期刊
BRITISH JOURNAL OF PHARMACOLOGY
卷 163, 期 2, 页码 261-271出版社
WILEY
DOI: 10.1111/j.1476-5381.2010.01107.x
关键词
glucagon-like peptide 1; cyclic adenosine monophosphate; adenylate cyclase (AC); phosphodiesterase; guanylin
资金
- Wellcome Trust [WT088357, WT084210]
- Gates Cambridge Trust
- Medical Research Council [G0600717B] Funding Source: researchfish
BACKGROUND AND PURPOSE Glucagon-like peptide-1 (GLP-1) is secreted from enteroendocrine L-cells after food intake. Increasing GLP-1 signalling either through inhibition of the GLP-1 degrading enzyme dipeptidyl-peptidase IV or injection of GLP-1-mimetics has recently been successfully introduced for the treatment of type 2 diabetes. Boosting secretion from the L-cell has so far not been exploited, due to our incomplete understanding of L-cell physiology. Elevation of cyclic adenosine monophosphate (cAMP) has been shown to be a strong stimulus for GLP-1 secretion and here we investigate the activities of adenylate cyclase (AC) and phosphodiesterase (PDE) isozymes likely to shape cAMP responses in L-cells. EXPERIMENTAL APPROACH Expression of AC and PDE isoforms was quantified by RT-PCR. Single cell responses to stimulation or inhibition of AC and PDE isoforms were monitored with real-time cAMP probes. GLP-1 secretion was assessed by elisa. KEY RESULTS Quantitative PCR identified expression of protein kinase C- and Ca2+-activated ACs, corresponding with phorbolester and cytosolic Ca2+-stimulated cAMP elevation. Inhibition of PDE2, 3 and 4 were found to stimulate GLP-1 secretion from murine L-cells in primary culture. This corresponded with cAMP elevations monitored with a plasma membrane targeted cAMP probe. Inhibition of PDE3 but not PDE2 was further shown to prevent GLP-1 secretion in response to guanylin, a peptide secreted into the gut lumen, which had not previously been implicated in L-cell secretion. CONCLUSIONS AND IMPLICATIONS Our results reveal several mechanisms shaping cAMP responses in GLP-1 secreting cells, with some of the molecular components specifically expressed in L-cells when compared with their epithelial neighbours, thus opening new strategies for targeting these cells therapeutically.
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