Role of transmethylation reactions in alcoholic liver disease

作     者：Kusum K Kharbanda 

作者机构：VA Alcohol Research Center Department of Veterans Affairs Medical Center Omaha Nebraska 68105 United States Department of Internal Medicine University of Nebraska Medical Center Omaha Nebraska 68198 United States 

出 版 物：《World Journal of Gastroenterology》 (世界胃肠病学杂志（英文版）)

年 卷 期：2007年第13卷第37期

页      面：4947-4954页

核心收录：

学科分类：1002[医学-临床医学] 100201[医学-内科学(含：心血管病、血液病、呼吸系病、消化系病、内分泌与代谢病、肾病、风湿病、传染病)] 10[医学] 

基　　金：Supported by the VA Merit Review from the Department of Veterans Affairs 

主　　题：Transmethylation S-adenosylhomocysteine Alcohol Betaine Liver Steatosis Apoptosis Methyltransferases 

摘      要：Alcoholic liver disease is a major health care problem worldwide. Findings from many laboratories, including ours, have demonstrated that ethanol feeding impairs several of the many steps involved in methionine metabolism. Ethanol consumption predominantly results in a decrease in the hepatocyte level of S-adenosylmethionine and the increases in two toxic metabolites, homocysteine and S-adenosylhomocysteine. These changes, in turn, result in serious functional consequences which include decreases in essential methylation reactions v/a inhibition of various methyltransferases. Of particular interest to our laboratory is the inhibition of three important enzymes, phosphatidylethanolamine methyltransferase, isoprenylcysteine carboxyl methyltransferase and protein L-isoaspartate methyltransferase. Decreased activity of these enzymes results in increased fat deposition, increased apoptosis and increased accumulation of damaged proteins- all of which are hallmark features of alcoholic liver injury. Of all the therapeutic modalities available, betaine has been shown to be the safest, least expensive and most effective in attenuating ethanol-induced liver injury. Betaine, by virtue of aiding in the remethylation of homocysteine, removes both toxic metabolites （homocysteine and S-adenosylhomocysteine）, restores S-adenosylmethionine level, and reverses steatosis, apoptosis and damaged proteins accumulation. In conclusion, betaine appears to be a promising therapeutic agent in relieving the methylation and other defects associated with alcoholic abuse.