Summary
Ligand gated potassium channels, such as the ATP-regulated potassium channel, play crucial roles in coupling of stimuli to insulin secretion in pancreatic beta cells. Mutations in the genes might lead to the insulin secretory defects observed in patients with non-insulin-dependent diabetes mellitus (NIDDM). We isolated a cDNA encoding a putative subunit of a ligand gated potassium channel from a human islet cDNA library. The channel, which we designated hiGIRK2, appeared to be an alternative spliced variant and a human homologue of recently reported mbGIRK2, KATP-2/BIR1. Transcripts were detected in human brain and pancreas, but not in other tissues including cardiac muscle. The sizes of transcripts in the pancreas differed from those in the brain, suggesting tissue-specific alternative splicing and possible isoforms. We then isolated human genomic clones, determined the complete genomic structure and localized the gene to chromosome 21 (21q22). The gene was comprised of four exons and the protein was encoded by three exons. The entire coding region of the hiGIRK2 gene was scanned by polymerase chain reaction-single strand conformation polymorphism analysis in 80 Japanese NIDDM patients. We found five nucleotide substitutions; three were silent mutations of the third base of codons, one in the first intron, 9 bases upstream of exon 2, and one in the 3′-untranslated region. We conclude that mutations in the gene encoding MGIRK2, a (subunit of) ligand gated potassium channel, is not a major determinant of the susceptibility to NIDDM in Japanese.
Similar content being viewed by others
Abbreviations
- NIDDM:
-
Non-insulin-dependent diabetes mellitus
- cDNA:
-
complementary DNA
- PCR:
-
polymerase chain reaction
- SSCP:
-
single strand conformation polymorphism
- K-DR:
-
delayed rectifying (voltage-dependent) potassium channel
- K-ATP:
-
ATP (adenine nucleotide) regulated potassium channel
- K-Ca:
-
Ca2+ activated potassium channel
- K-I:
-
inhibitor activated potassium channel
- ORF:
-
open reading frame
- SUR:
-
sulfonylurea receptor
- ORCC:
-
outward rectifying chloride channel
References
Ashcroft FM, Rorsman P (1989) Electrophysiology of the pancreatic Β-cell. Prog Biophys Molec Biol 54: 87–143
Pongs O (1992) Molecular biology of voltage-dependent potassium channels. Physiol Rev 72:S69-S88
Kubo Y, Baldwin TJ, Jan YN, Jan LY (1993) Primary structure and functional expression of a mouse inward rectifier potassium channel: Nature 362: 127–133
Ho K, Nichols CG, Lederer WJ et al (1993) Cloning and expression of an inwardly rectifying ATP-regulated potassium channel. Nature 362: 31–38
Kubo Y, Reuveny E, Slesinger P, Jan YM, Jan LY (1993) Primary structure and functional expression of a rat G-protein coupled muscarinic potassium channel. Nature 364: 802–806
Ashford MLJ, Bond CT, Blair TA, Adelman JP (1994) Cloning and functional expression of a rat heart KATP channel. Nature 370: 456–459
Krapivinsky G, Gordon EA, Wickman K, Velimirovic B, Krapivinsky L, Clapham DE (1995) The G-protein gated atrial K+ channel IKAch is a heteromultimer of two inwardly rectifying K+-channel proteins. Nature 374: 135–141
Lesage F, Duprat F, Fink M et al. (1994) Cloning provides evidence for a family of inward rectifier and G-protein coupled K+ channels in the brain. FEBS Lett 353: 37–42
Inagaki N, Tsuura Y, Namba N et al. (1995) Cloning and functional characterization of a novel ATP-sensitive potassium channel ubiquitously expressed in rat tissues, including pancreatic islets, pituitary, skeletal muscle, and heart. J Biol Chem 270: 5691–5694
Tsaur M-L, Menzel S, Lai F-P et al. (1995) Isolation of a cDNA clone encoding a KATP channel-like protein expressed in insulin-secreting cells, localization of the human gene to chromosome band 21q22.1, and linkage studies with NIDDM. Diabetes 44: 592–596
Bond CT, ÄmmÄlÄ C, Ashfield R et al. (1995) Cloning and functional expression of the cDNA encoding an inwardly-rectifying potassium channel expressed in pancreatic Β-cells and in the brain. FEBS Lett 367: 61–66
Kosaka K, Hagura R, Kuzuya T (1987) Insulin responses in equivocal and definite diabetes, with special reference to subjects who had mild glucose intolerance but later developed definite diabetes. Diabetes 26: 944–952
Yoneda H, Cha T, Ikegami H et al. (1992) Analysis of early-phase insulin responses in non-obese subjects with mild glucose intolerance. Diabetes Care 15: 1517–1521
Taylor SI, Accili D, Imai Y (1994) Insulin resistance or insulin deficiency. Which is the primary cause of NIDDM? Diabetes 43: 735–740
Sakura H, Bond C, Warren-Perry M et al. (1995) Characterization and variation of a human inwardly-rectifying K-channel gene (KCNJ6): a putative ATP-sensitive K-channel subunit. FEBS Lett 367: 193–197
Zhang Y, Warren-Perry M, Sakura H et al. (1995) No evidence for mutations in a putative Β-cell ATP-sensitive K+ channel subunit in MODY, NIDDM, or GDM. Diabetes 44: 597–600
Yasuda K, Sakura H, Yasumichi M et al. (1995) No evidence for mutations in a putative subunit of the beta-cell ATP-sensitive potassium channel (K-ATP channel) in Japanese NIDDM patients. Biochem Biophys Res Commun 211: 1036–1040
Tanizawa Y, Koranyi LI, Welling CM, Permutt MA (1991) Human liver glucokinase gene: cloning and sequence determination of two alternatively spliced cDNAs. Proc Natl Acad Sci USA 88: 7294–7297
Miyazaki J, Araki K, Yamato E et al. (1990) Establishment of a pancreatic Β cell line that retains glucose-inducible insulin secretion: special reference to expression of glucose transporter isoforms. Endocrinology 127: 126–132
Tanizawa Y, Matsutani A, Chiu KC, Permutt MA (1992) Human glucokinase gene: isolation, structural characterization and identification of a microsatellite repeat polymorphism. Molecular Endocrinol 6: 1070–1081
Kaname T, Miyauchi T, Kuwano A, Matsuda Y, Muramatsu T, Kajii T (1993) Mapping basigin (BSG), a member of the immunoglobulin superfamily, to 19p13.3. Cytogenet Cell Genet 64: 195–197
Kuwano A, Ledbetter SA, Dobyns WB, Emanuel BS, Ledbetter DH (1991) Detection of deletions and cryptic translocation in Miller-Dieker syndrome by in situ hybridization. Am J Hum Genet 49: 707–714
Orita M, Suzuki Y, Sekiya T, Hayashi K (1989) Rapid and sensitive detection of point mutation and DNA polymorphisms using the polymerase chain reaction. Genomics 5: 874–879
Noda K, Matsutani A, Tanizawa Y et al. (1993) Polymorphic microsatellite repeat markers at the glucokinase gene locus are positively associated with non-insulin dependent diabetes mellitus in Japanese. Diabetes 42: 1147–1152
Ferrer J, Nichols CG, Makhina N et al. (1995) Pancreatic islet cells express a family of inwardly rectifying K channel subunits which interact to form G-protein-activated channels. J Biol Chem 270: 26086–26091
Rorsman P, Bokvist K, ÄmmÄlÄ C (1991) Activation by adrenalin of a low-conductance G protein-dependent K+ channel in mouse pancreatic B cells. Nature 349: 77–79
Aguilar-Bryan L, Nichols CG, Wechsler SW et al. (1995) Cloning of the Β cell high-affinity sulfonylurea receptor: a regulator of insulin secretion. Science 268: 423–426
Thomas PM, Cote GJ, Wohllk N et al. (1995) Mutations in the sulfonylurea receptor gene in familial persistent hyperinsulinemic hypoglycaemia of infancy. Science 268: 426–429
Schwiebert EM, Egan ME, Hwan T-H et al. (1995) CFTR regulates outwardly rectifying chloride channels through an autocrine mechanism involving ATP. Cell 81: 1063–1073
Al-Awqati Q (1995) Regulation of ion channels by ABC transporters that secrete ATP. Science 269: 805–806
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Tanizawa, Y., Matsubara, A., Ueda, K. et al. A human pancreatic islet inwardly rectifying potassium channel: cDNA cloning, determination of the genomic structure and genetic variations in Japanese NIDDM patients. Diabetologia 39, 447–452 (1996). https://doi.org/10.1007/BF00400676
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00400676