Regulatory elements in the first intron of the rat fatty acid synthase gene.
Regulatory elements in the first intron of the rat fatty acid synthase gene.
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大鼠脂肪酸合酶基因第一个内含子中的调节元件。
DOI：
10.1042/bj3240113
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Smith,S
中科院分区：
文献类型：
--
作者：
Oskouian,B;Rangan,VS;Smith,S
在脂肪酸合成酶（FAS）基因的1.2kb长的第一内含子内已经鉴定出序列元件，其介导对转录的正效应和负效应。当位于FAS或猿猴病毒40启动子下游时，负调控元件以方向依赖性方式下调偶联的报告基因的表达。通过缺失诱变，介导这种效应的序列已经定位到大约在核苷酸+405至+768和+924至+1083内的两个区域。这两个区域都含有被从肝脏制备的核提取物强烈保护而不被从脾脏制备的核提取物消化的序列元件。用来自高或低水平表达FAS的组织的细胞核进行的连续测定的结果表明，内源性FAS基因的不同转录速率是由起始程度的差异引起的，因此不太可能由第一内含子中的转录暂停引起负面效应。阳性元件定位于nt +292至+297，对应于上游刺激因子（USF）的真实结合位点。这种USF结合元件可以以位置和方向独立的方式上调异源启动子的转录。然而，在整个FAS第一内含子的情况下，USF结合位点的作用被掩蔽，除非通过诱变消除负元件的作用。这些结果表明，第一内含子的显性负元件可能在决定FAS基因的组织特异性表达中发挥作用。
Sequence elements have been identified within the 1.2 kb-long first intron of the fatty acid synthase (FAS) gene that mediate both positive and negative effects on transcription. The negative regulatory element, when positioned downstream of either the FAS or simian virus 40 promoter, down-regulates the expression of a coupled reporter gene in an orientation-dependent manner. Sequences mediating this effect have been mapped, by deletion mutagenesis, to two regions approximately within nucleotides +405 to +768 and +924 to +1083. Both regions contain sequence elements that are strongly protected from DNase I digestion by nuclear extracts prepared from liver, but not by those prepared from spleen. The results of run-on assays performed with nuclei derived from tissues that express FAS at either high or low levels indicate that the different rates of transcription of the endogenous FAS gene result from differences in the extent of initiation, so it is unlikely that the negative effect is caused by transcriptional pausing in the first intron. The positive element maps to nt +292 to +297 and corresponds to an authentic binding site for upstream stimulatory factor (USF). This USF-binding element can up-regulate transcription from a heterologous promoter in a position- and orientation-independent manner. However, in the context of the entire FAS first intron, the effect of the USF-binding site is masked unless the effect of the negative elements is ablated by mutagenesis. These results suggest that the dominant negative element of the first intron may play a role in determining the tissue-specific expression of the FAS gene.