Post-transcriptional regulation of cysteine dioxygenase in rat liver.
Post-transcriptional regulation of cysteine dioxygenase in rat liver.
复制标题
大鼠肝脏半胱氨酸双加氧酶的转录后调节。
DOI：
10.1007/0-306-46838-7_7
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发表时间：
2000
影响因子：
--
通讯作者：
Stipanuk,MH
中科院分区：
文献类型：
--
作者：
Bella,DL;Kwon,YH;Hirschberger,LL;Stipanuk,MH
肝脏半胱氨酸双加氧酶（CDO）活性的变化在半胱氨酸催化剂和牛磺酸合成的调节中起主导作用。我们对大鼠肝脏和大鼠肝细胞中CDO活性的分子调节进行了几项研究。与在喂食基础10%酪蛋白饮食的大鼠肝脏中观察到的水平相比，在喂食含有额外蛋白质、完全氨基酸混合物、甲硫氨酸或胱氨酸的饮食的大鼠肝脏中观察到高达180倍的CDO活性和蛋白质水平5，6。无论是CDO活性，也不CDO蛋白诱导过量的非硫氨基酸单独。过量的含硫氨基酸或蛋白质并没有显着增加肝CDO mRNA的浓度。初步研究表明，CDO mRNA与多聚核糖体的关联的多聚核糖体配置文件是不改变饮食中蛋白质水平的增加，这表明，调节可能是翻译后，并可能涉及减少CDO降解率。在大鼠肝细胞的原代培养物中，在标准培养基中培养12至24小时后，CDO mRNA、蛋白质和活性几乎全部消失14，而在含有过量甲硫氨酸或半胱氨酸的培养基中培养的肝细胞中，CDO蛋白质（而非CDO mRNA）在12至24小时之间显著积累。这些观察结果也是一致的CDO的转录或翻译调节响应饮食的有限作用。
Changes in hepatic cysteine dioxygenase (CDO) activity in response to diet play a dominant role in regulation of cysteine catabolism and taurine synthesis. We have conducted several studies of the molecular regulation of CDO activity in rat liver and rat hepatocytes. Compared to levels observed in liver of rats fed a basal 10% casein diet, up to 180-fold higher levels of CDO activity and protein were observed in liver of rats fed diets that contained additional protein, complete amino acid mixture, methionine, or cystine5,6. Neither CDO activity nor CDO protein was induced by excess non-sulfur amino acids alone. Excess sulfur amino acids or protein did not significantly increase the concentration of hepatic CDO mRNA. Preliminary studies indicate that the polysome profile for association of CDO mRNA with polysomes is not altered by an increase in dietary protein level, suggesting that regulation may be posttranslational and possibly involve a decrease in the rate of CDO degradation. In primary cultures of rat hepatocytes, CDO mRNA, protein, and activity all virtually disappeared by 12 to 24 h of culture in standard medium14 whereas CDO protein, but not CDO mRNA, accumulated markedly between 12 and 24 h in hepatocytes cultured in medium with excess methionine or cyst(e)ine. These observations are also consistent with a limited role of transcriptional or translational regulation of CDO in response to diet.