meier: None. M. Boeni-Schnetzler: None. M.Y. Donath: Advisory Panel; Novo Nordisk, Lilly Diabetes, Boehringer-Ingelheim. Research Support; Boehringer-Ingelheim, Olatec.
1528-P: Investigate Functional Dynamics of Neuropeptides in Acute Brain Slices to Predict Anorexigenic Efficacy
Authors: PEKCEC ANTON , ALTAS BEKIR , BRUSCHETTA GIUSEPPE , BUZZANCA ANNA , DOERR JONAS , LAM DANIEL , LINCOLN KATHLEEN A. , MACK VOLKER 
Published: June 2024

Obesity represents the largest and rapidly escalating global health crisis in the world, predominantly attributed to a disequilibrium between caloric intake and energy expenditure. Contemporary therapeutic strategies predominantly employ anorexigenic peptides such as GLP-1 and GIP receptor agonists. The physiological response is mediated by specific neuronal clusters of the hypothalamus, particularly the arcuate nucleus, which harbors a complex neuronal network that plays a pivotal role in modulating satiety and hunger signaling within the brain. Therefore, elucidating the neuronal responses within the arcuate nucleus is critical for profiling novel compounds and combinations thereof, to discover innovative and more efficacious therapeutic strategies. We have established an integrated opto-neurophysiology setup that combines functional calcium imaging and electrophysiological recordings in acute brain slices of the hypothalamus. We make use of different cell labeling strategies including chemical and genetically encoded calcium indicators (GECIs) to mark neuronal populations within the arcuate nucleus, and have successfully captured distinct neuronal responses to various neuropeptides within a suitable assay window. Our platform enables sequential monitoring of individual or combined neuropeptides in vitro, allowing for differentiation on a neuronal network level. Finally, we provide evidence that the selection of differential combinations through such screening results in more efficacy in food intake and body weight loss. Therefore, this approach not only enables the in vitro profiling of compounds in acute applications but also supports suitable screening for novel combinations within the native hypothalamic or any obesity associated neuronal circuitry, thereby to achieve enhanced synergistic efficacy for anti-obesity treatment in vivo.

Disclosure
A. Pekcec: Employee; Boehringer-Ingelheim. B. Altas: Employee; Boehringer-Ingelheim. G. Bruschetta: Employee; Boehringer-Ingelheim. A. Buzzanca: Employee; Boehringer-Ingelheim. J. Doerr: Employee; Boehringer-Ingelheim. D. Lam: Employee; Boehringer-Ingelheim. K.A. Lincoln: Employee; Boehringer-Ingelheim. V. Mack: Employee; Boehringer-Ingelheim.
1530-P: Mind over Metabolism—Dorsal Vagal Neurons Can Improve Glucose Tolerance, Reduce Heart Rate, and Suppress Anxiety-Like Behavior
Authors: CONLEY NICHOLAS J. , CAMPBELL JOHN , VANDERVOORT LANE 
Published: June 2024

Parasympathetic neurons of the dorsal motor nucleus of the vagus (DMV) play a crucial role in regulating glucose metabolism via the vagus nerve, making them potential targets for diabetes treatment. We sought to identify and investigate these neurons by chemogenetically activating them in awake, behaving mice during glucose tolerance tests. We virally targeted hM3Dq receptors to DMV neurons by the co-expression of Chat- and Phox2b- driven recombinases in our transgenic mouse model (Chat-Cre;Phox2b-Flp;dsHTB mice). The experimental protocol involved recording baseline glucose levels (after fast), followed by the injection of the hM3Dq ligand, Clozapine-n-oxide (CNO), or vehicle. After a 30min wait, we administered glucose (i.p) and conducted tail blood glucometry at 5min intervals from -30min to 120min. Average blood glucose readings were compared between CNO and vehicle. Our findings indicate that activating DMV neurons significantly improves glucose tolerance 5min after glucose injection: Vehicle-5min: 276.8 ± 12.8, CNO-5min: 218.8 ± 12.0, p=0.0459, n=8 (RM two-way ANOVA with Šídák’s). To identify specific DMV neurons involved in glucose regulation, we selectively activated a molecular subtype characterized by co-expression of Calb2 and Chat. Activating Calb2+ DMV neurons with CNO also substantially improved glucose tolerance compared to vehicle at both 5- and 15-minute time points: Vehicle-5min: 281.4 ± 12.7, CNO-5min: 242.3± 8.6, p=0.0459; Vehicle-15min: 411.0 ± 14.0, CNO-15min: 335.5 ± 9.2, p=0.0016, n=16 (RM two-way ANOVA with Šídák’s). Together our data indicates that activating DMV neurons generally or Calb2+ DMV neurons specifically improves glucose tolerance. These findings identify a specific vagal motor neuron population which can control glucose tolerance and so may lead to novel therapeutics for diabetes and other metabolic disorders.

Disclosure
N.J. Conley: None. J. Campbell: None. L. VanderVoort: None.

Funding
American Diabetes Association (1-18-INI-14)
1533-P: Leptin-Sensitive Sensory Nerves Mediate Cross Talk between Interscapular Brown Adipose Tissue and Proopiomelanocortin Neurons
Authors: YANG XIAOHUA , MUNOZ MARCOS D. , LUO PEI , TORRES IRIZARRY VALERIA C. , YE HUI , CARRILLO-SÁENZ LESLIE , ANTONY NIMISHA , WEE LIEW CHONG , XU PINGWEN 
Published: June 2024

Adipose tissues communicate with the central nervous system (CNS) through secreted adiponectins, including leptin. Recent studies have shown that, in addition to its role as an endocrine hormone, leptin also communicates with the brain through leptin-sensitive spinal sensory nerves (SS) located in the L1-L3 dorsal root ganglia (DRG) that innervate white adipose tissues. Interestingly, we observed a high expression of the leptin receptor (LEPR) in the T1-T3 DRGs, which are primarily associated with interscapular brown adipose tissue (iBAT). These findings suggest that iBAT leptin may exert metabolic functions as a paracrine sensory signal. Supporting this idea, injecting a low dose of leptin into iBAT activated LEPR signaling in the T1-T3 DRG without affecting circulating levels of leptin. Additionally, it selectively stimulated LEPR-positive T1-T3 DRG neurons. These findings indicate that LEPR not only exists in iBAT-associated DRG, but also responds to leptin and mediates neuronal activation. Interestingly, infusion of leptin into the iBAT also stimulates proopiomelanocortin neurons in the arcuate nucleus of the hypothalamus (POMC/ARH). This suggests a potential crosstalk mediated by LEPR-positive SS between iBAT and POMC/ARH. The presence of this crosstalk is further supported by the anatomical connection between POMC/ARH neurons and iBAT-associated sensory nerves, as demonstrated by transsynaptic dual tracing. Importantly, the stimulatory effects of iBAT leptin infusion on ARH neurons are abolished when iBAT-associated sensory nerves are chemically ablated or when POMC/ARH neurons are genetically ablated. Taken together, our results indicate that iBAT has a structural and functional basis for paracrine leptin signaling via SS, which interacts with POMCARH neurons to regulate energy homeostasis. Keywords: Leptin; POMC; DRG; Spinal sensory nerve; Interscapular brown adipose tissue

Disclosure
X. Yang: None. M.D. Munoz: None. P. Luo: None. V.C. Torres Irizarry: None. H. Ye: None. L. Carrillo-Sáenz: None. N. Antony: None. C. LIew: None. P. Xu: None.
1541-P: The Role of Microglia Estrogen Receptor Alpha Signaling in Obesity Pathogenesis
Authors: VELASCO AGUAYO INMACULADA , JAFARI TRISTAN Z. , FREY JEREMY , SANTIAGO OLIVIA D. , THALER JOSHUA , DORFMAN MAURICIO D. 
Published: June 2024

The sex steroid estrogen reduces susceptibility to obesity and its metabolic complications by suppressing food intake, enhancing energy expenditure, improving insulin sensitivity, and reducing immune cell activation. However, the mechanisms involved remain incompletely understood. In rodents, high-fat diet (HFD) feeding is associated with increased inflammatory activation of microglia (brain myeloid cells) in the mediobasal hypothalamus (MBH), which promotes diet-induced obesity (DIO). Importantly, surgical or chemical castration exacerbates HFD-induced microglial activation, an effect reversed by estrogen replacement therapy. Therefore, we hypothesize that estrogen reduces DIO susceptibility through a cell-autonomous anti-inflammatory action on microglia via the nuclear receptor estrogen receptor alpha (ERα). To test this hypothesis, we generated a mouse model with microglia-specific deletion of ERα (MG-ERαKO). We found that MG-ERαKO male mice exposed to HFD for 15 weeks have increased weight gain and fat mass relative to control mice, attributable to a significant reduction in energy expenditure. In contrast, HFD feeding of MG-ERαKO female mice did not elicit a body weight difference with controls. Nevertheless, a small but significant reduction in insulin sensitivity was observed in both sexes of MG-ERαKO mice. Immunohistochemical analyses of MBH brain sections from MG-ERαKO mice demonstrated higher immunoreactivity for the microglial marker IBA1 along with an increase in microglial number and cell size, all indicators of a more activated cellular profile. These findings strongly support a sex-specific action of estrogen to limit the metabolic complications of HFD feeding through microglial ERα signaling.

Disclosure
I. Velasco Aguayo: None. T.Z. Jafari: None. J. Frey: None. O.D. Santiago: None. J. Thaler: Consultant; Eli Lilly and Company. M.D. Dorfman: None.
1556-P: Glucocorticoid-Induced Insulin Secretion via the Hypothalamic–Pituitary–Adrenal–Islet Axis Is Needed for Proper Body Weight Regulation and Pancreas Development
Authors: MEIER DANIEL T. , RACHID LEILA , DONATH MARC Y. 
Published: June 2024

Prohormone convertase 1/3 (PC1/3) is a protease involved in processing of various prohormones. Inactivation mutations in PC1/3 are associated with severe obesity in mice and humans. Mechanistically, it is not well understood which misprocessed hormones induce this obesity phenotype. PC1/3 processes proopiomelanocortin (POMC) into peptides that regulate body weight via modulating the melanocortin system. To shed light on this mechanism, we deleted PC1/3 from POMC-expressing tissues, thereby blocking the processing of POMC to melanocortin-stimulating hormones (MSH) and adrenocorticotropic hormone (ACTH). Surprisingly, body weight was only mildly and transiently increased in young POMC-specific PC1/3 knockout mice, however later in life a prominent underweight developed. These mice had an impaired hypothalamic-pituitary-adrenal (HPA) axis which resulted in inadequately low basal and ACTH-stimulated circulating glucocorticoid levels. Further, basal circulating insulin levels were strongly reduced and glucose tolerance impaired. In aged underweight PC1/3 knockout mice, corticosterone replacement therapy increased body weight to the level of control mice and normalized insulin levels as well as glucose tolerance. In addition, glucose-stimulated insulin secretion from isolated islets and total islet insulin content from POMC-specific PC1/3 knockout mice were reduced. In line with this, pancreas weight and beta-cell mass were reduced, suggesting that there are islet intrinsic developmental and secretory pathologies present in these mice. Our data show that insufficient levels of endogenous glucocorticoids negatively impact pancreas development and insulin secretion, and that this is associated with an impaired body weight development. All these phenotypes are reversible by steroid replacement therapy, suggesting that the HPA axis regulates body weight development via insulin secretion.

Disclosure
D.T. Meier: None. L. Rachid: None. M.Y. Donath: Advisory Panel; Novo Nordisk, Lilly Diabetes, Boehringer-Ingelheim. Research Support; Boehringer-Ingelheim, Olatec.
1561-P: Insulin Secretion Is Markedly Impaired in Young, Lean Rwandan Adults with New-Onset Type 2 Diabetes
Authors: MUGENI REGINE , SMITH GORDON I. , SUMNER ANNE E. , CADE WILLIAM T. , REEDS DOMINIC 
Published: June 2024

Introduction: 80% of cases of type 2 diabetes mellitus (T2D) occur in low- and middle-income countries and primarily afflicts lean people; the reasons for this are unclear but may relate to fat-distribution and/or pancreatic function. We aimed to: 1) compare insulin-secretion rates (ISR) between lean, (BMI &lt;25kg/m2) Rwandan adults with and without new-onset (&lt;1yr) T2D; and 2) to examine the impact of elevated WC (&lt;85cm for women and &lt;90cm for men, &gt;75th %ile of group) on ISR and insulin resistance in people with T2D.
Methods: BMI, WC, and a 3-hour frequently-sampled oral-glucose tolerance-test were performed in 23 Rwandans; 15 with T2D (7 Male) and 8 healthy people (5 Male). ISR was determined by mathematical-modeling. Groups were compared with students t-test or ANOVA were appropriate.
Results: Healthy and T2D groups were well matched for age (43±3y vs 46±2 y) and BMI (22±1 vs 22±1 kg/m2), respectively. Glucose area under the curve (AUC) was lower (1179±55 vs 2150±196 mg.ml-1.min, P&lt;0.05) and insulinogenic-index was greater (91±18 vs 23±8, P&lt;0.01) in healthy people than people with T2D, respectively. Rwandans with T2D and normal WC had an ISR-AUC ~2 fold lower (54±9 vs 117±20, P=0.07) than T2D and elevated WC. HOMA-IR was greater in Rwandans with T2D and elevated WC than healthy people (2.2±0.4 vs 0.9±0.1, P&lt;0.05).
Conclusions: In lean Rwandan people with new-onset T2D but normal WC, alterations in insulin secretion rather than insulin-resistance predominate. In contrast, in Rwandans with T2D and elevated WC, insulin resistance rather than insulin secretion may be a major factor. This suggests that the pathogenesis of T2D differs based on WC in Rwandans with implications for prevention and therapy.

Disclosure
R. Mugeni: None. G.I. Smith: None. A.E. Sumner: None. W.T. Cade: None. D. Reeds: None.

Funding
McDonnell FoundationP30DK056341P30DK092950
1570-P: A Human Unique Role of RNA-Binding Protein HuR in Nonalcoholic Steatohepatitis
Authors: TAKAOKA SHOHEI , JASO VERA MARCOS E. , RUAN XIANGBO 
Published: June 2024

Introduction & Objective: Overnutrition-induced obesity heightens the risk of cardiometabolic diseases, necessitating an understanding of how it disrupts gene expression for preventive strategies against obesity-related diseases. The RNA-binding protein human antigen R (HuR) has demonstrated a crucial role in post-transcriptional gene regulation, exhibiting protective effects against nonalcoholic steatohepatitis (NASH) in mouse models. However, the HuR's protective role in human NASH remains uncertain due to potential differences in HuR binding between human and mouse untranslated regions. This study aims to elucidate the role of HuR in human NASH using chimeric mice with humanized livers and cultured human cells.
Methods: Knocking down human HuR was performed in humanized mouse livers, and the impact was assessed by RNA-seq. In human cells, HuR overexpression and co-overexpression with peroxisome proliferator-activated receptor alpha (PPARA) were conducted. Additionally, Western blotting was employed to analyze HuR protein expression in liver samples obtained from healthy donors and NASH patients.
Results: Knocking down human HuR in the humanized liver led to the upregulation of RXRA and fatty acid oxidation-related (FAO) genes. Concurrently, overexpression of HuR in human cells suppressed RXRA protein expression. Furthermore, HuR inhibited PPARA-induced expression of FAO genes by suppressing the PPARA cofactor RXRA. Western blotting analysis revealed elevated HuR and reduced RXRA protein levels in the livers of NASH patients.
Conclusion: This study indicate that HuR is induced in human NASH and suppresses RXRA and FAO genes, suggesting HuR may aggravate NAFLD progression in humans, which is opposite to HuR studies using traditional mouse genetic models.

Disclosure
S. Takaoka: None. M.E. Jaso Vera: None. X. Ruan: None.