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M, Ahmed S, Mantle D, Donohue TM Cook EB, Palmer TN, Simanowski UA, Seitz HK,
Peters TJ and Preedy VR. Effects
of Acute and Chronic Alcohol Treatment and Their Superimposition on Lysosomal,
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Chakkalakal
DA, Novak JR, Fritz ED, Mollner TJ, McVicker DL, Lybarger DL, McGuire MH,
Donohue TM. Chronic Ethanol
Consumption Results in Deficient Bone Repair in Rats.
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TM. The Ubiquitin-Proteasome System and its Role in Ethanol-Induced Disorders.
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J, McVicker, DL, Byrd, JC, MacDonald, RG, Donohue, TM. Chronic Ethanol
Administration Decreases the Ligand Binding Properties and the Cellular
Content of the Mannose-6-Phosphate/Insulin-like Growth Factor II Receptor in
Rat Hepatocytes. Biochemical Pharmacology 63:1229-1239 (2002).
Haorah,
J, Stoner,
J, Donohue, TM. Ethanol
Consumption Decreases the Synthesis of the Mannose 6-Phosphate/Insulin-Like
Growth Factor II Receptor but Does not Decrease its Messneger RNA. Biochemical
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637-648, 2003.
Osna,
N, Clemens, DL, Donohue, TM.
Interferon Gamma Enhances Proteasome Activity in Recombinant Hep G2 Cells
that Express Cytochrome P4502E1: Modulation by Ethanol. Biochemical Pharmacology
(in press).
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TM and Osna, NA. Role
of Intracellular Proteolytic Systems in Alcohol-Induced Tissue Injury. Alcohol
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TL, Nueller, C., Hamel, F.G., Chakkalakal, D, and Donohue, TM
The Effects of Chronic Alcohol Consumption on Dermal Penetration of
Pesticides in Rats. J. Toxicology and Environmental Health 67: 153-161
(2004).
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Kharbanda, KK, Casey, CA, and Nanji,
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Haorah, J, Heilman, D, Diekman, C, Osna,
N, Donohue, Jr. TM, Ghorpade, A, and Persidsky, Y.
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and French, S.W. The Ubiquitin-Proteasome System in Alcohol-Induced
Pathology in Comprehensive Handbook of Alcohol Related Pathology
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1027-1039 (2005).
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Enzymes. Alcoholism: Clin Exp Res 29: 1726-1734, 2005. Chakkalakal DA,
Novak JR, Fritz ED, Mollner TJ, McVicker DL, Garvin KL, McGuire MH and
Donohue TM,
Inhibition of bone repair in a rat model for chronic and excessive alcohol
consumption. Alcohol 36: 201-214, 2005.
Osna NA, Clemens DL and Donohue TM, Jr.,
Ethanol metabolism alters interferon gamma signaling recombinant hepg2 cells.
Hepatology 42: 1109-17, 2005.
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Ethanol Effects on
Proteolytic Systems in the Liver (Pending NIAAA-supported research)
These studies are
focused on how ethanol impairs protein degradation in liver cells.
Normal breakdown of proteins is necessary for cell survival. In the
liver, ethanol is converted to acetaldehyde and its metabolism can lead
to the generation of other compounds such as peroynitrite that react
with and can damage proteins, rendering them biologically inactive. We
wish to determine whether the ethanol-mediated impairments of the
protein degradative pathways in liver cells can significantly affect the
destruction of proteins altered by the products of ethanol oxidation.
One major focus in this investigation will be on a degradative pathway
known as the ubiquitin-proteasome pathway (UPP), which specifically
disposes of damaged proteins in the cell. This pathway has an essential
role in a variety of cell functions, including programmed cell death and
the regulation of gene expression. We have postulated that, because the
level of certain transcription factors is modulated by the UPP, that its
inhibition by ethanol may influence changes such as ethanol-elicited
steatosis (fatty liver). Experiments are currently underway to determine
this possibility.
Potential Student
Projects:
To
determine whether nitration induced in vitro and by ethanol
consumption in vivo can influence the activity of the proteasome.
To
examine whether proteasome inhibition by ethanol enhances the activities
and levels of the transcription factors SREBP-1 and Egr-1, both of which
are involved in ethanol-elicited steatosis.
To
examine whether ethanol consumption impairs the ubiquitin-proteasome
system in vivo in transgenic mice and whether this impairment
leads to liver injury.
Proteolysis and
Ethanol Induced Oxidative Stress in Cultured Hepatoma Cells
(VA-supported research)
The aim of this
investigation is to use parental and recombinant cultured hepatoma
cells, with varying capacities to metabolize ethanol, to determine
whether ethanol metabolism is responsible for ethanol-induced changes in
protein metabolism, previously observed in intact animals. We possess a
number of HepG2 cell lines (human hepatoblastoma cells) that express
either or both alcohol dehydrogenase and cytochrome-P450 2E1 (CYP2E1).
We also possess cell lines that are inducble for CYP2E1. These cell
lines show demonstrable differences in their rates of ethanol
metabolism, which, in turn is related to similar degrees of toxic
responses to ethanol. Our hypothesis is that ethanol-induced impairments
in protein metabolism can result in greater toxicity to ethanol
metabolizing cells because the rate of protein turnover is altered,
thereby resulting in the accumulation of altered proteins, which are
potentially toxic to the cell.
Potential Student
Projects:
To
establish whether protein aggregates that form in response to ethanol
are effective substrates or inhibitors of the proteasome and whether
such aggregates cause cell death.
To
investigate whether ethanol metabolism sensitizes HepG2 cells to
induction of apoptosis by the pro-inflammatory cytokines, TNFα and
IFNγ.
To
determine whether ethanol exposure disrupts the insulin-induced
reduction of proteolysis in parental and recombinant Hep G2 cells.
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