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  • Pancreatic β-cell-specific deletion of insulin-degrading enzyme leads to dysregulated insulin secretion and β-cell functional immaturity.

Pancreatic β-cell-specific deletion of insulin-degrading enzyme leads to dysregulated insulin secretion and β-cell functional immaturity.

American journal of physiology. Endocrinology and metabolism (2019-09-04)
Cristina M Fernández-Díaz, Beatriz Merino, José F López-Acosta, Pilar Cidad, Miguel A de la Fuente, Carmen D Lobatón, Alfredo Moreno, Malcolm A Leissring, Germán Perdomo, Irene Cózar-Castellano
ABSTRACT

Inhibition of insulin-degrading enzyme (IDE) has been proposed as a possible therapeutic target for type 2 diabetes treatment. However, many aspects of IDE's role in glucose homeostasis need to be clarified. In light of this, new preclinical models are required to elucidate the specific role of this protease in the main tissues related to insulin handling. To address this, here we generated a novel line of mice with selective deletion of the Ide gene within pancreatic beta-cells, B-IDE-KO mice, which have been characterized in terms of multiple metabolic end points, including blood glucose, plasma C-peptide, and intraperitoneal glucose tolerance tests. In addition, glucose-stimulated insulin secretion was quantified in isolated pancreatic islets and beta-cell differentiation markers and insulin secretion machinery were characterized by RT-PCR. Additionally, IDE was genetically and pharmacologically inhibited in INS-1E cells and rodent and human islets, and insulin secretion was assessed. Our results show that, in vivo, life-long deletion of IDE from beta-cells results in increased plasma C-peptide levels. Corroborating these findings, isolated islets from B-IDE-KO mice showed constitutive insulin secretion, a hallmark of beta-cell functional immaturity. Unexpectedly, we found 60% increase in Glut1 (a high-affinity/low-Km glucose transporter), suggesting increased glucose transport into the beta-cell at low glucose levels, which may be related to constitutive insulin secretion. In parallel, IDE inhibition in INS-1E and islet cells resulted in impaired insulin secretion after glucose challenge. We conclude that IDE is required for glucose-stimulated insulin secretion. When IDE is inhibited, insulin secretion machinery is perturbed, causing either inhibition of insulin release at high glucose concentrations or constitutive secretion.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Anti-GLUT-1 Antibody, CT, from rabbit, purified by affinity chromatography
Sigma-Aldrich
Anti-Glyceraldehyde-3-Phosphate Dehydrogenase Antibody, clone 6C5, clone 6C5, Chemicon®, from mouse
Sigma-Aldrich
Anti-Insulin antibody, Mouse monoclonal, clone K36AC10, purified from hybridoma cell culture