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SNAP-25 is expressed in islets of Langerhans and is involved in insulin release

Montecucco, C.
Weller, U.
Catsicas, S.
Published in The journal of cell biology. 1995, vol. 128, no. 6, p. 1019-1028
Abstract SNAP-25 is known as a neuron specific molecule involved in the fusion of small synaptic vesicles with the presynaptic plasma membrane. By immunolocalization and Western blot analysis, it is now shown that SNAP-25 is also expressed in pancreatic endocrine cells. Botulinum neurotoxins (BoNT) A and E were used to study the role of SNAP-25 in insulin secretion. These neurotoxins inhibit transmitter release by cleaving SNAP-25 in neurons. Cells from a pancreatic B cell line (HIT) and primary rat islet cells were permeabilized with streptolysin-O to allow toxin entry. SNAP-25 was cleaved by BoNT/A and BoNT/E, resulting in a molecular mass shift of approximately 1 and 3 kD, respectively. Cleavage was accompanied by an inhibition of Ca(++)-stimulated insulin release in both cell types. In HIT cells, a concentration of 30-40 nM BoNT/E gave maximal inhibition of stimulated insulin secretion of approximately 60%, coinciding with essentially complete cleavage of SNAP-25. Half maximal effects in terms of cleavage and inhibition of insulin release were obtained at a concentration of 5-10 nM. The A type toxin showed maximal and half-maximal effects at concentrations of 4 and 2 nM, respectively. In conclusion, the results suggest a role for SNAP-25 in fusion of dense core secretory granules with the plasma membrane in an endocrine cell type- the pancreatic B cell.
Keywords AnimalsBotulinum Toxins/pharmacologyCalcium/pharmacologyCells, CulturedInsulin/ secretionIslets of Langerhans/ metabolismMembrane ProteinsNerve Tissue Proteins/ biosynthesis/drug effectsRatsSynaptosomal-Associated Protein 25
PMID: 7896868
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SADOUL, Karin et al. SNAP-25 is expressed in islets of Langerhans and is involved in insulin release. In: The Journal of Cell Biology, 1995, vol. 128, n° 6, p. 1019-1028. https://archive-ouverte.unige.ch/unige:9009

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Deposited on : 2010-07-12

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