The proposed research has two long-range goals: 1) to establish the relationship between the Beta-cell sulfonylurea receptor and the ATP-sensitive K+ channel, and 2) to understand the role of sulfonylurea receptors on non-Beta-cells in the therapy of Type II diabetes. To achieve the first goal, we will make use of a new, potent sulfonylurea, iodo'glyburide', which can be conveniently synthesized in an unlabeled, or 125I-labeled form. We will compare the Kd of receptor binding of this drug to the K0.5 for half- inhibition of K+ efflux, the ED50 for insulin secretion, and the lC50 for inhibition of ATP-sensitive K+ channel activity using hamster insulinoma tumor (HIT) cells. We will determine whether the number of sulfonylurea receptors per cell is equivalent to the number of ATP-sensitive K+ channels and will examine how drugs that are known to alter ATP-sensitive K+ channel activity affect the binding of iodo'glyburide' to its receptor. The molecular weight of the receptor will be established, the protein partially purified, reconstituted into a planar bilayer, and assayed for ATP- sensitive K+ channel activity. We expect these experiments to strengthen the proposal that the ATP-sensitive K+ channel protein contains the sulfonylurea binding site. To prove this, the HIT cell sulfonylurea receptor cDNA will be cloned and expressed, and the expressed protein tested for ATP-sensitive K+ channel activity. Cloning of the receptor cDNA will be by standard protocols. A partial receptor protein sequence will be obtained, oligonucleotides designed based on this sequence, and HIT cell cDNA libraries screened with the oligonucleotides. The putative sulfonylurea receptor encoded by the isolated cDNA will be expressed in Xenopus oocytes, transfected mammalian cells, and E. coli and the protein assayed for 125I-labeled iodo'glyburide' binding and ATP-sensitive K+ channel activity. To begin to understand the role of the sulfonylurea receptor in the therapy of Type II diabetes, we will examine whether non-Beta-cell tissues and cell types also contain this protein, or a similar protein, using as probes the 125I-labeled iodo'glyburide, and the HIT cell receptor cDNA. If the sulfonylurea receptor is also present on peripheral tissue membranes, this would indicate a second role for this protein, possibly related to glucose uptake into these tissues.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
1R01DK041898-01
Application #
3242847
Study Section
Biochemistry Study Section (BIO)
Project Start
1989-07-15
Project End
1994-06-30
Budget Start
1989-07-15
Budget End
1990-06-30
Support Year
1
Fiscal Year
1989
Total Cost
Indirect Cost
Name
Baylor College of Medicine
Department
Type
Schools of Medicine
DUNS #
074615394
City
Houston
State
TX
Country
United States
Zip Code
77030
Nelson, D A; Bryan, J; Wechsler, S et al. (1996) The high-affinity sulfonylurea receptor: distribution, glycosylation, purification, and immunoprecipitation of two forms from endocrine and neuroendocrine cell lines. Biochemistry 35:14793-9
Aguilar-Bryan, L; Nichols, C G; Wechsler, S W et al. (1995) Cloning of the beta cell high-affinity sulfonylurea receptor: a regulator of insulin secretion. Science 268:423-6
Rajan, A S; Luo, Z T; Kahn, B B et al. (1994) Do adipocytes contain high affinity sulfonylurea receptors. Endocrinology 134:1581-8
Boyd 3rd, A E; Moss, L G (1994) The nerve of them--beta-cells and nerve growth factor. Endocrinology 134:2319-20
Rajan, A S; Aguilar-Bryan, L; Nelson, D A et al. (1993) Sulfonylurea receptors and ATP-sensitive K+ channels in clonal pancreatic alpha cells. Evidence for two high affinity sulfonylurea receptors. J Biol Chem 268:15221-8
Nelson, D A; Aguilar-Bryan, L; Bryan, J (1992) Specificity of photolabeling of beta-cell membrane proteins with an 125I-labeled glyburide analog. J Biol Chem 267:14928-33
Aguilar-Bryan, L; Nichols, C G; Rajan, A S et al. (1992) Co-expression of sulfonylurea receptors and KATP channels in hamster insulinoma tumor (HIT) cells. Evidence for direct association of the receptor with the channel. J Biol Chem 267:14934-40
Boyd 3rd, A E; Aguilar-Bryan, L; Bryan, J et al. (1991) Sulfonylurea signal transduction. Recent Prog Horm Res 47:299-316;discussion 316-7
Aguilar-Bryan, L; Nelson, D A; Vu, Q A et al. (1990) Photoaffinity labeling and partial purification of the beta cell sulfonylurea receptor using a novel, biologically active glyburide analog. J Biol Chem 265:8218-24
Boyd 3rd, A E; Aguilar-Bryan, L; Nelson, D A (1990) Molecular mechanisms of action of glyburide on the beta cell. Am J Med 89:3S-10S;discussion 51S-53S

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