Changes in methionine adenosyltransferase during liver regeneration in the rat
Changes in methionine adenosyltransferase during liver regeneration in the rat
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DOI：
10.1152/ajpgi.1998.275.1.g14
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发表时间：
1998-07-01
影响因子：
4.5
通讯作者：
Lu, SC
中科院分区：
文献类型：
--
作者：
Huang, ZZ;Mao, ZB;Lu, SC
肝特异性和非肝特异性甲硫氨酸腺苷转移酶（MAT）是两个基因（分别为MAT 1A和MAT 2A）的产物，催化主要甲基供体S-腺苷甲硫氨酸（SAM）的形成。我们先前表明，MAT 2A表达与更快的细胞生长有关。在这里，我们研究了三分之二部分肝切除术（PH）后大鼠肝脏MAT基因表达的变化和相关后果。两种MAT形式的mRNA水平从3小时增加到6小时，但MAT 1A水平从12小时下降到24小时低于基线，而MAT 2A水平在PH后4天仍保持升高。MAT 2A mRNA水平的增加是由于基因转录和mRNA稳定性增加。MAT 1A mRNA水平的变化是转录后的，不需要从头蛋白质合成。MAT活性的变化与MAT同工酶数量的增加一致。SAM水平、SAM与S-腺苷高半胱氨酸（SAH）的比率和DNA甲基化从6至24小时下降，而SAH水平在PH后12和24小时略有增加。SAM利用率和MAT 2A基因表达的增加可能导致SAM下降。
Liver-specific and non-liver-specific methionine adenosyltransferase (MAT) are products of two genes (MAT1A and MAT2A, respectively) that catalyze the formation of S-adenosylmethionine (SAM), the principal methyl donor. We previously showed that MAT2A expression was associated with more rapid cell growth. Here we examined changes in hepatic MAT gene expression and related consequences after two-thirds partial hepatectomy (PH) in rats. The mRNA levels of both MAT forms increased from 3 to 6 h, but the MAT1A level then fell below baseline from 12 to 24 h, whereas the MAT2A level remained elevated up to 4 days after PH. The increase in the MAT2A mRNA level was due to increased gene transcription and mRNA stabilization. The change in the MAT1A mRNA level was posttranscriptional and did not require de novo protein synthesis. Changes in MAT activity were consistent with an increased amount of MAT isozymes. SAM levels, the ratio of SAM to S-adenosylhomocysteine (SAH), and DNA methylation fell from 6 to 24 h, whereas SAH levels increased slightly at 12 and 24 h after PH. Both increased SAM utilization and MAT2A gene expression Likely contributed to the fall in SAM.