1. Cystic fibrosis-related diabetes is associated with reduced islet protein expression of GLP-1 receptor and perturbation of cell-specific transcriptional programs
- Author
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Sina A. Gharib, Rachna Vemireddy, Joseph J. Castillo, Brendy S. Fountaine, Theo K. Bammler, James W. MacDonald, Rebecca L. Hull-Meichle, and Sakeneh Zraika
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Cystic fibrosis ,Islet ,Glucagon-like peptide 1 ,Glucagon-like peptide 1 receptor ,Insulin ,Glucagon ,Medicine ,Science - Abstract
Abstract Insulin secretion is impaired in individuals with cystic fibrosis (CF), contributing to high rates of CF-related diabetes (CFRD) and substantially increasing disease burden. To develop improved therapies for CFRD, better knowledge of pancreatic pathology in CF is needed. Glucagon like peptide-1 (GLP-1) from islet α cells potentiates insulin secretion by binding GLP-1 receptors (GLP-1Rs) on β cells. We determined whether expression of GLP-1 and/or its signaling components are reduced in CFRD, thereby contributing to impaired insulin secretion. Immunohistochemistry of pancreas from humans with CFRD versus no-CF/no-diabetes revealed no difference in GLP-1 immunoreactivity per islet area, whereas GLP-1R immunoreactivity per islet area or per insulin-positive islet area was reduced in CFRD. Using spatial transcriptomics, we observed several differentially expressed α- and/or β-cell genes between CFRD and control pancreas. In CFRD, we found upregulation of α-cell PCSK1 which encodes the enzyme (PC1/3) that generates GLP-1, and downregulation of α-cell PCSK1N which inhibits PC1/3. Gene set enrichment analysis also revealed α and β cell-specific pathway dysregulation in CFRD. Together, our data suggest intra-islet GLP-1 is not limiting in CFRD, but its action may be restricted due to reduced GLP-1R protein levels. Thus, restoring β-cell GLP-1R protein expression may improve β-cell function in CFRD.
- Published
- 2024
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