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Central role and mechanisms of β-cell dysfunction and death in friedreich ataxia-associated diabetes.
- Source :
-
Annals of neurology [Ann Neurol] 2012 Dec; Vol. 72 (6), pp. 971-82. - Publication Year :
- 2012
-
Abstract
- Objective: Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disease caused in almost all cases by homozygosity for a GAA trinucleotide repeat expansion in the frataxin gene. Frataxin is a mitochondrial protein involved in iron homeostasis. FRDA patients have a high prevalence of diabetes, the pathogenesis of which is not known. We aimed to evaluate the relative contribution of insulin resistance and β-cell failure and the pathogenic mechanisms involved in FRDA diabetes.<br />Methods: Forty-one FRDA patients, 26 heterozygous carriers of a GAA expansion, and 53 controls underwent oral and intravenous glucose tolerance tests. β-Cell proportion was quantified in postmortem pancreas sections from 9 unrelated FRDA patients. Using an in vitro disease model, we studied how frataxin deficiency affects β-cell function and survival.<br />Results: FRDA patients had increased abdominal fat and were insulin resistant. This was not compensated for by increased insulin secretion, resulting in a markedly reduced disposition index, indicative of pancreatic β-cell failure. Loss of glucose tolerance was driven by β-cell dysfunction, which correlated with abdominal fatness. In postmortem pancreas sections, pancreatic islets of FRDA patients had a lower β-cell content. RNA interference-mediated frataxin knockdown impaired glucose-stimulated insulin secretion and induced apoptosis in rat β cells and human islets. Frataxin deficiency sensitized β cells to oleate-induced and endoplasmic reticulum stress-induced apoptosis, which could be prevented by the incretins glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide.<br />Interpretation: Pancreatic β-cell dysfunction is central to diabetes development in FRDA as a result of mitochondrial dysfunction and higher sensitivity to metabolic and endoplasmic reticulum stress-induced β-cell death.<br /> (Copyright © 2012 American Neurological Association.)
- Subjects :
- Adipose Tissue metabolism
Adult
Animals
Body Fat Distribution
Energy Metabolism genetics
Family Health
Female
Flow Cytometry
Friedreich Ataxia genetics
Glucose Tolerance Test
Humans
Hypoglycemic Agents pharmacology
Insulin pharmacology
Insulin Resistance genetics
Insulin-Secreting Cells drug effects
Insulin-Secreting Cells pathology
Linear Models
Male
Middle Aged
Rats
Frataxin
Diabetes Mellitus etiology
Diabetes Mellitus pathology
Friedreich Ataxia complications
Insulin-Secreting Cells physiology
Iron-Binding Proteins genetics
Trinucleotide Repeat Expansion genetics
Subjects
Details
- Language :
- English
- ISSN :
- 1531-8249
- Volume :
- 72
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- Annals of neurology
- Publication Type :
- Academic Journal
- Accession number :
- 23280845
- Full Text :
- https://doi.org/10.1002/ana.23698