Expression and localization of cystic fibrosis transmembrane conductance regulator in the rat endocrine pancreas
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Impaired glucose tolerance and overt diabetes mellitus are becoming increasingly common complications of cystic fibrosis (CF), most probably merely as a result of increased life expectancy. In order to understand the pathophysiology of cystic fibrosis-related diabetes (CFRD), knowledge on the possible expression and cell distribution of the cystic fibrosis transmembrane conductance regulator (CFTR) protein within the endocrine pancreas is required. In this report, we establish the first evidence for expression of CFTR protein in rat pancreatic islets by using independent techniques. First reverse transcriptase-polymerase chain reaction (RT-PCR) amplification showed that CFTR mRNA is present in isolated islets of Langerhans. Furthermore, the analysis of flow cytometry-separated islet cells indicated that the level of CFTR transcripts is significantly higher in the non-β than in β-cell populations. The expression of CFTR protein in rat islet cells was also demonstrated by Western blotting and the level of expression was also found significantly higher in the non-β than in β-cell populations. Last, in situ immunocytochemistry studies with two monoclonal antibodies recognizing different CFTR epitopes indicated that CFTR expression occurs mainly in glucagon-secreting α-cells.
KeywordsCystic fibrosis CFTR Islets of Langerhans Alpha and beta cells Cystic Fibrosis Related Diabetes (CFRD) Glucagon
We thank Jacqueline Van Geffel for assistance in the RT-PCR and Prof. Alex Bollen for helpful discussion. We also thank Prof. H.-C. Fehmann (from Philipps-University of Marburg, Marburg, Germany) for providing INR1-G9 alpha cell line and Dr A. Pavirani from Transgène (Strasbourg, France) for providing the MATG 1104 antibody used in this study. This work was supported by the “Fonds Alphonse et Jean Forton”, the “Fondation Jean Brachet” and the “Fonds de la Recherche Scientifique Médicale” (FRSM).
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