Reduced PDX-1 expression impairs islet response to insulin resistance and worsens glucose homeostasis
Open Access
- 1 April 2005
- journal article
- Published by American Physiological Society in American Journal of Physiology-Endocrinology and Metabolism
- Vol. 288 (4), E707-E714
- https://doi.org/10.1152/ajpendo.00252.2004
Abstract
In type 2 diabetes mellitus, insulin resistance and an inadequate pancreatic β-cell response to the demands of insulin resistance lead to impaired insulin secretion and hyperglycemia. Pancreatic duodenal homeodomain-1 (PDX-1), a transcription factor required for normal pancreatic development, also plays a key role in normal insulin secretion by islets. To investigate the role of PDX-1 in islet compensation for insulin resistance, we examined glucose disposal, insulin secretion, and islet cell mass in mice of four different genotypes: wild-type mice, mice with one PDX-1 allele inactivated (PDX-1+/−, resulting in impaired insulin secretion), mice with one GLUT4 allele inactivated (GLUT4+/−, resulting in insulin resistance), and mice heterozygous for both PDX-1 and GLUT4 (GLUT4+/−;PDX-1+/−). The combination of PDX-1 and GLUT4 heterozygosity markedly prolonged glucose clearance. GLUT4+/−;PDX-1+/−mice developed β-cell hyperplasia but failed to increase their β-cell insulin content. These results indicate that PDX-1 heterozygosity (∼60% of normal protein levels) abrogates the β-cell's compensatory response to insulin resistance, impairs glucose homeostasis, and may contribute to the pathogenesis of type 2 diabetes.Keywords
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