TY - JOUR
T1 - Augmented Liver Uptake of the Membrane Voltage Sensor Tetraphenylphosphonium Distinguishes Early Fibrosis in a Mouse Model
AU - Pandita, Himanshi
AU - Mezey, Esteban
AU - Ganapathy-Kanniappan, Shanmugasundaram
N1 - Funding Information:
We thank Edmond Jacobs for the help in the tail-vein injection of 3H-TPP. We also thank Michelle-Acoba and Dr. Steven Claypool for the help in Seahorse metabolic flux analyzer. We sincerely acknowledge the help provided by Barbara Smith of Electron Microscope Facility, School of Medicine in TEM image acquisition, and Prof. Norman Barker of the Department of Pathology for the help in photomicrography of histopathology slides. We acknowledge the support from the Willis C. Maddrey endowment for liver research at Johns Hopkins and the Bright Star award (SG-K) from the Radiology department.
Publisher Copyright:
Copyright © 2021 Pandita, Mezey and Ganapathy-Kanniappan.
PY - 2021/10/25
Y1 - 2021/10/25
N2 - Mitochondrial (mito-) oxidative phosphorylation (OxPhos) is a critical determinant of cellular membrane potential/voltage. Dysregulation of OxPhos is a biochemical signature of advanced liver fibrosis. However, less is known about the net voltage of the liver in fibrosis. In this study, using the radiolabeled [3H] voltage sensor, tetraphenylphosphonium (TPP), which depends on membrane potential for cellular uptake/accumulation, we determined the net voltage of the liver in a mouse model of carbon tetrachloride (CCl4)-induced hepatic fibrosis. We demonstrated that the liver uptake of 3H-TPP significantly increased at 4 weeks of CCl4-administration (6.07 ± 0.69% ID/g, p < 0.05) compared with 6 weeks (4.85 ± 1.47% ID/g) and the control (3.50 ± 0.22% ID/g). Analysis of the fibrosis, collagen synthesis, and deposition showed that the increased 3H-TPP uptake at 4 weeks corresponds to early fibrosis (F1), according to the METAVIR scoring system. Biodistribution data revealed that the 3H-TPP accumulation is significant in the fibrogenic liver but not in other tissues. Mechanistically, the augmentation of the liver uptake of 3H-TPP in early fibrosis concurred with the upregulation of mito-electron transport chain enzymes, a concomitant increase in mito-oxygen consumption, and the activation of the AMPK-signaling pathway. Collectively, our results indicate that mito-metabolic response to hepatic insult may underlie the net increase in the voltage of the liver in early fibrosis.
AB - Mitochondrial (mito-) oxidative phosphorylation (OxPhos) is a critical determinant of cellular membrane potential/voltage. Dysregulation of OxPhos is a biochemical signature of advanced liver fibrosis. However, less is known about the net voltage of the liver in fibrosis. In this study, using the radiolabeled [3H] voltage sensor, tetraphenylphosphonium (TPP), which depends on membrane potential for cellular uptake/accumulation, we determined the net voltage of the liver in a mouse model of carbon tetrachloride (CCl4)-induced hepatic fibrosis. We demonstrated that the liver uptake of 3H-TPP significantly increased at 4 weeks of CCl4-administration (6.07 ± 0.69% ID/g, p < 0.05) compared with 6 weeks (4.85 ± 1.47% ID/g) and the control (3.50 ± 0.22% ID/g). Analysis of the fibrosis, collagen synthesis, and deposition showed that the increased 3H-TPP uptake at 4 weeks corresponds to early fibrosis (F1), according to the METAVIR scoring system. Biodistribution data revealed that the 3H-TPP accumulation is significant in the fibrogenic liver but not in other tissues. Mechanistically, the augmentation of the liver uptake of 3H-TPP in early fibrosis concurred with the upregulation of mito-electron transport chain enzymes, a concomitant increase in mito-oxygen consumption, and the activation of the AMPK-signaling pathway. Collectively, our results indicate that mito-metabolic response to hepatic insult may underlie the net increase in the voltage of the liver in early fibrosis.
KW - carbon tetrachloride
KW - electron transport chain
KW - liver fibrosis
KW - liver voltage
KW - membrane-voltage sensor
KW - mitochondrial respiration
KW - tetraphenylphosphonium (TPP)
UR - http://www.scopus.com/inward/record.url?scp=85118787633&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85118787633&partnerID=8YFLogxK
U2 - 10.3389/fphys.2021.676722
DO - 10.3389/fphys.2021.676722
M3 - Article
C2 - 34759830
AN - SCOPUS:85118787633
SN - 1664-042X
VL - 12
JO - Frontiers in Physiology
JF - Frontiers in Physiology
M1 - 676722
ER -