1
|
Nicolson TJ, Bellomo EA, Wijesekara N, Loder MK, Baldwin JM, Gyulkhandanyan AV, Koshkin V, Tarasov AI, Carzaniga R, Kronenberger K, Taneja TK, da Silva Xavier G, Libert S, Froguel P, Scharfmann R, Stetsyuk V, Ravassard P, Parker H, Gribble FM, Reimann F, Sladek R, Hughes SJ, Johnson PR, Masseboeuf M, Burcelin R, Baldwin SA, Liu M, Lara-Lemus R, Arvan P, Schuit FC, Wheeler MB, Chimienti F, Rutter GA. Insulin storage and glucose homeostasis in mice null for the granule zinc transporter ZnT8 and studies of the type 2 diabetes-associated variants. Diabetes 2009; 58:2070-83. [PMID: 19542200 PMCID: PMC2731533 DOI: 10.2337/db09-0551] [Citation(s) in RCA: 284] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Accepted: 06/02/2009] [Indexed: 12/03/2022]
Abstract
OBJECTIVE Zinc ions are essential for the formation of hexameric insulin and hormone crystallization. A nonsynonymous single nucleotide polymorphism rs13266634 in the SLC30A8 gene, encoding the secretory granule zinc transporter ZnT8, is associated with type 2 diabetes. We describe the effects of deleting the ZnT8 gene in mice and explore the action of the at-risk allele. RESEARCH DESIGN AND METHODS Slc30a8 null mice were generated and backcrossed at least twice onto a C57BL/6J background. Glucose and insulin tolerance were measured by intraperitoneal injection or euglycemic clamp, respectively. Insulin secretion, electrophysiology, imaging, and the generation of adenoviruses encoding the low- (W325) or elevated- (R325) risk ZnT8 alleles were undertaken using standard protocols. RESULTS ZnT8(-/-) mice displayed age-, sex-, and diet-dependent abnormalities in glucose tolerance, insulin secretion, and body weight. Islets isolated from null mice had reduced granule zinc content and showed age-dependent changes in granule morphology, with markedly fewer dense cores but more rod-like crystals. Glucose-stimulated insulin secretion, granule fusion, and insulin crystal dissolution, assessed by total internal reflection fluorescence microscopy, were unchanged or enhanced in ZnT8(-/-) islets. Insulin processing was normal. Molecular modeling revealed that residue-325 was located at the interface between ZnT8 monomers. Correspondingly, the R325 variant displayed lower apparent Zn(2+) transport activity than W325 ZnT8 by fluorescence-based assay. CONCLUSIONS ZnT8 is required for normal insulin crystallization and insulin release in vivo but not, remarkably, in vitro. Defects in the former processes in carriers of the R allele may increase type 2 diabetes risks.
Collapse
Affiliation(s)
- Tamara J. Nicolson
- Section of Cell Biology, Division of Medicine, Imperial College London, London, U.K
| | - Elisa A. Bellomo
- Section of Cell Biology, Division of Medicine, Imperial College London, London, U.K
| | | | - Merewyn K. Loder
- Section of Cell Biology, Division of Medicine, Imperial College London, London, U.K
| | - Jocelyn M. Baldwin
- Institute of Membrane and Systems Biology, University of Leeds, Leeds, U.K
| | | | - Vasilij Koshkin
- Department of Physiology, University of Toronto, Toronto, Canada
| | - Andrei I. Tarasov
- Section of Cell Biology, Division of Medicine, Imperial College London, London, U.K
| | | | | | - Tarvinder K. Taneja
- Section of Cell Biology, Division of Medicine, Imperial College London, London, U.K
| | | | | | - Philippe Froguel
- Section of Genomic Medicine, Division of Medicine, Imperial College London, London, U.K
- Centre National de la Recherche Scientifique Unite Mixte de Recherche 8090, Institute of Biology, Lille, France
| | | | | | - Philippe Ravassard
- Centre National de la Recherche Scientifique and Université Pierre et Marie Curie, Paris, France
| | - Helen Parker
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, U.K
| | - Fiona M. Gribble
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, U.K
| | - Frank Reimann
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, U.K
| | - Robert Sladek
- Department of Human Genetics, McGill University, Montreal, Canada
| | - Stephen J. Hughes
- Nuffield Department of Surgery, University of Oxford, Oxfordshire, U.K
| | - Paul R.V. Johnson
- Nuffield Department of Surgery, University of Oxford, Oxfordshire, U.K
| | - Myriam Masseboeuf
- Institut de Medecine Moleculaire de Rangueil, INSERM U858, IFR31, Toulouse III University, CHU Rangueil, Toulouse Cedex, Toulouse, France
| | - Remy Burcelin
- Institut de Medecine Moleculaire de Rangueil, INSERM U858, IFR31, Toulouse III University, CHU Rangueil, Toulouse Cedex, Toulouse, France
| | - Stephen A. Baldwin
- Institute of Membrane and Systems Biology, University of Leeds, Leeds, U.K
| | - Ming Liu
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, Michigan
| | - Roberto Lara-Lemus
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, Michigan
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, Michigan
| | - Frans C. Schuit
- Gene Expression Unit, Department of Molecular Cell Biology, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Michael B. Wheeler
- Institute of Membrane and Systems Biology, University of Leeds, Leeds, U.K
| | - Fabrice Chimienti
- Section of Genomic Medicine, Division of Medicine, Imperial College London, London, U.K
| | - Guy A. Rutter
- Section of Cell Biology, Division of Medicine, Imperial College London, London, U.K
| |
Collapse
|
3
|
Itoh S, Gohara S, Inomata R, Matsuyama Y, Yamagishi F. Calcium staining by the glyoxal-bis-(2-hydroxyanil)-method in the livers of rats treated with CCl4, diltiazem, and with both agents together. LIVER 1990; 10:365-71. [PMID: 1706050 DOI: 10.1111/j.1600-0676.1990.tb00482.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We studied the histochemistry of Ca in livers treated with CCl4, diltiazem (one of the Ca antagonists), and both agents together to determine whether hepatocytes or other parts of the liver lesions show Ca staining and whether the grade or location of Ca in these injuries varies. For Ca staining, cryostat sections were treated by the glyoxal-bis-(2-hydroxyanil) (GBHA)-method using O.C.T. imbedding compound instead of paraffin. Diltiazem-treated rats showed Ca granules in the bile canaliculi around the terminal hepatic veins and Kupffer cells 6 h after intragastric injection. Rats treated with CCl4 showed fine red granules in the cytoplasm of the hepatocytes around the terminal hepatic veins as soon as 5 min mildly and 2 h moderately after intraperitoneal injection. Hepatocytes around the terminal hepatic veins showed positive Ca granules 6 to 30 h after intragastric injection of CCl4. Hepatocytes stained by Ca showed acidophilic degeneration and coagulative necrosis. The hepatocytes of rats treated with both diltiazem and CCl4 revealed fewer Ca granules than those treated with CCl4 alone. In summary, Ca was stained by the GBHA method from the early stage of liver injury by CCl4 and was closely involved in acidophilic degeneration and coagulative necrosis of hepatocytes. The Ca staining in liver cells in CCl4-treated rats was decreased by diltiazem.
Collapse
Affiliation(s)
- S Itoh
- Department of Medicine 3, Saitama Medical School, Japan
| | | | | | | | | |
Collapse
|
7
|
Hutton JC, Penn EJ, Peshavaria M. Low-molecular-weight constituents of isolated insulin-secretory granules. Bivalent cations, adenine nucleotides and inorganic phosphate. Biochem J 1983; 210:297-305. [PMID: 6344863 PMCID: PMC1154224 DOI: 10.1042/bj2100297] [Citation(s) in RCA: 171] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The concentrations of Zn2+, Ca2+, Mg2+, Pi and adenine nucleotides were determined in insulin-secretory granules prepared from a transplantable rat insulinoma. Differential and density-gradient centrifugation analyses revealed that Zn2+ in this tissue was principally localized in the secretory granule, a second major fraction being found in association with cytosolic proteins. Pi was principally recovered in the latter fraction, whereas Ca2+ and Mg2+ were more widely distributed. Intragranular ion-distribution experiments suggested that Zn2+ was complexed mainly to insulin and its precursor forms and remained in the granule in an insoluble state. The Zn2+/insulin ratio (0.54) was greater than that expected for insulin molecules having two centrally co-ordinated Zn2+ atoms/hexamer, but less than the maximal Zn2+-binding capacity of the molecule. Most of the granular Ca2+, Mg2+ and Pi was released in a soluble form when granules were disrupted by sonication. Simulation in vitro of the ionic composition of the granule suggested that up to 90% of its Ca2+ was complexed to Pi and adenine nucleotides. Granular macromolecules also bound Ca2+, as shown by equilibrium-dialysis studies of granule lysates. However, such binding was displaced by Mg2+. Examination of the efflux of Ca2+ from granules incubated in iso-osmotic suspensions at 37 degrees C suggested that the passive permeability of the granule membrane to Ca2+ was very low. Nevertheless, more than 50% of the granular Ca2+ was rapidly released in an ionized form on hypo-osmotic or detergent-induced disruption of the granule membrane. This may represent a potentially mobilizable pool of Ca2+ in vivo.
Collapse
|
8
|
Wolters GH, Pasma A, Wiegman JB, Konijnendijk W. Changes in histochemically detectable calcium and zinc during tolbutamide-induced degranulation and subsequent regranulation of rat pancreatic islets. HISTOCHEMISTRY 1983; 78:325-38. [PMID: 6350237 DOI: 10.1007/bf00496620] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Secretory granules of pancreatic B-cells contain high concentrations of zinc and calcium. The effect of gradual degranulation (induced by tolbutamide over a period of 3 days) and the subsequent regranulation (over a period of 4 days) on the histochemically detectable zinc (Zn) and calcium (Ca) content of B-cells was investigated. Zn was stained by dithizone, Ca by glyoxal-bis-(2-hydroxyanil), (GBHA), and B-granules by aldehyde fuchsin (AF). The staining intensities were determined cytophotometrically. A decrease of the granulation by 50% causes a comparable decrease of the Zn content. Almost complete degranulations, however, hardly further diminished the Zn content. Regranulation restores the Zn content parallel to the granulation. The presence of 40% of the initial Zn content in degranulated B-cells suggests the existence of a non-granular Zn fraction. The Zn content of B-cells may be partly involved in the storage of insulin as a Zn-insulin complex in the secretory vesicles. A-cells, however, contain even more (+ 30%) Zn than B-cells. Degranulation of B-cells is accompanied by a moderate decrease of the zinc content of the A-cells. The function of Zn in A-cells is completely unknown. Degranulation of B-cells causes the GBHA-Ca content to decrease to a very low level parallel to the AF-positive granulation. During regranulation the GBHA-Ca content restores parallel to the granulation and reaches after complete regranulation a slightly higher level than in untreated control rats. Almost complete disappearance of CBHA-Ca in the B-cells is accompanied by a decrease of the total islet calcium content of 33%. The results indicate that GBHA stains a Ca fraction which is mainly localized to the secretory granules. The stainability of granular Ca by GBHA is probably based on: a) the high Ca concentration in the granules, b) the presence of ionized Ca in the granules, due to the low intragranular pH, and c) on the properties of GBHA, which stains, under conditions used, only ionized (possibly also readily ionizable) Ca.
Collapse
|