Selective activation of protein kinase C isoforms by angiotensin II in neuroblastoma X glioma cells

Abstract

Differential activation of PKC isoforms by angiotensin II (AII) has been found in a variety of tissues in which this important octapeptide mediates its multitude of effects. To date, the PKC isoforms involved in mediating brain-specific effects are yet to be defined. In the present study, the identity of PKC isoforms coupled to AII stimulation was examined in the neuroblastoma X glioma hybrid cell line, NG108-15, by Western blot analysis. This cell line expresses both the AT1 and AT2 receptor subtypes, with the AT1 subtype predominating, and expression levels highly-upregulated when cells are in the differentiated state. Six PKC isoforms were examined in the present study, including three Ca 2+ dependent (α, β, and γ), and three Ca 2+ independent (δ, ε, and ζ) isoforms. NG108-15 cells were found to express PKC α, δ, ε, and ζ isoforms but not β or γ isoforms. Differential sensitivity of the PKC isoforms to AII stimulation was demonstrated, with AII causing a rapid and transient activation of the PKC α only in undifferentiated cells, whereas both PKC α and ε isoforms were responsive in differentiated cells. PKC activation was found to be both dose- and time-dependent. The data demonstrate the differential activation of PKC isoforms to AII stimulation in NG108-15 cells, with evidence supporting the involvement of the PKC α and ε isoforms in AII-mediated effects in the brain.