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Exocytosis in insul...
Exocytosis in insulin secreting cells - role of SNARE-proteins
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- Vikman, Jenny (author)
- Lund University,Lunds universitet,Diabetes - öcellsexocytos,Forskargrupper vid Lunds universitet,Diabetes - Islet Cell Exocytosis,Lund University Research Groups
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(creator_code:org_t)
- ISBN 9789185897667
- 2008
- English 114 s.
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Series: Lund University Faculty of Medicine Doctoral Dissertation Series, 1652-8220
- Related links:
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https://lup.lub.lu.s...
Abstract
Subject headings
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- Type 2 diabetes is marked by deterioration in pancreatic β-cell function. SNARE-proteins are crucial for the fusion of insulin granules with the plasma membrane, a prerequisite for insulin secretion. The aim of this thesis has been to investigate the exocytotic process in β-cells with a specific focus on the function and significance of the two SNARE-proteins SNAP-25 and syntaxin 1. SNAP-25 and syntaxin 1 was discovered to be situated in clusters along the plasma membrane. Immunoneutralization of syntaxin 1 and SNAP-25 resulted in a strongly reduced exocytotic response of primed granules in close association with the voltage-dependent calcium channels. Cholesterol is an essential component of the plasma membrane. Desorption of cholesterol from the plasma membrane in β-cells were accompanied with an overall reduction in the response of β-cells, from insulin secretion to exocytosis. We believe this is due to disturbance of a basic mechanism. Indeed, we found that SNAP-25 migrated from the plasma membrane out to the cytosol. The stimulating effect of cAMP on insulin secretion is implemented through different pathways. One pathway is through cAMP-GEFII and its downstream affector RIM2. We show that SNAP-25 binds to both cAMP-GEFII and RIM2, and that this binding mediates the effects of cAMP on exocytosis. The blind-drunk mouse carries a mutation in SNAP-25 that results in increased binding affinities within the SNARE-complex and the consequence in pancreatic β-cells are impaired vesicle recycling and granule exocytosis. These results together demonstrate the significance of a functional exocytotic machinery for β-cells to respond satisfying to an elevation in blood glucose.
Subject headings
- MEDICIN OCH HÄLSOVETENSKAP -- Klinisk medicin -- Endokrinologi och diabetes (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Clinical Medicine -- Endocrinology and Diabetes (hsv//eng)
Keyword
- calcium channel
- cAMP
- syntaxin 1
- SNAP-25
- SNARE
- exocytosis
- Insulin secretion
- pancreatic beta-cells
Publication and Content Type
- dok (subject category)
- vet (subject category)
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