Cleavage of SNAP-25 and VAMP-2 impairs store-operated Ca2+ entry in mouse pancreatic acinar cells.
We recently reported that store-operated Ca(2+) entry (SOCE) in nonexcitable cells is likely to be mediated by a reversible interaction between Ca(2+) channels in the plasma membrane and the endoplasmic reticulum, a mechanism known as "secretion-like coupling." As for secretion, in this model the actin cytoskeleton plays a key regulatory role. In the present study we have explored the involvement of the secretory proteins synaptosome-associated protein (SNAP-25) and vesicle-associated membrane protein (VAMP) in SOCE in pancreatic acinar cells. Cleavage of SNAP-25 and VAMPs by treatment with botulinum toxin A (BoNT A) and tetanus toxin (TeTx), respectively, effectively inhibited amylase secretion stimulated by the physiological agonist CCK-8. BoNT A significantly reduced Ca(2+) entry induced by store depletion using thapsigargin or CCK-8. In addition, treatment with BoNT A once SOCE had been activated reduced Ca(2+) influx, indicating that SNAP-25 is needed for both the activation and maintenance of SOCE in pancreatic acinar cells. VAMP-2 and VAMP-3 are expressed in mouse pancreatic acinar cells. Both proteins associate with the cytoskeleton upon Ca(2+) store depletion, although only VAMP-2 seems to be sensitive to TeTx. Treatment of pancreatic acinar cells with TeTx reduced the activation of SOCE without affecting its maintenance. These findings support a role for SNAP-25 and VAMP-2 in the activation of SOCE in pancreatic acinar cells and show parallels between this process and secretion in a specialized secretory cell type.
Rosado
Juan A
JA
Department of Physiology, University of Extremadura, Cáceres, Spain. jarosado@unex.es <jarosado@unex.es>
Redondo
Pedro C
PC
Salido
Ginés M
GM
Sage
Stewart O
SO
Pariente
Jose A
JA
D000681:Amylases / Q000378:metabolism; D000818:Animals; D019274:Botulinum Toxins, Type A / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005765:Gastrointestinal Agents / Q000494:pharmacology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D046790:Pancreas, Exocrine / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D050683:R-SNARE Proteins; D012844:Sincalide / Q000494:pharmacology; D050825:Synaptosomal-Associated Protein 25; D013744:Tetanus Toxin / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
D004791:Enzyme Inhibitors; D005765:Gastrointestinal Agents; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050683:R-SNARE Proteins; C494209:Snap25 protein, mouse; D050825:Synaptosomal-Associated Protein 25; D013744:Tetanus Toxin; D019284:Thapsigargin; D000681:Amylases; D019274:Botulinum Toxins, Type A; D012844:Sincalide; D002118:Calcium