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.