TY - JOUR
T1 - FAT10 suppression stabilizes oxidized proteins in liver cells
T2 - Effects of HCV and ethanol
AU - Ganesan, Murali
AU - Hindman, Joseph
AU - Tillman, Brittany
AU - Jaramillo, Lee
AU - Poluektova, Larisa Y
AU - French, Barbara A.
AU - Kharbanda, Kusum
AU - French, Samuel W.
AU - Osna, Natalia A
N1 - Funding Information:
We thank Dr. Steven Weinman for providing HCV + Tg mice and Dr. Terrence Donohue for helping with mouse gavaging. This study was funded by BLR&D Merit Review Award ( 1 101BX001673-01A1 ).
Publisher Copyright:
© 2015.
PY - 2015/12/1
Y1 - 2015/12/1
N2 - FAT10 belongs to the ubiquitin-like modifier (ULM) family that targets proteins for degradation and is recognized by 26S proteasome. FAT10 is presented on immune cells and under the inflammatory conditions, is synergistically induced by IFNγ and TNFα in the non-immune (liver parenchymal) cells. It is not clear how viral proteins and alcohol regulate FAT10 expression on liver cells. In this study, we aimed to investigate whether FAT10 expression on liver cells is activated by the innate immunity factor, IFNα and how HCV protein expression in hepatocytes and ethanol-induced oxidative stress affect the level of FAT10 in liver cells. For this study, we used HCV+ transgenic mice that express structural HCV proteins and their HCV- littermates. Mice were fed Lieber De Carli diet (control and ethanol) as specified in the NIH protocol for chronic-acute ethanol feeding. Alcohol exposure enhanced steatosis, induced oxidative stress and decreased proteasome activity in the liversof these mice, with more robust response to ethanol in HCV+ mice. IFNα induced transcriptional activation of FAT10 in liver cells, which was dysregulated by ethanol feeding. Accordingly, IFNα-activated expression of FAT10 in hepatocytes (measured by indirect immunofluorescent of liver tissue) was also suppressed by ethanol exposure in both HCV+ and HCV- mice. This suppression was accompanied with ethanol-mediated induction of lipid peroxidation marker, 4-HNE. All aforementioned effects of ethanol were attenuated by in vivo feeding of mice with the pro-methylating agent, betaine, which exhibits strong anti-oxidant properties. Based on this study, we hypothesize that FAT10 targets oxidatively modified proteins for proteasomal degradation, and that the reduction in FAT10 levels along with decreased proteasome activity may contribute to stabilization of these altered proteins in hepatocytes. In conclusion, IFNα induced FAT10 expression, which is suppressed by ethanol feeding in both HCV+ and HCV- mice. Betaine treatment reverses HCV-ethanol induced dysregulation of protein methylation and oxidative stress, thereby restoring the FAT10 expression on liver cells.
AB - FAT10 belongs to the ubiquitin-like modifier (ULM) family that targets proteins for degradation and is recognized by 26S proteasome. FAT10 is presented on immune cells and under the inflammatory conditions, is synergistically induced by IFNγ and TNFα in the non-immune (liver parenchymal) cells. It is not clear how viral proteins and alcohol regulate FAT10 expression on liver cells. In this study, we aimed to investigate whether FAT10 expression on liver cells is activated by the innate immunity factor, IFNα and how HCV protein expression in hepatocytes and ethanol-induced oxidative stress affect the level of FAT10 in liver cells. For this study, we used HCV+ transgenic mice that express structural HCV proteins and their HCV- littermates. Mice were fed Lieber De Carli diet (control and ethanol) as specified in the NIH protocol for chronic-acute ethanol feeding. Alcohol exposure enhanced steatosis, induced oxidative stress and decreased proteasome activity in the liversof these mice, with more robust response to ethanol in HCV+ mice. IFNα induced transcriptional activation of FAT10 in liver cells, which was dysregulated by ethanol feeding. Accordingly, IFNα-activated expression of FAT10 in hepatocytes (measured by indirect immunofluorescent of liver tissue) was also suppressed by ethanol exposure in both HCV+ and HCV- mice. This suppression was accompanied with ethanol-mediated induction of lipid peroxidation marker, 4-HNE. All aforementioned effects of ethanol were attenuated by in vivo feeding of mice with the pro-methylating agent, betaine, which exhibits strong anti-oxidant properties. Based on this study, we hypothesize that FAT10 targets oxidatively modified proteins for proteasomal degradation, and that the reduction in FAT10 levels along with decreased proteasome activity may contribute to stabilization of these altered proteins in hepatocytes. In conclusion, IFNα induced FAT10 expression, which is suppressed by ethanol feeding in both HCV+ and HCV- mice. Betaine treatment reverses HCV-ethanol induced dysregulation of protein methylation and oxidative stress, thereby restoring the FAT10 expression on liver cells.
KW - Betaine
KW - Ethanol
KW - FAT10
KW - HCV
KW - Oxidative stress
KW - Ubiquitylation
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U2 - 10.1016/j.yexmp.2015.09.009
DO - 10.1016/j.yexmp.2015.09.009
M3 - Article
C2 - 26407761
AN - SCOPUS:84943147871
SN - 0014-4800
VL - 99
SP - 506
EP - 516
JO - Experimental and Molecular Pathology
JF - Experimental and Molecular Pathology
IS - 3
ER -