The broad long-term objective is to obtain new information about the metabolic signals for insulin secretion. The immediate purpose of this project is to gain a better understanding of the role of mitochondrial biosynthetic pathways in insulin secretion. Glucose, the most potent insulin secretagogue, and all other fuel secretagogues stimulate insulin secretion via their metabolism in mitochondria. Our work and that of others has implicated the biosynthesis (anaplerosis) of citric acid cycle intermediates and their export from mitochondria to the cytosol (cataplerosis) in signaling insulin secretion.
Aim 1 is to study the potential products of anaplerosis and will test the hypothesis that the metabolism of all fuel insulin secretagogues shares final common pathways involving mitochondria and that discerning these pathways will yield new clues about mitochondrial factors that couple metabolism and exocytosis. We will follow up a recent surprising discovery from our laboratory that citrate oscillates in beta cell mitochondria supplied with pyruvate and in intact beta cells supplied with glucose, it is hypothesized that citrate can coordinate mitochondrial metabolism with overall cellular metabolism. Studies are planned to determine whether citric acid cycle intermediates besides citrate oscillate in intact ceils, whether non-glucose secretagogues cause oscillations in citric acid cycle intermediates, to learn how mitochondria become synchronized to produce citrate oscillations, and to investigate the regulation of citrate oscillations.
Aim 2 will focus on certain extramitochondrial actions of mitochonddal products to test the hypothesis that most citric acid cycle intermediates have signaling roles in insulin secretion.
In Aim 2 A small interfering RNAs will be used to specifically lower levels of certain enzymes that use mitochondrial products. Resulting decreases in insulin release will be compared with alterations in metabolic pathways.
In Aim 2 B limited focused studies of beta ceil cataplerosis in type 2 diabetes will be performed.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
2R01DK028348-21
Application #
6823104
Study Section
Metabolism Study Section (MET)
Program Officer
Laughlin, Maren R
Project Start
1981-04-01
Project End
2009-05-30
Budget Start
2004-07-07
Budget End
2005-05-30
Support Year
21
Fiscal Year
2004
Total Cost
$480,039
Indirect Cost
Name
University of Wisconsin Madison
Department
Pediatrics
Type
Schools of Medicine
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Ansari, Israr-Ul H; Longacre, Melissa J; Stoker, Scott W et al. (2017) Characterization of Acyl-CoA synthetase isoforms in pancreatic beta cells: Gene silencing shows participation of ACSL3 and ACSL4 in insulin secretion. Arch Biochem Biophys 618:32-43
El Azzouny, Mahmoud; Longacre, Melissa J; Ansari, Israr-Ul H et al. (2016) Knockdown of ATP citrate lyase in pancreatic beta cells does not inhibit insulin secretion or glucose flux and implicates the acetoacetate pathway in insulin secretion. Mol Metab 5:980-987
MacDonald, Michael J; Ade, Lacmbouh; Ntambi, James M et al. (2015) Characterization of phospholipids in insulin secretory granules and mitochondria in pancreatic beta cells and their changes with glucose stimulation. J Biol Chem 290:11075-92
Hasan, Noaman M; Longacre, Melissa J; Stoker, Scott W et al. (2015) Mitochondrial malic enzyme 3 is important for insulin secretion in pancreatic ?-cells. Mol Endocrinol 29:396-410
Ansari, Israr-ul H; Longacre, Melissa J; Paulusma, Coen C et al. (2015) Characterization of P4 ATPase Phospholipid Translocases (Flippases) in Human and Rat Pancreatic Beta Cells: THEIR GENE SILENCING INHIBITS INSULIN SECRETION. J Biol Chem 290:23110-23
Wutthisathapornchai, Apilak; Vongpipatana, Tuangtong; Muangsawat, Sureeporn et al. (2014) Multiple E-boxes in the distal promoter of the rat pyruvate carboxylase gene function as a glucose-responsive element. PLoS One 9:e102730
Madiraju, Anila K; Erion, Derek M; Rahimi, Yasmeen et al. (2014) Metformin suppresses gluconeogenesis by inhibiting mitochondrial glycerophosphate dehydrogenase. Nature 510:542-6
MacDonald, Michael J; Hasan, Noaman M; Dobrzyn, Agnieszka et al. (2013) Knockdown of pyruvate carboxylase or fatty acid synthase lowers numerous lipids and glucose-stimulated insulin release in insulinoma cells. Arch Biochem Biophys 532:23-31
Thonpho, Ansaya; Rojvirat, Pinnara; Jitrapakdee, Sarawut et al. (2013) Characterization of the distal promoter of the human pyruvate carboxylase gene in pancreatic beta cells. PLoS One 8:e55139
MacDonald, M J; Langberg, E-C; Tibell, A et al. (2013) Identification of ATP synthase as a lipid peroxide protein adduct in pancreatic islets from humans with and without type 2 diabetes mellitus. J Clin Endocrinol Metab 98:E727-31

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