TAT PROTEIN OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 REPRESSES EXPRESSION OF MANGANESE SUPEROXIDE-DISMUTASE IN HELA-CELLS
TAT PROTEIN OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 REPRESSES EXPRESSION OF MANGANESE SUPEROXIDE-DISMUTASE IN HELA-CELLS
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DOI：
10.1073/pnas.90.16.7632
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发表时间：
1993-08-15
影响因子：
11.1
通讯作者：
MCCORD, JM
中科院分区：
文献类型：
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作者：
FLORES, SC;MARECKI, JC;MCCORD, JM
利用稳定转染人类免疫缺陷病毒1型tat基因的HeLa细胞系，我们发现调控tat蛋白的表达抑制细胞含锰超氧化物歧化酶（Mn-SOD）的表达。这种酶是细胞对氧自由基的主要防御之一，对维持氧化剂和抗氧化剂之间的健康平衡至关重要。亲本HeLa细胞表达了几乎等量的Cu、Zn和Mn-SOD同工酶。表达Tat蛋白的细胞的Mn-SOD活性比亲本细胞低52%，而表达Cu、Zn酶的细胞活性基本不变。在HeLa-tat细胞系中mn - sod特异性rna的稳态水平也低于亲本细胞系。Cu， zn - sod特异性rna的稳态水平没有差异。除了Mn-SOD活性降低外，HeLa-tat细胞还表现出氧化应激增加的迹象。细胞提取物中羰基蛋白明显升高，细胞总巯基含量以更快的速度下降，可能反映了持续的脂质过氧化。将HeLa和HeLa-tat提取物与放射性标记的Mn-SOD转录物孵育，反应产物进行紫外交联、核糖核酸酶A酶切和电泳分析。结果表明Tat蛋白与Mn-SOD基因转录物之间存在直接相互作用。
Using a HeLa cell line stably transfected with the tat gene from human immunodeficiency virus type 1, we have found that the expression of the regulatory Tat protein suppresses the expression of cellular Mn-containing superoxide dismutase (Mn-SOD). This enzyme is one of the cell's primary defenses against oxygen-derived free radicals and is vital for maintaining a healthy balance between oxidants and antioxidants. The parental HeLa cells expressed nearly equivalent amounts of Cu,Zn- and Mn-SOD isozymes. Those cells expressing the Tat protein, however, contained 52% less Mn-SOD activity than parental cells, whereas that of the Cu,Zn enzyme was essentially unchanged. The steady-state levels of Mn-SOD-specific RNAs were also lower in the HeLa-tat cell line than in the parental line. No difference was seen in the steady-state levels of Cu,Zn-SOD-specific RNAs. In addition to the decreased Mn-SOD activity, HeLa-tat cells showed evidence of increased oxidative stress. Carbonyl proteins were markedly higher, and total cellular sulfhydryl content decreased in cell extracts at a faster rate, probably reflecting ongoing lipid peroxidation. HeLa and HeLa-tat extracts were incubated with radiolabeled Mn-SOD transcripts, and the reaction products were subjected to UV crosslinking, digestion with ribonuclease A, and electrophoretic analysis. The results suggest a direct interaction between Tat protein and Mn-SOD gene transcripts.