Over-expression of mitochondrial heat shock protein 70 suppresses programmed cell death in rice

In this study, we identified and functionally characterized the mitochondrial heat shock protein 70 (mtHsp70). Over-expression of mtHsp70 suppressed heat-and H2O2-induced programmed cell death (PCD) in rice protoplasts, as reflected by higher cell viability, decreased DNA laddering and chromatin condensation. Mitochondrial membrane potential (Delta psi(m)) after heat shock was destroyed gradually in protoplasts, but mtHsp70 over-expression showed higher Delta psi(m) relative to the vector control cells, and partially inhibited cytochrome c release from mitochondria to cytosol. Heat treatment also significantly increased reactive oxygen species (ROS) generation, a phenomenon not observed in protoplasts over-expressing mtHsp70. Together, these results suggest that mtHsp70 may suppress PCD in rice protoplasts by maintaining mitochondrial Delta psi(m) and inhibiting the amplification of ROS. (C) 2010 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.