Ethanol negatively regulates hepatic differentiation of hESC by inhibition of the MAPK/ERK signaling pathway in vitro.
BACKGROUND
Alcohol insult triggers complex events in the liver, promoting fibrogenic/inflammatory signals and in more advanced cases, aberrant matrix deposition. It is well accepted that the regenerative capacity of the adult liver is impaired during alcohol injury. The liver progenitor/stem cells have been shown to play an important role in liver regeneration -in response to various chronic injuries; however, the effects of alcohol on stem cell differentiation in the liver are not well understood.


METHODS
We employed hepatic progenitor cells derived from hESCs to study the impact of ethanol on hepatocyte differentiation by exposure of these progenitor cells to ethanol during hepatocyte differentiation.


RESULTS
We found that ethanol negatively regulated hepatic differentiation of hESC-derived hepatic progenitor cells in a dose-dependent manner. There was also a moderate cell cycle arrest at G1/S checkpoint in the ethanol treated cells, which is associated with a reduced level of cyclin D1 in these cells. Ethanol treatment specifically inhibited the activation of the ERK but not JNK nor the p38 MAP signaling pathway. At the same time, the WNT signaling pathway was also reduced in the cells exposed to ethanol. Upon evaluating the effects of the inhibitors of these two signaling pathways, we determined that the Erk inhibitor replicated the effects of ethanol on the hepatocyte differentiation and attenuated the WNT/β-catenin signaling, however, inhibitors of WNT only partially replicated the effects of ethanol on the hepatocyte differentiation.


CONCLUSIONS
Our results demonstrated that ethanol negatively regulated hepatic differentiation of hESC-derived hepatic progenitors through inhibiting the MAPK/ERK signaling pathway, and subsequently attenuating the WNT signaling pathway. Thus, our finding provides a novel insight into the mechanism by which alcohol regulates cell fate selection of hESC-derived hepatic progenitor cells, and the identified pathways may provide therapeutic targets aimed at promoting liver repair and regeneration during alcoholic injury.
Department of Biomedical Engineering, College of Biology, Hunan University, Changsha, Hunan, China; Department of Internal Medicine, University of California Davis Medical Center, Sacramento, California, United States of America; Institute for Regenerative Cures, University of California Davis Medical Center, Sacramento, California, United States of America.
Wei
W
Gao
Department of Internal Medicine, University of California Davis Medical Center, Sacramento, California, United States of America; Institute for Regenerative Cures, University of California Davis Medical Center, Sacramento, California, United States of America.
Ping
P
Zhou
Department of Internal Medicine, University of California Davis Medical Center, Sacramento, California, United States of America; Institute for Regenerative Cures, University of California Davis Medical Center, Sacramento, California, United States of America.
Xiaocui
X
Ma
Department of Internal Medicine, University of California Davis Medical Center, Sacramento, California, United States of America; Institute for Regenerative Cures, University of California Davis Medical Center, Sacramento, California, United States of America.
Benjamin
B
Tschudy-Seney
Department of Internal Medicine, University of California Davis Medical Center, Sacramento, California, United States of America; Institute for Regenerative Cures, University of California Davis Medical Center, Sacramento, California, United States of America; Institute of Liver Diseases, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
Jiamei
J
Chen
Department of Internal Medicine, University of California Davis Medical Center, Sacramento, California, United States of America; Institute for Regenerative Cures, University of California Davis Medical Center, Sacramento, California, United States of America.
Nataly L
NL
Magner
Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America.
Alexander
A
Revzin
Department of Internal Medicine, University of California Davis Medical Center, Sacramento, California, United States of America; Institute for Regenerative Cures, University of California Davis Medical Center, Sacramento, California, United States of America.
Jan A
JA
Nolta
Department of Internal Medicine, University of California Davis Medical Center, Sacramento, California, United States of America; Institute for Regenerative Cures, University of California Davis Medical Center, Sacramento, California, United States of America.
Mark A
MA
Zern
Department of Internal Medicine, University of California Davis Medical Center, Sacramento, California, United States of America; Institute for Regenerative Cures, University of California Davis Medical Center, Sacramento, California, United States of America.
Yuyou
Y
Duan
D028341:Activins / Q000494:pharmacology; D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D019938:Cyclin D1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D061252:Feeder Cells; D005347:Fibroblasts / Q000166:cytology; D005786:Gene Expression Regulation; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007094:Imides / Q000494:pharmacology; D048670:MAP Kinase Kinase 4 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D015398:Signal Transduction; D051155:Wnt1 Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D051176:beta Catenin / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
D002070:Butadienes; C530104:CCND1 protein, human; C585534:IWR-1 compound; D007094:Imides; D009570:Nitriles; D011804:Quinolines; C113580:U 0126; C495247:WNT1 protein, human; D051155:Wnt1 Protein; C422405:activin A; D051176:beta Catenin; D028341:Activins; D019938:Cyclin D1; D000431:Ethanol; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4