Redistribution of F-actin and large dense-cored vesicles in the human neuroblastoma SH-SY5Y in response to secretagogues and protein kinase Cα activation

Our previous studies have shown that noradrenaline release is enhanced by activation of protein kinase C alpha in SH-SY5Y cells. In the present study, we report that activation of protein kinase C alpha leads to (a) partial redistribution of the F-actin cytoskeleton and (b) a 2.5-fold increase in the number of large dense-cored vesicles within 100 nm of the plasma membrane. This redistribution can be prevented by down-regulation of protein kinase C alpha by up to 48 h exposure to phorbol dibutyrate. Treatment with the secretagogues 100 mM KCl, the Ca2+ ionophore A23187 (20 mu M) and 1 mM carbachol also leads to a partial disassembly of the F-actin cytoskeleton. This is accompanied by an increase in the number of large dense cored vesicles at the: plasma membrane following exposure to KCl and A23187 but not following exposure to carbachol. These results are discussed in relation to the hypothesis that a key step in the enhancement of noradrenaline release following activation of protein kinase C alpha and elevation of intracellular calcium is the movement of large dense cored vesicles to the plasma membrane following partial disassembly of the F-actin cytoskeleton. (C) 1999 Elsevier Science B.V. All rights reserved.