Translocation of protein kinase C-α, δ and ϵ isoforms in ischemic rat heart

AbstractTo explore the spatial and temporal localization of PKC isoforms during ischemia, we quantified PKC isoforms in the subcellular fractions in perfused rat heart by immunoblotting using specific antibodies against PKC isoforms. PKCs-α and ϵ translocated from the 100 000 × g supernatant (S, cytosolic) fraction to the 1000 × g pellet (P1, nucleus-myofibril) and the 1000−100000 × g pellet (P2, membrane) fractions during 5–40 min of ischemia. PKC-δ redistributed from the P2 to the S fraction. A 50-kDa fragment of PKC-α appeared during ischemia possibly through calpain action. Immunohistochemical observations showed the different localizations of PKC-α, δ, and ϵ in the myocytes. The PKC assay displayed high basal levels of Ca2+-independent PKC, the activation of Ca2+-dependent PKC in the P1 and P2 fractions, and the activation of Ca2+-independent PKC in the P1 fraction after 20 min of ischemia. These observations show that ischemia induces different patterns of translocation of the three PKC isoforms, suggesting differences in their roles