Browsing by Subject "Glucose homeostasis"
Item 4033 Evaluating the Effect of Prebiotics on the Gut Microbiome Profile and Beta-cell Function in Newly-Diagnosed Type 1 Diabetes(Cambridge University Press, 2020-07-29) Ismail, Heba M.; Evans-Molina, Carmella; DiMeglio, Linda; Pediatrics, School of MedicineOBJECTIVES/GOALS: Type 1 diabetes (T1D) results from the autoimmune destruction of insulin-producing β-cells. Emerging data suggest that differences in intestinal microbiota might be critically involved both in autoimmunity and in glucose homeostasis. The prebiotic high amylose maize starch (HAMS) alters the gut microbiome profile and metabolites positively by increasing production of beneficial short chain fatty acids (SCFAs) that have significant anti-inflammatory effects. HAMS also improves glycemia, insulin sensitivity and secretion in healthy non-diabetic adults. Further, an acetylated and butyrylated form of HAMS (HAMS-AB) that increases beneficial SCFA production, namely acetate and butyrate, has been safe and effective in disease prevention in mouse T1D models. The objective of the proposed study is to assess the effect of administering a prebiotic, such as HAMS-AB, on the gut microbiome profile, SCFA production, glycemia and β-cell function in humans with T1D. METHODS/STUDY POPULATION: We hypothesize that administration of HAMS-AB will (i) improve the gut microbiome profile in humans with T1D, (ii) increase SCFA production, and (iii) improve β-cell health, β-cell function and overall glycemia. We propose a pilot randomized controlled cross-over trial of HAMS-AB in 12 youth with newly-diagnosed T1D. We will use state-of-the-art markers to profile the gut microbiome (using 16S rRNA sequencing), measure stool SCFA levels (using gas chromatography), asses β-cell stress/death (by measuring proinsulin to C-peptide ratios) and glycemia (assessed by continuous glucose monitoring and HbA1c measurements). RESULTS/ANTICIPATED RESULTS: We expect that the use of HAMS-AB in newly diagnosed youth with type 1 diabetes will alter the gut microbiome profile (thus increasing the number of fermenters and SCFA levels), β-cell function and glycemia in humans with T1D. DISCUSSION/SIGNIFICANCE OF IMPACT: Given the unknown long-term effects of immune-modulatory therapy on those at risk for or those diagnosed with T1D, the use of a prebiotic such as HAMS-AB offers a simple, safe, yet inexpensive and tolerated dietary alternative approach to mitigating disease.Item DOC2B promotes insulin sensitivity in mice via a novel KLC1-dependent mechanism in skeletal muscle(Springer Verlag, 2019-05) Zhang, Jing; Oh, Eunjin; Merz, Karla E.; Aslamy, Arianne; Veluthakal, Rajakrishnan; Salunkhe, Vishal A.; Ahn, Miwon; Tunduguru, Ragadeepthi; Thurmond, Debbie C.; Cellular and Integrative Physiology, School of MedicineAims/hypothesis: Skeletal muscle accounts for >80% of insulin-stimulated glucose uptake; dysfunction of this process underlies insulin resistance and type 2 diabetes. Insulin sensitivity is impaired in mice deficient in the double C2 domain β (DOC2B) protein, while whole-body overexpression of DOC2B enhances insulin sensitivity. Whether insulin sensitivity in the skeletal muscle is affected directly by DOC2B or is secondary to an effect on other tissues is unknown; the underlying molecular mechanisms also remain unclear. Methods: Human skeletal muscle samples from non-diabetic or type 2 diabetic donors were evaluated for loss of DOC2B during diabetes development. For in vivo analysis, new doxycycline-inducible skeletal-muscle-specific Doc2b-overexpressing mice fed standard or high-fat diets were evaluated for insulin and glucose tolerance, and insulin-stimulated GLUT4 accumulation at the plasma membrane (PM). For in vitro analyses, a DOC2B-overexpressing L6-GLUT4-myc myoblast/myotube culture system was coupled with an insulin resistance paradigm. Biochemical and molecular biology methods such as site-directed mutagenesis, co-immunoprecipitation and mass spectrometry were used to identify the molecular mechanisms linking insulin stimulation to DOC2B. Results: We identified loss of DOC2B (55% reduction in RNA and 40% reduction in protein) in the skeletal muscle of human donors with type 2 diabetes. Furthermore, inducible enrichment of DOC2B in skeletal muscle of transgenic mice enhanced whole-body glucose tolerance (AUC decreased by 25% for female mice) and peripheral insulin sensitivity (area over the curve increased by 20% and 26% for female and male mice, respectively) in vivo, underpinned by enhanced insulin-stimulated GLUT4 accumulation at the PM. Moreover, DOC2B enrichment in skeletal muscle protected mice from high-fat-diet-induced peripheral insulin resistance, despite the persistence of obesity. In L6-GLUT4-myc myoblasts, DOC2B enrichment was sufficient to preserve normal insulin-stimulated GLUT4 accumulation at the PM in cells exposed to diabetogenic stimuli. We further identified that DOC2B is phosphorylated on insulin stimulation, enhancing its interaction with a microtubule motor protein, kinesin light chain 1 (KLC1). Mutation of Y301 in DOC2B blocked the insulin-stimulated phosphorylation of DOC2B and interaction with KLC1, and it blunted the ability of DOC2B to enhance insulin-stimulated GLUT4 accumulation at the PM. Conclusions/interpretation: These results suggest that DOC2B collaborates with KLC1 to regulate insulin-stimulated GLUT4 accumulation at the PM and regulates insulin sensitivity. Our observation provides a basis for pursuing DOC2B as a novel drug target in the muscle to prevent/treat type 2 diabetes.Item Early high plasma ST2, the decoy IL-33 receptor, in children undergoing hematopoietic cell transplantation is associated with the development of post-transplant diabetes mellitus(Ferrata Storti Foundation, 2020-05) Rowan, Courtney M.; Teagarden, Alicia M.; Cater, Daniel T.; Moser, Elizabeth A.S.; Baykoyanni, Giorgos; Paczesny, Sophie; Pediatrics, School of MedicineItem Exocytosis proteins as novel targets for diabetes prevention and/or remediation?(American Physiological Society, 2017-05-01) Aslamy, Arianne; Thurmond, Debbie C.; Cellular and Integrative Physiology, School of MedicineDiabetes remains one of the leading causes of morbidity and mortality worldwide, affecting an estimated 422 million adults. In the US, it is predicted that one in every three children born as of 2000 will suffer from diabetes in their lifetime. Type 2 diabetes results from combinatorial defects in pancreatic β-cell glucose-stimulated insulin secretion and in peripheral glucose uptake. Both processes, insulin secretion and glucose uptake, are mediated by exocytosis proteins, SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complexes, Sec1/Munc18 (SM), and double C2-domain protein B (DOC2B). Increasing evidence links deficiencies in these exocytosis proteins to diabetes in rodents and humans. Given this, emerging studies aimed at restoring and/or enhancing cellular levels of certain exocytosis proteins point to promising outcomes in maintaining functional β-cell mass and enhancing insulin sensitivity. In doing so, new evidence also shows that enhancing exocytosis protein levels may promote health span and longevity and may also harbor anti-cancer and anti-Alzheimer's disease capabilities. Herein, we present a comprehensive review of the described capabilities of certain exocytosis proteins and how these might be targeted for improving metabolic dysregulation.Item FOXO transcription factors protect against the diet-induced fatty liver disease(SpringerNature, 2017-03-16) Pan, Xiaoyan; Zhang, Yang; Kim, Hyeong-Geug; Liangpunsakul, Suthat; Dong, X. Charlie; Department of Biochemistry & Molecular Biology, IU School of MedicineForkhead O transcription factors (FOXOs) have been implicated in glucose and lipid homeostasis; however, the role of FOXOs in the development of nonalcoholic fatty liver disease (NAFLD) is not well understood. In this study, we designed experiments to examine the effects of two different diets-very high fat diet (HFD) and moderately high fat plus cholesterol diet (HFC)-on wildtype (WT) and liver-specific Foxo1/3/4 triple knockout mice (LTKO). Both diets induced severe hepatic steatosis in the LTKO mice as compared to WT controls. However, the HFC diet led to more severe liver injury and fibrosis compared to the HFD diet. At the molecular levels, hepatic Foxo1/3/4 deficiency triggered a significant increase in the expression of inflammatory and fibrotic genes including Emr1, Ccl2, Col1a1, Tgfb, Pdgfrb, and Timp1. Thus, our data suggest that FOXO transcription factors play a salutary role in the protection against the diet-induced fatty liver disease.Item The Role of Mediobasal Hypothalamic PACAP in the Control of Body Weight and Metabolism(Oxford University Press, 2021) Bozadjieva-Kramer, Nadejda; Ross, Rachel A.; Johnson, David Q.; Fenselau, Henning; Haggerty, David L.; Atwood, Brady; Lowell, Bradford; Flak, Jonathan N.; Pharmacology and Toxicology, School of MedicineBody energy homeostasis results from balancing energy intake and energy expenditure. Central nervous system administration of pituitary adenylate cyclase activating polypeptide (PACAP) dramatically alters metabolic function, but the physiologic mechanism of this neuropeptide remains poorly defined. PACAP is expressed in the mediobasal hypothalamus (MBH), a brain area essential for energy balance. Ventromedial hypothalamic nucleus (VMN) neurons contain, by far, the largest and most dense population of PACAP in the medial hypothalamus. This region is involved in coordinating the sympathetic nervous system in response to metabolic cues in order to re-establish energy homeostasis. Additionally, the metabolic cue of leptin signaling in the VMN regulates PACAP expression. We hypothesized that PACAP may play a role in the various effector systems of energy homeostasis, and tested its role by using VMN-directed, but MBH encompassing, adeno-associated virus (AAVCre) injections to ablate Adcyap1 (gene coding for PACAP) in mice (Adcyap1MBHKO mice). Adcyap1MBHKO mice rapidly gained body weight and adiposity, becoming hyperinsulinemic and hyperglycemic. Adcyap1MBHKO mice exhibited decreased oxygen consumption (VO2), without changes in activity. These effects appear to be due at least in part to brown adipose tissue (BAT) dysfunction, and we show that PACAP-expressing cells in the MBH can stimulate BAT thermogenesis. While we observed disruption of glucose clearance during hyperinsulinemic/euglycemic clamp studies in obese Adcyap1MBHKO mice, these parameters were normal prior to the onset of obesity. Thus, MBH PACAP plays important roles in the regulation of metabolic rate and energy balance through multiple effector systems on multiple time scales, which highlight the diverse set of functions for PACAP in overall energy homeostasis.Item SAT074 Induction Of Insulin Hypersecretion Uncovers Distinctions Between Adaptive And Maladaptive Endoplasmic Reticulum Stress Response In Beta Cells(The Endocrine Society, 2023-10-05) Roy, Gitanjali; Rodrigues dos Santos, Karina; Kwakye, Michael B.; Tan, Zhiyong; Johnson, Travis S.; Kalwat, Michael A.; Biostatistics and Health Data Science, School of MedicinePancreatic islet β-cells release insulin to maintain glucose homeostasis. β-cells must translate, package, and secrete large amounts of insulin. During this process the unfolded protein response of the endoplasmic reticulum (UPRER) is induced to maintain these functions. However, stimuli that force β-cell to secrete insulin at enhanced rates and for prolonged durations risk inducing the terminal UPRER and eventual apoptosis. In a chemical screen for insulin secretion modulators, we discovered SW016789 which caused hypersecretion of insulin and led to a transient induction of the UPRER, but not apoptosis. In contrast, SERCA2 ER Ca2+ pump inhibitor thapsigargin induces the terminal UPRER. We hypothesized that SW016789 can be used as a tool compound to discover genes involved in β-cell adaptation to hypersecretion-induced stress. We performed time course transcriptomics in MIN6 β-cells exposed to SW016789 (5 µM) or thapsigargin (100 nM) from 0-24 h. Unbiased analyses using a Dirichlet process Gaussian process (DPGP) method revealed clusters of genes temporally co-regulated and the genes within these clusters were distinct between SW016789 and thapsigargin treatments. In particular, after 6 h of SW016789-induced hypersecretion we found a highly induced cluster of genes (SW cluster 3) enriched in adaptive UPRER factors (e.g. Manf). Conversely, most of the thapsigargin-induced genes clustered at 24 h and were enriched for terminal UPRER factors (e.g. Txnip). Pathway analysis of SW cluster 3 indicated that genes involved in in regulation of mRNA methylation and ER-associated degradation were also induced by SW016789 sooner and with greater amplitude than by thapsigargin, suggesting distinct differences in the handling of protein translation and degradation. From the SW cluster 3 genes we selected proteins known to be ER-associated or secreted and generated stable transgenic or CRISPR knockout MIN6 β-cell lines for each. Our data suggest altered expression of these factors may impair glucose-stimulated insulin secretion responses and alter cell viability in presence or absence of ER stressors including cytokines, thapsigargin, and tunicamycin. In conclusion, we have successfully shown that pharmacological induction of insulin hypersecretion can induce a distinct transcriptional outcome from that of canonically-induced UPRER and that we can take advantage of this property to discover new β-cell regulatory pathways and targets. We envision this dataset as a resource for the secretory biology and islet biology communities.Item Tequila Regulates Insulin-Like Signaling and Extends Life Span in Drosophila melanogaster(Oxford University Press, 2015-12) Huang, Cheng-Wen; Wang, Horng-Dar; Bai, Hua; Wu, Ming-Shiang; Yen, Jui-Hung; Tatar, Marc; Fu, Tsai-Feng; Wang, Pei-Yu; Department of Microbiology and Immunology, IU School of MedicineThe aging process is a universal phenomenon shared by all living organisms. The identification of longevity genes is important in that the study of these genes is likely to yield significant insights into human senescence. In this study, we have identified Tequila as a novel candidate gene involved in the regulation of longevity in Drosophila melanogaster. We have found that a hypomorphic mutation of Tequila (Teq(f01792)), as well as cell-specific downregulation of Tequila in insulin-producing neurons of the fly, significantly extends life span. Tequila deficiency-induced life-span extension is likely to be associated with reduced insulin-like signaling, because Tequila mutant flies display several common phenotypes of insulin dysregulation, including reduced circulating Drosophila insulin-like peptide 2 (Dilp2), reduced Akt phosphorylation, reduced body size, and altered glucose homeostasis. These observations suggest that Tequila may confer life-span extension by acting as a modulator of Drosophila insulin-like signaling.