MELANOCYTE-SPECIFIC EXPRESSION OF THE HUMAN TYROSINASE PROMOTER - ACTIVATION BY THE MICROPHTHALMIA GENE-PRODUCT AND ROLE OF THE INITIATOR
MELANOCYTE-SPECIFIC EXPRESSION OF THE HUMAN TYROSINASE PROMOTER - ACTIVATION BY THE MICROPHTHALMIA GENE-PRODUCT AND ROLE OF THE INITIATOR
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DOI：
10.1128/mcb.14.12.7996
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发表时间：
1994-12-01
影响因子：
5.3
通讯作者：
GODING, CR
中科院分区：
文献类型：
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作者：
BENTLEY, NJ;EISEN, T;GODING, CR
酪氨酸酶基因在黑素细胞和视网膜色素上皮细胞中特异性表达，它们共同负责皮肤、头发和眼睛的颜色。通过使用DNA酶I足迹法和带移分析的组合加上特定的DNA元件的诱变，我们研究了黑素细胞特异性表达的人酪氨酸酶启动子的要求。我们发现，少至115 bp的上游序列足以指导组织特异性表达。这个115 bp的片段包含三个阳性元件：M盒，在其他黑素细胞特异性启动子中发现的保守元件; Sp1位点;以及位于-14和+1之间的高度进化保守元件，其包含E-box基序和重叠的八聚体元件。此外，另外两个元件，一个正的和一个负的，分别位于位置-185和-150以及位置-150和-115之间。我们还发现，由小眼症基因编码的基本螺旋-环-螺旋因子，这是黑素细胞分化所必需的，可以通过位于启动子附近的M盒和保守的E盒反式激活酪氨酸酶启动子。由于在体外试验未能确定任何黑素细胞特异性DNA结合活性，在基础酪氨酸酶启动子内的元素的具体安排决定黑素细胞特异性表达的可能性进行了讨论。
The tyrosinase gene is expressed specifically in melanocytes and the cells of the retinal pigment epithelium, which together are responsible for skin, hair, and eye color. By using a combination of DNase I footprinting and band shift assays coupled with mutagenesis of specific DNA elements, we examined the requirements for melanocyte-specific expression of the human tyrosinase promoter. We found that as little as 115 bp of the upstream sequence was sufficient to direct tissue-specific expression. This 115 bp stretch contains three positive elements: the M box, a conserved element found in other melanocyte-specific promoters; an Sp1 site; and a highly evolutionarily conserved element located between -14 and +1 comprising an E-box motif and an overlapping octamer element. In addition, two further elements, one positive and one negative, are located between positions -185 and -150 and positions -150 and -115, respectively. We also found that the basic helix-loop-helix factor encoded by the microphthalmia gene, which is essential for melanocyte differentiation, can transactivate the tyrosinase promoter via the M box and the conserved E box located close to the initiator. Since in vitro assays failed to identify any melanocyte-specific DNA-binding activity, the possibility that the specific arrangement of elements within the basal tyrosinase promoter determines melanocyte-specific expression is discussed.