Figure 2.

The propagation phase of acetaminophen-induced cell death. Mitochondrial dysfunction is central to APAP pathophysiology: Activation of JNK in the cytosol and its translocation to the mitochondria initiates a vicious cycle of mitochondrial distress, where inhibition of mitochondrial electron transport enhances reactive oxygen generation and formation of peroxynitrite, which cause mitochondrial oxidative and nitrosative stress. This in turn further amplifies the cytosolic MAP kinase cascade activating JNK and maintaining its translocation to the mitochondria. Persistent mitochondrial oxidative and nitrosative stress evidenced by increase in glutathione disulfide (GSSG) and peroxynitrite, coupled with BAX translocation to the mitochondria ultimately induce the mitochondrial permeability transition (MPT). This results in release of mitochondrial proteins such as SMAC, cytochrome c, apoptosis inducing factor (AIF) and endonuclease G (ENDOG) into the cytosol. AIF and ENDOG translocate to the nucleus to induce DNA fragmentation and ultimately hepatocyte necrosis. These well-defined steps in APAP pathophysiology allow their examination by evaluating JNK and BAX as well as glutathione disulfide and nitrotyrosine protein adducts (as marker of peroxynitrite formation) in mitochondrial fractions (green boxes) which would provide mechanistically relevant information rather than their analysis in the whole liver. Likewise, examination of mitochondrial proteins such as AIF in the cytosolic fraction provide information on activation of the MPT in vivo. This figure includes templates from Servier Medical Art, which is licensed under a Creative Commons Attribution 3.0 generic license; https://smart.servier.com.