Analysis of the mutant mice for transcription factor Mitf, which exhibit abnormalities of respiratory control and circadian rhythm

黑素细胞分化需要转录因子MITF、Sox10、分泌蛋白Endothelin 3及其受体Endothelin Receptor type B(EDNRB)。这些突变的小鼠由于缺乏黑色素细胞而表现出白色的毛色。为了寻找黑色素细胞的新的生理作用，我们对MITF突变小鼠，黑眼白色MITF^&lt；mi-BW&gt；(BW)进行了生理分析。因此我们发现BW小鼠与野生型小鼠相比，在夜间表现出更多的自发行为。我们进一步检测了BW小鼠的呼吸反应，如呼吸频率，潮气量，以及未麻醉和不受束缚的小鼠的分钟通气量。BW小鼠对低氧(10%O_2)或高二氧化碳(10%CO_2)的呼吸反应增强。这些意想不到的发现提示BW小鼠存在昼夜节律和呼吸调节的异常。为了阐明BW小鼠的病理，我们比较了…基因的表达谱通过基因芯片分析野生型和纯合子BW小鼠皮肤的差异，确定Lipocalin型前列腺素D合成酶(Lipocalin型前列腺素D合成酶，Lipocalin型前列腺素D合成酶)是一个新的黑素细胞标志物，负责前列腺素D2的产生。MITF激活了小鼠L-PGDS基因的转录，可能通过调节黑素细胞中前列腺素D_2的产生来维持皮肤的动态平衡。我们还为Sox10调控人黑素细胞系细胞中EDNRB基因的表达提供了证据。此外，我们还发现，EDNRB启动子在HeLa人宫颈癌细胞中高度甲基化，缺乏EDNRB表达，但在黑素细胞系细胞中不表达。经去甲基化试剂5‘-氮杂-2’-脱氧胞苷处理后，HeLa细胞中可检测到EDNRB的表达，在高表达Sox10的转化细胞中，EDNRB的表达进一步增强。这些结果表明，Sox10调控EDNRB基因的转录，从而确保EDNRB在人黑素细胞中的适当表达水平。较少

Differentiation of melanocytes is required for transcription factors MITF, SOX10, secretory protein Endothelin 3 and its receptor, Endothelin receptor type B (EDNRB). These mutant mice exhibit white coat color due to the lack of melanocytes.To search new physiological roles of melanocytes, we performed physiological analyses of the mitf mutant mouse, black-eyed white Mitf^<mi-bw> (bw). We thus found that bw mouse shows the increase of spontaneous behavior during the night compared with wild-type mouse. We further examined the breathing response of bw mouse, such as breathing frequency, tidal volume, and minute ventilation in unanesthetized and unrestrained mice by whole body plethysmography. The bw mouse exhibited the enhanced ventilatory responses to either hypoxia (10% O_2) or hypercapnia (10% CO_2). These unexpected findings suggest the abnormalities of circadian rhythm and respiratory regulation in bw mouse.To clarify the pathology of bw mouse, we compared mRNA expression profiles … More between wild type and homozygous bw mouse skin by cDNA microarray analysis, and identified lipocalin-type prostaglandin D synthase (L-PGDS) as a new melanocyte marker, which is responsible for prostaglandin D_2 production. MITF activates the transcription of the mouse L-PGDS gene, and may modulate the production of prostaglandin D_2 in melanocytes for the homeostasis in the skin.We also provide evidence that SOX10 regulates the expression of EDNRB gene in human melanocyte-lineage cells. Furthermore, we have shown that the EDNRB promoter is heavily methylated in HeLa human cervical cancer cells, lacking EDNRB expression, but not in melanocyte-lineage cells. The expression of EDNRB became detectable in HeLa cells after treatment with a demethylating reagent, 5'-aza-2'-deoxycytidine, which was further enhanced in the transformed cells over-expressing SOX10. These results suggest that SOX10 regulates transcription of the EDNRB gene, thereby ensuring appropriate expression level of EDNRB in human melanocytes. Less