Liver proteomics

A proteomic profiling strategy examined the effects of ethanol and betaine diet supplementation on major liver protein level changes. Male Wistar rats were fed control, ethanol or betaine supplemented diets for 4 weeks. Livers were removed and liver cytosolic proteins resolved by one-dimensional and two-dimensional separation techniques.

In rats fed the betaine supplemented ethanol diet, there was significant upregulation of:

- betaine homocysteine methyltransferase-1
- methionine adenosyl transferase-1
- glycine N-methyltransferase

The authors hypothesise that this concerted upregulation of these methionine metabolic pathway enzymes is the protective mechanism by which betaine restores a normal metabolic ratio of liver S-adenosylmethionine to S-adenosylhomocysteine. Ethanol also induced significant downregulation of carbonic anhydrase-III protein levels which was not restored by betaine supplementation. Carbonic anhydrase-III can function to resist oxidative stress, and the authors hypothesise that carbonic anhydrase-III protein levels compromised by ethanol consumption, contribute to ethanol-induced redox stress.

Kharbanda et al (2009). "Proteomics reveal a concerted upregulation of methionine metabolic pathway enzymes, and downregulation of carbonic anhydrase-III, in betaine supplemented ethanol-fed rats." Biochem Biophys Res Commun 381(4): 523-7.