Functional characterization and receptor binding studies of the malic enzyme thyroid hormone response element.
Functional characterization and receptor binding studies of the malic enzyme thyroid hormone response element.
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苹果酸酶甲状腺激素反应元件的功能表征和受体结合研究。
DOI：
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发表时间：
1991
影响因子：
4.8
通讯作者：
V. Nikodem
中科院分区：
文献类型：
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作者：
Béatrice Desvergne;K. Petty;V. Nikodem
我们先前表明，苹果酸酶（ME）基因的5 ′侧翼区含有顺式调节元件（-281至-261），其结合甲状腺激素受体并赋予三碘甲腺原氨酸（T3）对ME启动子的转录诱导（Petty，K. J.，Desvergne，B.，Mitsuhashi，T.，和Nikodem，V.M.（1990）J.Biol.Chem.265，7395-7400）。在这份报告中，我们已经使用的ME甲状腺激素反应元件（TRE）的缺失和突变分析，以评估T3结合和反式激活TRE的几个亚区的作用。ME TRE被证明作为增强子赋予T3对异源启动子胸苷激酶的响应性。虽然T3处理诱导的启动子活性，激素的情况下，导致抑制，如通过氯霉素乙酰转移酶的表达水平在NIH 3 T3瞬时表达系统中的过表达的受体的存在下测量。阻遏的程度类似于相同的TRE突变体观察到的T3诱导的程度。突变和缺失分析表明，功能TRE是由不连续的离散区域组成，具有G残基簇和AGGACA序列的主导作用。这两种功能，诱导和抑制转录，与受体结合的ME TRE确定的竞争结合试验，使用野生型和突变的TRE作为竞争对手。
We previously showed that the 5'-flanking region of the malic enzyme (ME) gene contains a cis-regulatory element (-281 to -261) that binds thyroid hormone receptors and confers triiodothyronine (T3) inducibility of transcription to the ME promoter (Petty, K.J., Desvergne, B., Mitsuhashi, T., and Nikodem, V. M. (1990) J. Biol. Chem. 265, 7395-7400). In this report, we have used deletion and mutation analyses of the ME thyroid hormone response element (TRE) to evaluate the roles of several subregions of TRE in T3 binding and transactivation. ME TRE was shown to act as an enhancer conferring T3 responsiveness to a heterologous promoter thymidine kinase. Although T3 treatment induced the promoter activity, the absence of hormone resulted in repression as measured by the level of chloramphenicol acetyltransferase expression in the NIH 3T3 transient expression system in the presence of overexpressed receptor. The degree of repression was similar to the degree of T3 induction observed for the same TRE mutants. Mutation and deletion analyses indicated that the functional TRE is comprised of discrete regions that are not contiguous, with a dominant role of a cluster of G residues and an AGGACA sequence. Both functions, induction and repression of transcription, correlated with receptor binding to the ME TRE as determined by competition binding assays using wild type and mutated TRE as competitors.