Dynamic regulation of the human dopachrome tautomerase promoter by MITF, ER-alpha and chromatin remodelers during proliferation and senescence of human melanocytes.
Dynamic regulation of the human dopachrome tautomerase promoter by MITF, ER-alpha and chromatin remodelers during proliferation and senescence of human melanocytes.
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在人黑素细胞增殖和衰老过程中，MITF、ER-α 和染色质重塑剂对人多巴色素互变异构酶启动子的动态调节。
DOI：
10.1111/j.1600-0749.2005.00229.x
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
Medrano,EstelaE
中科院分区：
文献类型：
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作者：
Schwahn,DeniseJ;Timchenko,NikolaiA;Shibahara,Shigeki;Medrano,EstelaE
已知衰老细胞表现出分化相关基因的基因表达改变。我们之前已经证明，黑素细胞转录调控蛋白小眼球相关蛋白(MITF)在衰老的黑素细胞中下调。由于对衰老黑素细胞的分化功能几乎一无所知，我们分析了酪氨酸酶基因家族成员多巴色素互变酶(DCT)在黑素细胞增殖和衰老中的转录调控。对含有MITF CATGTG结合基序的M-box区域的计算分析表明，该序列与雌激素受体α(ER-α)、USF-1、TFE-3、ISL-1和AP-1结合元件重叠。使用含有MITF和ERE元件的寡核苷酸的凝胶位移分析在增殖的黑素细胞中检测到MITF和ER-α复合体，而在衰老的细胞中仅检测到ER-α复合体。重要的是，启动子-报告基因分析表明，共激活子p300/CBP将MITF从抑制子转换为DCT转录激活子。ER-α和MITF还需要P300/CBP来诱导DCT启动子的高度协同激活。我们还发现，DCT基因的转录受主要黑素细胞有丝分裂原的差异调控。与cAMP诱导剂的激活作用不同，12-O-十四酰基膦乙酸酯(TPA)是DCT转录的有效抑制因子，这表明该基因可以受到多种环境信号和启动子上下文的差异调控。为了支持这一结论，组蛋白去乙酰酶抑制剂曲古抑素A抵消了TPA介导的抑制作用，并恢复了培养的黑素细胞中高水平的DCT蛋白。我们的结论是，衰老的黑素细胞在分化相关蛋白的表达上发生了戏剧性的变化；这种变化可能反过来导致黑素细胞功能的改变和对环境压力的存活。
Senescent cells are known to display altered gene expression of differentiation‐associated genes. We have previously demonstrated that the melanocyte transcriptional regulator microphthalmia‐associated protein (MITF) is down‐regulated in senescent melanocytes. Since virtually nothing is known regarding the differentiated function of senescent melanocytes, we analyzed the transcriptional regulation ofDopachrome tautomerase(DCT), a member of the tyrosinase gene family, in proliferating and in senescent human melanocytes. Computational analysis of the region containing the M‐box that includes the MITF CATGTG binding motif demonstrated that this sequence overlaps with the estrogen receptor alpha (ER‐α), USF‐1, TFE‐3, Isl‐1 and AP‐1 binding elements. Electrophoresis gel‐shift analysis using an oligonucleotide containing MITF and ERE elements identified MITF and ER‐αcomplexes in proliferating melanocytes, whereas only ER‐αcomplexes were detected in senescent cells. Importantly, a promoter‐reporter analysis demonstrated that the coactivator p300/CBP switched MITF from a repressor to an activator ofDCTtranscription. p300/CBP was also required by ER‐αand MITF to induce high, synergistic activation of theDCTpromoter. We have also found that transcription of theDCTgene is differentially regulated by major melanocyte mitogens. In contrast to the activating effect of cAMP inducers, 12‐O‐tetradecanoylphorbolacetate (TPA) was a potent repressor ofDCTtranscription, suggesting that this gene can be differentially regulated by multiple environmental signals and promoter context. In support of this conclusion, trichostatin A, a histone deacetylase inhibitor, counteracted the TPA‐mediated repression, and restored high levels of DCT protein in cultured melanocytes. We conclude that senescent melanocytes display dramatic changes in the expression of differentiation‐related proteins; such changes may in turn result in altered melanocyte function and survival to environmental stresses.