Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.644734
Title: Mitochondrial involvement in pancreatic beta cell glucolipotoxicity
Author: Barlow, Jonathan
ISNI:       0000 0004 5357 5326
Awarding Body: University of Plymouth
Current Institution: University of Plymouth
Date of Award: 2015
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Abstract:
High circulating glucose and non-esterified free fatty acid (NEFA) levels can cause pancreatic β-cell failure. The molecular mechanisms of this β-cell glucolipotoxicity are yet to be established conclusively. In this thesis by exploring mitochondrial energy metabolism in INS-1E insulinoma cells and isolated pancreatic islets, a role of mitochondria in pancreatic β-cell glucolipotoxicity is uncovered. It is reported that prolonged palmitate exposure at high glucose attenuates glucose-stimulated mitochondrial respiration which is coupled to ADP phosphorylation. These mitochondrial defects coincide with an increased level of mitochondrial reactive oxygen species (ROS), impaired glucose-stimulated insulin secretion (GSIS) and decreased cell viability. Palmitoleate, on the other hand, does not affect mitochondrial ROS levels or cell viability and protects against the adverse effects of palmitate on these phenotypes. Interestingly, palmitoleate does not significantly protect against mitochondrial respiratory or insulin secretion defects and in pancreatic islets tends to limit these functions on its own. Furthermore, strong evidence suggests that glucolipotoxic-induced ROS are of a mitochondrial origin and these ROS are somehow linked with NEFA-induced loss in cell viability. To explore the mechanism of glucolipotxic-induced mitochondrial ROS and associated cell loss, uncoupling protein-2 (UCP2) protein levels and activity were probed in NEFA exposed INS-1E cells. It is concluded that UCP2 neither mediates palmitate-induced mitochondrial ROS production and the related cell loss, nor protects against these deleterious effects. Instead, UCP2 dampens palmitoleate protection against palmitate toxicity. Collectively, these data shed important new light on the area of glucolipotoxicity in pancreatic β-cells and provide novel insights into the pathogenesis of Type 2 diabetes.
Supervisor: Affourtit, Charles Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.644734  DOI: Not available
Keywords: Glucolipotoxicity, Type 2 diabetes, pancreatic beta cells, uncoupling protein 2, reactive oxygen species, mitochondria, bioenergetics
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