A novel PIP2 binding of εpKC and its contribution to the neurite induction ability

Abstract

Protein kinase C-ε (εPKC) induces neurite outgrowth in neuroblastoma cells but molecular mechanism of the εPKC-induced neurite outgrowth is not fully understood. Therefore, we investigated the ability of phosphatidylinositol 4,5-bisphosphate (PIP2) binding of εPKC and its correlation with the neurite extension. We found that full length εPKC bound to PIP2 in a 12-o-tetradecanoylphorbol-13-acetate dependent manner, while the regulatory domain of εPKC (εRD) bound to PIP 2 without any stimulation. To identify the PIP2 binding region, we made mutants lacking several regions from εRD, and examined their PIP2 binding activity. The mutants lacking variable region 1 (V1) bound to PIP2 stronger than intact εRD, while the mutants lacking pseudo-substrate or common region 1 (C1) lost the binding. The PIP 2 binding ability of the V3-deleted mutant was weakened. Those PIP2 bindings of εPKC, εRD and the mutants well correlated to their neurite induction ability. In addition, a chimera of pleckstrin homology domain of phospholipase Cδ and the V3 region of εPKC revealed that PIP2 binding domain and the V3 region are sufficient for the neurite induction, and a first 16 amino acids in the V3 region was important for neurite extension. In conclusion, εPKC directly binds to PIP2 mainly through pseudo-substrate and common region 1, contributing to the neurite induction activity. © 2007 The Authors.