1.Silencing MAT2A gene by RNA interference inhibited cell growth and induced apoptosis in human hepatoma cells.
Liu Q1, Wu K, Zhu Y, He Y, Wu J, Liu Z. Hepatol Res. 2007 May;37(5):376-88.
AIMS: A switch in gene expression from MAT1A to MAT2A was found in liver cancer, suggesting that MAT2A plays an important role in facilitating cancer growth. MAT2A is an interesting target for antineoplastic therapy. The molecular mechanisms of silencing MAT2A by RNA interference inhibited cell growth and induced apoptosis in hepatoma cells was studied.
2.Acute effects of ethionine stereoisomers on hepatic RNA and protein synthesis in swiss mice.
Berry DE, Friedman MA. Cancer Biochem Biophys. 1976 Aug;1(5):245-50.
The acute biochemical effects of ethionine have been well studied in rats but not in mice. These results show that both hepatic RNA and protein synthesis in Swiss mice were inhibited by DL-ethionine. Protein synthesis was inhibited 30 to 40 percent 3 hr after 2500 mg/kg DL-ethionine while RNA synthesis was inhibited 80 to 90 percent 3 hr after 625 mg/kg DL-ethionine. Thus ethionine was a far more potent inhibitor of RNA synthesis than of protein synthesis. There was no sex difference in either of these responses. While both stereoisomers were active, the L isomer was a more potent inhibitor of RNA synthesis than was the D isomer. In male mice, 3 hr after 20 mg/kg L-ethionine, RNA synthesis was inhibited 80%, while after D-ethionine it was inhibited only 51%.
3.Characterization of prolidase I and II purified from normal human erythrocytes: comparison with prolidase in erythrocytes from a patient with prolidase deficiency.
Uramatsu S1, Liu G, Yang Q, Uramatsu M, Chi H, Lu J, Yamashita K, Kodama H. Amino Acids. 2009 Sep;37(3):543-51. doi: 10.1007/s00726-009-0262-7. Epub 2009 Mar 5.
The effect of various sulfur-containing amino acids on the activities of prolidase isoenzymes I and II isolated from erythrocytes of healthy individuals, and erythrocyte lysates from a patient with prolidase deficiency was investigated. The activity of prolidase I against glycylproline was strongly enhanced by D: -methionine. L: -Methionine and D: ,L: -methionine slightly enhanced the activity at low concentration, but N-acetyl-L: -methionine had no effect. D: -Ethionine, L: -ethionine, and D: ,L: -ethionine also enhanced the activity of prolidase I. D: ,L: -Homocysteine enhanced the activity at low concentration, but inhibited the activity at 50 mM: . The activity of prolidase II against methionylproline was enhanced by D: -methionine, D: ,L: -methionine, and L: -methionine, but N-acetyl-L: -methionine had no effect. D: -Ethionine and D: ,L: -ethionine strongly enhanced the activity of prolidase II compared with L: -ethionine; D: ,L: -homocysteine weakly enhanced the activity.
4.S-adenosylmethionine regulates MAT1A and MAT2A gene expression in cultured rat hepatocytes: a new role for S-adenosylmethionine in the maintenance of the differentiated status of the liver.
García-Trevijano ER1, Latasa MU, Carretero MV, Berasain C, Mato JM, Avila MA. FASEB J. 2000 Dec;14(15):2511-8.
Methionine metabolism starts with the formation of S-adenosylmethionine (AdoMet), the most important biological methyl donor. This reaction is catalyzed by methionine adenosyltransferase (MAT). MAT is the product of two different genes: MAT1A, which is expressed only in the adult liver, and MAT2A, which is widely distributed, expressed in the fetal liver, and replaces MAT1A in hepatocarcinoma. In the liver, preservation of high expression of MAT1A and low expression of MAT2A is critical for the maintenance of a functional and differentiated organ. Here we describe that in cultured rat hepatocytes MAT1A expression progressively decreased, as described for other liver-specific genes, and MAT2A expression was induced. We find that this switch in gene expression was prevented by adding AdoMet to the culture medium. We also show that in cultured hepatocytes with decreased MAT1A expression AdoMet addition markedly increased MAT1A transcription in a dose-dependent fashion.
