TY - JOUR
T1 - The SNARE protein vti1a functions in dense-core vesicle biogenesis
AU - Walter, Alexander M
AU - Kurps, Julia
AU - de Wit, Heidi
AU - Schöning, Susanne
AU - Toft-Bertelsen, Trine L
AU - Lauks, Juliane
AU - Ziomkiewicz, Iwona
AU - Weiss, Annita N
AU - Schulz, Alexander
AU - Fischer von Mollard, Gabriele
AU - Verhage, Matthijs
AU - Sørensen, Jakob Balslev
N1 - © 2014 The Authors.
PY - 2014/8/1
Y1 - 2014/8/1
N2 - The SNARE protein vti1a is proposed to drive fusion of intracellular organelles, but recent data also implicated vti1a in exocytosis. Here we show that vti1a is absent from mature secretory vesicles in adrenal chromaffin cells, but localizes to a compartment near the trans-Golgi network, partially overlapping with syntaxin-6. Exocytosis is impaired in vti1a null cells, partly due to fewer Ca(2+)-channels at the plasma membrane, partly due to fewer vesicles of reduced size and synaptobrevin-2 content. In contrast, release kinetics and Ca(2+)-sensitivity remain unchanged, indicating that the final fusion reaction leading to transmitter release is unperturbed. Additional deletion of the closest related SNARE, vti1b, does not exacerbate the vti1a phenotype, and vti1b null cells show no secretion defects, indicating that vti1b does not participate in exocytosis. Long-term re-expression of vti1a (days) was necessary for restoration of secretory capacity, whereas strong short-term expression (hours) was ineffective, consistent with vti1a involvement in an upstream step related to vesicle generation, rather than in fusion. We conclude that vti1a functions in vesicle generation and Ca(2+)-channel trafficking, but is dispensable for transmitter release.
AB - The SNARE protein vti1a is proposed to drive fusion of intracellular organelles, but recent data also implicated vti1a in exocytosis. Here we show that vti1a is absent from mature secretory vesicles in adrenal chromaffin cells, but localizes to a compartment near the trans-Golgi network, partially overlapping with syntaxin-6. Exocytosis is impaired in vti1a null cells, partly due to fewer Ca(2+)-channels at the plasma membrane, partly due to fewer vesicles of reduced size and synaptobrevin-2 content. In contrast, release kinetics and Ca(2+)-sensitivity remain unchanged, indicating that the final fusion reaction leading to transmitter release is unperturbed. Additional deletion of the closest related SNARE, vti1b, does not exacerbate the vti1a phenotype, and vti1b null cells show no secretion defects, indicating that vti1b does not participate in exocytosis. Long-term re-expression of vti1a (days) was necessary for restoration of secretory capacity, whereas strong short-term expression (hours) was ineffective, consistent with vti1a involvement in an upstream step related to vesicle generation, rather than in fusion. We conclude that vti1a functions in vesicle generation and Ca(2+)-channel trafficking, but is dispensable for transmitter release.
U2 - 10.15252/embj.201387549
DO - 10.15252/embj.201387549
M3 - Journal article
C2 - 24902738
SN - 0261-4189
VL - 33
SP - 1681
EP - 1697
JO - E M B O Journal
JF - E M B O Journal
ER -