NO/cGMP/PKG activation protects Drosophila cells subjected to hypoxic stress

Abstract The anoxia-tolerant fruit fly, Drosophila melanogaster , has routinely been used to examine cellular mechanisms responsible for anoxic and oxidative stress resistance. Nitric oxide (NO), an important cellular signaling molecule, and its downstream activation of cGMP-dependent protein kinase G (PKG) has been implicated as a protective mechanism against ischemic injury in diverse animal models from insects to mammals. In Drosophila , increased PKG signaling results in increased survival of animals exposed to anoxic stress. To determine if activation of the NO/cGMP/PKG pathway is protective at the cellular level, the present study employed a pharmacological protocol to mimic hypoxic injury in Drosophila S2 cells. The commonly used S2 cell line was derived from a primary culture of late stage (20–24 h old) Drosophila melanogaster embryos. Hypoxic stress was induced by exposure to either sodium azide (NaN 3 ) or cobalt chloride (CoCl 2 ). During chemical hypoxic stress, NO/cGMP/PKG activation protected against cell death and this mechanism involved modulation of downstream mitochondrial ATP-sensitive potassium ion channels (mitoK ATP ). The cellular protection afforded by NO/cGMP/PKG activation during ischemia-like stress may be an adaptive cytoprotective mechanism and modulation of this signaling cascade could serve as a potential therapeutic target for protection against hypoxia or ischemia-induced cellular injury.