Proteasome function is required for activation of programmed cell death in heat shocked tobacco Bright-Yellow 2 cells

Abstract 

To find out whether and how proteasome is involved in plant programmed cell death (PCD) we measured proteasome function in tobacco cells undergoing PCD as a result of heat shock (HS-PCD). Reactive oxygen species (ROS) production, cytochrome c levels and caspase-3-like protease activation were also measured in the absence or presence of MG132, a proteasome inhibitor. We show that proteasome activation occurs in early phase of HS-PCD upstream of the caspase-like proteases activation; moreover inhibition of proteasome function by MG132 results in prevention of PCD perhaps due to the prevention of ROS production, cytochrome c release and caspase-3-like protease activation.

Abbreviations: PCD, programmed cell death, HS-PCD, programmed cell death induced by heat shock, MG132-HS cells, MG132-treated heat shocked cells, ROS, reactive oxygen species, cyt c, cytochrome c, cAPX, cytosolic ascorbate peroxidase, mGDH, mitochondrial glutamate dehydrogenase

Keywords: Plant programmed cell death, Proteasome, Reactive oxygen species, Cytosolic ascorbate peroxidase, Cytochrome c, Caspase-like proteases