title: Mouse insulin cells expressing an inducible RIPCre transgene are functionally impaired.
abstract: We used cre-lox technology to test whether the inducible expression of Cre minimize the deleterious effect of the enzyme on beta cell function. We studied mice in which Cre is linked to a modified estrogen receptor (ER), and its expression is controlled by the rat insulin promoter (RIP). Following the injection of tamoxifen (TM), CreER- migrates to the nucleus and promotes the appearance of a reporter protein, enhanced yellow fluorescent protein (EYFP), in cells. Immunocytochemical analysis indicated that 46.6 ± 2.1% insulin cells of adult RIPCreER- EYFP expressed EYFP. RIPCreER-EYFP (+TM) mice were normoglycemic throughout the study, and their glucose tolerance test results were similar to control CD-1 mice. However, an extended exposure to reagents that stimulate insulin synthesis was detrimental to the survival of IN+EYFP+cells. The administration of an inhibitor of the enzyme dipeptidyl-peptidase (DPP4i), which prevents the cleavage of glucagon-like peptide (GLP-1), to adult RIPCreER-EYFP mice lead to a decrease in the percentage of IN+EYFP+ to 17.5 ± 1.73 and a significant increase in apoptotic cells in islets. Similarly, a 2-week administration of the GLP-1 analog exendin 4 (ex-4) induced an almost complete ablation of IN+ expressing a different reporter protein and a significant decrease in the beta cell mass and rate of beta cell proliferation. Since normal beta cells do not die when induced to increase insulin synthesis, our observations indicate that insulin cells expressing an inducible RIPCre transgene are functionally deficient. Studies employing these mice should carefully consider the pitfalls of the Cre-Lox technique.
authors.affiliation: From the Department of Cell Biology, SUNY-Downstate Medical Center, Brooklyn, New York 11203 gteitelman@downstate.edu.
authors.forename: Gladys
authors.initials: G
authors.lastname: Teitelman
authors.affiliation: From the Department of Cell Biology, SUNY-Downstate Medical Center, Brooklyn, New York 11203.
authors.forename: Mamdouh
authors.initials: M
authors.lastname: Kedees
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism; D000077270:Exenatide; D017930:Genes, Reporter; D000067757:Glucagon-Like Peptide-1 Receptor; D018149:Glucose Intolerance / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000235:genetics* / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D019426:Integrases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D010455:Peptides / Q000494:pharmacology; D010641:Phenotype; D011401:Promoter Regions, Genetic; D011480:Protease Inhibitors / Q000494:pharmacology; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D018027:Receptors, Glucagon / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology; D013629:Tamoxifen / Q000494:pharmacology; D014688:Venoms / Q000494:pharmacology
chemical_list: C000593834:Glp1r protein, mouse; C000593835:Glp1r protein, rat; D000067757:Glucagon-Like Peptide-1 Receptor; D007004:Hypoglycemic Agents; D007328:Insulin; D010455:Peptides; D011480:Protease Inhibitors; D011960:Receptors, Estrogen; D018027:Receptors, Glucagon; D011994:Recombinant Proteins; D020845:Selective Estrogen Receptor Modulators; D014688:Venoms; D013629:Tamoxifen; D049452:Green Fluorescent Proteins; D000077270:Exenatide; C045073:Cre recombinase; D019426:Integrases; D018819:Dipeptidyl Peptidase 4; C545245:Dpp4 protein, mouse
keywords: Apoptosis; Beta Cells; Gene Knockout; Insulin Synthesis; Pancreatic Islet; Transgenic Mice