The broad long term objective of this research is to obtain new clues about metabolic signals for insulin secretion. The immediate purpose of this project is to gain an understanding of mitochondrial hydrogen shuttles and their role in metabolizable secretagogue-induced insulin secretion in the pancreatic beta cell. Much of our effort will focus on the mitochondrial glycerol phosphate dehydrogenase (mGPD), the key enzyme in the glycerol phosphate shuttle, to test the hypothesis that mGPD plays an important role in cellular metabolism dehydrogenase (mGPD), the key enzyme in the glycerol phosphate shuttle, to test the hypothesis that mGPD plays an important role in cellular metabolism, including insulin secretion. mGPD is abundant in the normal beta cell, but is reduced in diabetics humans and in rodent models. While a mouse strain (BALB/cHeA) exists that possesses a naturally-occurring null nutation of the cytosolic glycerol phosphate dehydrogenase (the cytosolic half of the shuttle), no mutations or potent inhibitors have been described to eliminate mGPD activity.
The first aim i s to use a recently produced mGPD knockout mouse and the cytosolic null animal to study the role of the glycerol phosphate shuttle and its component enzymes in the whole animals and in isolated islets and mitochondria.
The second aim i s to continue studies of the mGPD promoter to determine factors responsible for high mGPD expression in the beta cell and its decrease in diabetes.
The third aim of this project is to test the hypothesis that there are NADP(H) shuttles in the pancreatic beta cells besides the pyruvate malate shuttle. Much recent evidence suggests that the pyruvate malate shuttle is present in islets. This shuttle utilizes pyruvate carboxylase in the mitochondrial matrix as the enzyme that maintains unidirectionality of the shuttle, and malic enzyme in the cytosol as the NADP(H) oxidoreductase. It is proposed that other shuttles may exist in the beta cell that require the carboxylase, but in combination with other cytosolic with the cytosolic dehydrogenases. Since the levels of both mGPD and pyruvate carboxylase, but in combination with other cytosolic dehydrogenases. Since the levels of both mGPD and pyruvate carboxylase in the beta cell are among the highest in the body, but are decreased in the beta cell in non-insulin dependent diabetes (NIDDM), studies of their regulation will increase the understanding of fuel-stimulated insulin secretion and its defects in NIDDM.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
2R01DK028348-16
Application #
2766052
Study Section
Metabolism Study Section (MET)
Program Officer
Laughlin, Maren R
Project Start
1981-04-01
Project End
2004-03-31
Budget Start
1999-04-01
Budget End
2000-03-31
Support Year
16
Fiscal Year
1999
Total Cost
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
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
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
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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