The Dose-Dependent Effect of Ethanol on sAPPα Secretion from CHO695 Cells
Abstract
Alcohol is an immunosuppressive drug that has been found to have an
inhibitory effect on immune responses. Previous researchers have shown
the inhibitory effect of EtOH on TNF-alpha secretion. With the intense
study of EtOH’s effect on the secretion of TNF-alpha, the interest of the
effect of EtOH on the brain has been instigated. APP, the amyloid
precursor protein, is a significant nervous system and transmembrane
protein found in the brain and is under study due to the formation of Aβ
plaques in the brain during the onset of Alzheimer’s disease. Through the
study of Alzheimer’s patients, a further understanding of APP in the brain
has been assessed.
TACE, TNF-alpha converting enzyme, is important in both proteins of
interest, APP and TNF. TACE is an α-secretase that is effected by the
addition of various concentrations of EtOH. and is involved in a
posttranscriptional process called ectodomain shedding. Levels of APP
substrate in the brain are affected by the levels of EtOH.
This study consisted of determining the effects of ethanol on the
secretion of sAPP-alpha with the presence and absence of PMA, Phorbol
12-Myristate 13-Acetate, a TACE stimulator. Chinese Hamster Ovary
cells, CHO695, cells were grown in Dulbecco’s Modified Eagle Medium,
DMEM and incubated in ethanol concentrations varying from 0, 5, 10, 15,
25, to lethal doses of EtOH at 75mM. The results of the conducted study
showed a dose-dependent decrease in sAPP-alpha secretion. These
results support the prediction that the levels of sAPP-alpha would
decrease as EtOHconcentrations increased. There was no general
change in cellular APP levels with increasing EtOH. However, at lethal
doses of EtOH, 75 mM, the cellular APP was completely degraded,
therefore making sAPP-alpha secretion unattainable. By further studying
the effect of alcohol on the secretion of sAPP-alpha, we plan on defining
its role in brain function. The results of the experiment illustrated that at
high levels of EtOH concentrations, the substrate, APP, is completely
degraded. Without the presence of APP, sAPP-alpha cannot be secreted.