| 1. |
- Granhall, Charlotte, et al.
(författare)
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Separately inherited defects in insulin exocytosis and beta-cell glucose metabolism contribute to type 2 diabetes.
- 2006
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 55:12, s. 3494-3500
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Tidskriftsartikel (refereegranskat)abstract
- The effects of genetic variation on molecular functions predisposing to type 2 diabetes are still largely unknown. Here, in a specifically designed diabetes model, we couple separate gene loci to mechanisms of P-cell pathology. Niddm1i is a major glucose-controlling 16-Mb region in the diabetic GK rat that causes defective insulin secretion and corresponds to loci in humans and mice associated with type 2 diabetes. Generation of a series of congenic rat strains harboring different parts of GK-derived Niddm1i enabled fine mapping of this locus. Congenic strains carrying the GK genotype distally in Niddm1i displayed reduced insulin secretion in response to both glucose and high potassium, as well as decreased single-cell exocytosis. By contrast, a strain carrying the GK genotype proximally in Niddm1i exhibited both intact insulin release in response to high potassium and intact single-cell exocytosis, but insulin secretion was suppressed when stimulated by glucose. Islets from this strain also failed to respond to glucose by increasing the cellular ATP-to-ADP ratio. Changes in P-cell mass did not contribute to the secretory defects. We conclude that the failure of insulin secretion in type 2 diabetes includes distinct functional defects in glucose metabolism and insulin exocytosis of the P-cell and that their genetic fundaments are encoded by different loci within Niddm1i.
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| 2. |
- Taneera, Jalal, et al.
(författare)
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Failure of Transplanted Bone Marrow Cells to Adopt a Pancreatic β-Cell Fate
- 2006
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Ingår i: Diabetes. - Alexandria, USA : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 55:2, s. 290-296
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies in normal mice have suggested that transplanted bone marrow cells can transdifferentiate into pancreatic beta-cells at relatively high efficiency. Herein, adopting the same and alternative approaches to deliver and fate map-transplanted bone marrow cells in the pancreas of normal as well as diabetic mice, we further investigated the potential of bone marrow transplantation as an alternative approach for beta-cell replacement. In contrast to previous studies, transplanted bone marrow cells expressing green fluorescence protein (GFP) under the control of the mouse insulin promoter failed to express GFP in the pancreas of normal as well as diabetic mice. Although bone marrow cells expressing GFP under the ubiquitously expressed beta-actin promoter efficiently engrafted the pancreas of normal and hyperglycemic mice, virtually all expressed CD45 and Mac-1/Gr-1, demonstrating that they adopt a hematopoietic rather than beta-cell fate, a finding further substantiated by the complete absence of GFP(+) cells expressing insulin and the beta-cell transcription factors pancreatic duodenal homeobox factor-1 and homeodomain protein. Thus, transplanted bone marrow cells demonstrated little, if any, capacity to adopt a beta-cell fate.
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