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Scientific article
English

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

Published inThe Journal of cell biology, vol. 128, no. 6, p. 1019-1028
Publication date1995
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
  • Animals
  • Botulinum Toxins/pharmacology
  • Calcium/pharmacology
  • Cells, Cultured
  • Insulin/ secretion
  • Islets of Langerhans/ metabolism
  • Membrane Proteins
  • Nerve Tissue Proteins/ biosynthesis/drug effects
  • Rats
  • Synaptosomal-Associated Protein 25
Citation (ISO format)
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.
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ISSN of the journal0021-9525
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