Protein kinase C-ε plays a role in neurite outgrowth in response to epidermal growth factor and nerve growth factor in PC12 cells

In this study, we examined the role of specific protein kinase C (PKc) isoforms in the differentiation of PC12 cells in response to nerve growth factor (NGF) and epidermal growth factor (EGF). PC12 cells express PKC-α, - β, -γ -δ, -ε, -μ, and -ζ. For PKC-δ, -ε, and -ζ, NGF and EGF exerted differential effects on translocation. Unlike overexpression of PKC-α and - δ, overexpression of PKC-ε caused enhanced neurite outgrowth in response to NGF. In the PKC-ε-overexpressing cells, EGF also dramatically induced neurite outgrowth, arrested cell proliferation, and induced a sustained phosphorylation of mitogen-activated protein kinase (MAPK), in contrast to its mitogenic effects on control cells or cells overexpressing PKC-α and - δ. The induction of neurite outgrowth by EGF was inhibited by the MAPK kinase inhibitor PD95098. In cells overexpressing a PKC-ε dominant negative mutant, NGF induced reduced neurite outgrowth and a more transient phosphorylation of MAPK than in controls. Our results suggest an important role for PKC-ε in neurite outgrowth in PC12 cells, probably via activation of the MAPK pathway.