Biochemical Mechanisms Controlling Bioreactivity of Adrenal Chromaffin Cells

Abstract : This project investigated the cellular, molecular and biochemical mechanisms that control the response of the rat adrenal gland to physiological stimulation. We found that the responsivity of this tissue will change following specific treatments including chronic treatment of rats with insulin and acute depolarization of the cells with KCl. The alternation in adrenal reactivity appears to be directly correlated with the cellular concentrations of catecholamine neurotransmitters. This past year has been spent investigating the biochemical mechanisms that may be responsible for this change in bioreactivity. Since the most important biochemical mechanism controlling cellular function is protein phosphorylation, we focussed on this method of control. We have identified a novel protein kinase activity that phosphorylates both tyrosine hydroxylase and synapsin at a unique site. Most recent research has involved the phosphorylation of other structural proteins by this proline-directed protein kinase. In addition, we have examined the role protein kinase C in regulating the response of PCI2 cells to a variety of growth factors in culture.