Roles of Sec5 in the Regulation of Dense-Core Vesicle Secretion in PC12 Cells

• Main Author: Jiang, Tiandan T. J.
• Other Authors: Sugita, Shuzo
• Language: en_ca
• Published: 2009
• Subjects: dense-core vesicle; exocytosis; docking; tethering; exocyst; Sec5; 0719
• Online Access: http://hdl.handle.net/1807/25705

The exocyst is thought to tether secretory vesicles to specific sites on the plasma membrane. As a member of the exocyst, Sec5 is implicated in cell survival and membrane growth in Drosophila. Little is known of the exocyst function in mammals, with previous work suggesting involvement of exocyst in GTP-dependent exocytosis. Using RNA interference, we stably down-regulated Sec5 in PC12 cells. We found that these knockdown cells exhibit decreased GTP- and Ca2+-dependent exocytosis of dense-core vesicles (DCVs), and contain less proportion of docked vesicles. Expression of Sec6/8 is also slightly reduced in Sec5 knockdown cells. Our results suggest that Sec5 is involved in both GTP- and Ca2+-dependent exocytosis, possibly through the regulation of DCV docking. We also established doxycycline-inducible knockdown system for Sec5 in PC12 cells which may be more appropriate to study development-related proteins. Efforts were also made to re-introduce Sec5 into the Sec5 knockdown cells for rescue purposes.