17beta-Estradiol modulates apoptosis in pancreatic beta-cells by specific involvement of the sulfonylurea receptor (SUR) isoform SUR1.
Apoptosis of pancreatic beta-cells is an important factor in the pathophysiology of diabetes. Previously, we have shown that the "phytoestrogen" resveratrol can induce beta-cell apoptosis dependent on the expression of sulfonylurea receptor (SUR) 1, the regulatory subunit of pancreatic ATP-sensitive K(+) channels. Here, we investigate whether 17beta-estradiol also influences beta-cell apoptosis in a SUR1-dependent manner. Therefore, islets from wild type or SUR1 knock-out mice, clonal beta-cells, or HEK293 cells expressing different SUR forms were treated with 17beta-estradiol or estrone. Different apoptotic parameters were determined and estrogen binding to SUR was analyzed. In murine islets, 17beta-estradiol treatment resulted in significant apoptotic changes, which in their nature (either apoptotic or anti-apoptotic) were dependent on the age of the animal. These effects were not observed in SUR1 knock-out mice. Furthermore, 17beta-estradiol, which specifically binds to SUR, induced enhanced apoptosis in SUR1-expressing HEK293 cells and clonal beta-cells, whereas apoptosis in recombinant cells expressing SUR2A or SUR2B (cardiac or vascular SUR-isoforms) or sham-transfected control cells was significantly lower. The apoptotic potency of 17beta-estradiol was much higher than that of resveratrol or estrone. SUR1-specific 17beta-estradiol-induced apoptosis was either abolished by the mutation M1289T in transmembrane helix 17 of SUR1 or clearly enhanced by two mutations in nucleotide binding fold 2 (R1379C, R1379L). In conclusion, 17beta-estradiol treatment modulates beta-cell apoptosis under specific involvement of SUR1 in an age-dependent manner. 17beta-Estradiol-induced apoptosis can be influenced by certain SUR1 mutations. These findings may contribute to the understanding of pathophysiological changes in beta-cell mass and could, for instance, provide interesting aspects concerning the etiology of gestational diabetes.
Ackermann
Stefanie
S
Department of Pharmacology and Toxicology, Medical Faculty, University of Tübingen, Wilhelmstrasse 56, D-72074 Tübingen, Germany.
Hiller
Sabrina
S
Osswald
Hartmut
H
Lösle
Martina
M
Grenz
Almut
A
Hambrock
Annette
A
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D016922:Cellular Senescence / Q000187:drug effects / Q000235:genetics; D016640:Diabetes, Gestational / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004958:Estradiol / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology*; D004970:Estrone / Q000494:pharmacology; D005260:Female; D006801:Humans; D050417:Insulin-Secreting Cells / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy; D017510:Protein Folding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D011955:Receptors, Drug / Q000235:genetics / Q000378:metabolism*; D064233:Sulfonylurea Receptors
C577507:ABCC8 protein, human; C577510:ABCC9 protein, human; D018528:ATP-Binding Cassette Transporters; C577508:Abcc8 protein, mouse; C577511:Abcc9 protein, mouse; D004967:Estrogens; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D020033:Protein Isoforms; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D004970:Estrone; D004958:Estradiol