TY - JOUR
T1 - Increased mitochondrial ROS formation by acetaminophen in human hepatic cells is associated with gene expression changes suggesting disruption of the mitochondrial electron transport chain
AU - Jiang, Jian
AU - Briede, Jacob J.
AU - Jennen, Danyel G. J.
AU - Van Summeren, Anke
AU - Saritas-Brauers, Karen
AU - Schaart, Gert
AU - Kleinjans, Jos C. S.
AU - de Kok, Theo M. C. M.
PY - 2015/4/16
Y1 - 2015/4/16
N2 - Acetaminophen (APAP) overdosage results in hepatotoxicity, but the underlying molecular mechanisms are still not completely understood. In the current study, we focused on mitochondrial-specific oxidative liver injury induced by APAP exposure. Owning to genetic polymorphisms in the CYP2E1 gene or varying inducibility by xenobiotics, the CYP2E1 mRNA level and protein activity vary extensively among individuals. As CYP2E1 is a known ROS generating enzyme, we chose HepG2 to minimize CYP2E1-induced ROS formation, which will help us better understand the APAP induced mitochondrial-specific hepatotoxicity in a subpopulation with low CYP2E1 activity. HepG2 cells were exposed to a low and toxic dose (0.5 and 10mM) of APAP and analyzed at four time points for genome-wide gene expression. Mitochondria were isolated and electron spin resonance spectroscopy was performed to measure the formation of mitochondrial ROS. The yield of ATP was measured to confirm the impact of the toxic dose of APAP on cellular energy production. Our results indicate that 10mM APAP significantly influences the expression of mitochondrial protein-encoding genes in association with an increase in mitochondrial ROS formation. Additionally, 10mM APAP affects the expression of genes encoding the subunits of electron transport chain (ETC) complexes, which may alter normal mitochondrial functions by disrupting the assembly, stability, and structural integrity of ETC complexes, leading to ameasurable depletion of ATP, and cell death. The expression of mitochondrium specific antioxidant enzyme, SOD2, is reduced which may limit the ROS scavenging ability and cause imbalance of themitochondrial ROS homeostasis. Overall, transcriptome analysis reveals themolecular processes involved in the observed APAP-induced increase of mitochondrial ROS formation and the associated APAP-induced oxidative stress.
AB - Acetaminophen (APAP) overdosage results in hepatotoxicity, but the underlying molecular mechanisms are still not completely understood. In the current study, we focused on mitochondrial-specific oxidative liver injury induced by APAP exposure. Owning to genetic polymorphisms in the CYP2E1 gene or varying inducibility by xenobiotics, the CYP2E1 mRNA level and protein activity vary extensively among individuals. As CYP2E1 is a known ROS generating enzyme, we chose HepG2 to minimize CYP2E1-induced ROS formation, which will help us better understand the APAP induced mitochondrial-specific hepatotoxicity in a subpopulation with low CYP2E1 activity. HepG2 cells were exposed to a low and toxic dose (0.5 and 10mM) of APAP and analyzed at four time points for genome-wide gene expression. Mitochondria were isolated and electron spin resonance spectroscopy was performed to measure the formation of mitochondrial ROS. The yield of ATP was measured to confirm the impact of the toxic dose of APAP on cellular energy production. Our results indicate that 10mM APAP significantly influences the expression of mitochondrial protein-encoding genes in association with an increase in mitochondrial ROS formation. Additionally, 10mM APAP affects the expression of genes encoding the subunits of electron transport chain (ETC) complexes, which may alter normal mitochondrial functions by disrupting the assembly, stability, and structural integrity of ETC complexes, leading to ameasurable depletion of ATP, and cell death. The expression of mitochondrium specific antioxidant enzyme, SOD2, is reduced which may limit the ROS scavenging ability and cause imbalance of themitochondrial ROS homeostasis. Overall, transcriptome analysis reveals themolecular processes involved in the observed APAP-induced increase of mitochondrial ROS formation and the associated APAP-induced oxidative stress.
KW - Toxicogenomics
KW - Acetaminophen
KW - HepG2
KW - Microarray
KW - ESR
KW - Mitochondrial ROS
U2 - 10.1016/j.toxlet.2015.02.012
DO - 10.1016/j.toxlet.2015.02.012
M3 - Article
C2 - 25704631
SN - 0378-4274
VL - 234
SP - 139
EP - 150
JO - Toxicology Letters
JF - Toxicology Letters
IS - 2
ER -