Chorein Sensitive Dopamine Release from Pheochromocytoma (PC12) Cells

Chorein, a protein supporting activation of phosphoinositide 3 kinase (PI3K), participates in the regulation of actin polymerization and cell survival. A loss of function mutation of the chorein encoding gene VPS13A (vacuolar protein sorting-associated protein 13A) leads to chorea-acanthocytosis (ChAc), a neurodegenerative disorder with simultaneous erythrocyte akanthocytosis. In blood platelets chorein deficiency has been shown to compromise expression of vesicle-associated membrane protein 8 (VAMP8) and thus degranulation. The present study explored whether chorein is similarly involved in VAMP8 expression and dopamine release of pheochromocytoma (PC12) cells.

Chorein was down-regulated by silencing in PC12 cells. Transmission electron microscopy was employed to quantify the number of vesicles, RT-PCR to determine transcript levels, Western blotting to quantify protein expression and ELISA to determine dopamine release.

Chorein silencing significantly reduced the number of vesicles, VAMP8 transcript levels and VAMP8 protein abundance. Increase of extracellular K+ from 5 mM to 40 mM resulted in marked stimulation of dopamine release, an effect significantly blunted by chorein silencing.

Chorein deficiency down-regulates VAMP8 expression, vesicle numbers and dopamine release in pheochromocytoma cells.