Suppression of Melanin Production by Expression of HSP70
Suppression of Melanin Production by Expression of HSP70
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DOI：
10.1074/jbc.m110.103051
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发表时间：
2010-04-23
影响因子：
4.8
通讯作者：
Mizushima, Tohru
中科院分区：
文献类型：
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作者：
Hoshino, Tatsuya;Matsuda, Minoru;Mizushima, Tohru
由于紫外线（UV）照射引起的异常黑色素生成导致的皮肤色素沉着症是临床和美容问题。紫外线照射通过增加细胞内cAMP刺激黑素细胞中的黑色素产生。热休克蛋白（HSP），特别是HSP 70的表达由各种应激源（包括UV照射）诱导，以提供对这些应激源的细胞抗性。在这项研究中，我们研究了HSP 70的表达在体外和体内对黑色素生成的影响。3-异丁基-1-甲基黄嘌呤（IBMX），cAMP升高剂，刺激培养的小鼠黑色素瘤细胞中的黑色素生成，这种刺激在过表达HSP 70的细胞中被抑制。酪氨酸酶基因的IBMX依赖性转录激活在HSP 70过表达细胞中也被抑制。小眼症相关的转录因子（MITF），它积极调节酪氨酸酶基因的转录，表达上调IBMX，然而，这种上调在HSP 70过表达细胞中没有抑制。另一方面，免疫沉淀和免疫染色分析显示，MITF和HSP 70之间的物理相互作用和共定位，分别。此外，核提取物中酪氨酸酶基因的转录被HSP 70抑制。在体内，野生型小鼠的紫外线照射增加了表皮基底层中黑色素的量，并且这种增加在表达HSP 70的转基因小鼠中被抑制。这项研究提供了第一个证据表明，热休克蛋白70的抑制作用，在体外和体内黑色素的生产。这种作用似乎是通过HSP 70和MITF之间的直接相互作用来调节MITF活性。
Skin hyperpigmentation disorders due to abnormal melanin production induced by ultraviolet (UV) irradiation are both a clinical and cosmetic problem. UV irradiation stimulates melanin production in melanocytes by increasing intracellular cAMP. Expression of heat shock proteins (HSPs), especially HSP70, is induced by various stressors, including UV irradiation, to provide cellular resistance to such stressors. In this study we examined the effect of expression of HSP70 on melanin production both in vitro and in vivo. 3-Isobutyl-1-methylxanthine (IBMX), a cAMP-elevating agent, stimulated melanin production in cultured mouse melanoma cells, and this stimulation was suppressed in cells overexpressing HSP70. IBMX-dependent transcriptional activation of the tyrosinase gene was also suppressed in HSP70-overexpressing cells. Expression of microphthalmia-associated transcription factor (MITF), which positively regulates transcription of the tyrosinase gene, was up-regulated by IBMX; however, this up-regulation was not suppressed in HSP70-overexpressing cells. On the other hand, immunoprecipitation and immunostaining analyses revealed a physical interaction between and co-localization of MITF and HSP70, respectively. Furthermore, the transcription of tyrosinase gene in nuclear extract was inhibited by HSP70. In vivo, UV irradiation of wild-type mice increased the amount of melanin in the basal layer of the epidermis, and this increase was suppressed in transgenic mice expressing HSP70. This study provides the first evidence of an inhibitory effect of HSP70 on melanin production both in vitro and in vivo. This effect seems to be mediated by modulation of MITF activity through a direct interaction between HSP70 and MITF.