Mori K, Tanaka I, Kotani M, Miyaoka F, Sando T, Muro S, Sasaki Y, Nakagawa O, Ogawa Y, Usui T, Ozaki S, Ichikawa A, Narumiya S, Nakao K
Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, Japan.
J Mol Med (Berl). 1996 Jun;74(6):333-6. doi: 10.1007/BF00207510.
We isolated a cDNA clone encoding the human prostaglandin (PG) E receptor EP4 subtype and examined the gene expression in human blood cells. Northern blot analysis revealed that the EP4 gene is expressed at a high level in peripheral blood mononuclear cells, and at lower levels in cultured human blood cell lines, THP-1 and U937 (monocytoid cell lines), MOLT-4 and Jurkat (T-cell lines), and Raji (B-cell line). To examine regulation of the EP4 gene expression in the immune system, we studied the effects of phorbol 12-myristate 13-acetate (PMA) on these cell lines. Gene expression was upregulated in THP-1, U937, and Raji cells by PMA, and was downregulated in MOLT-4 and Jurkat cells. In THP-1 cells the effects of PMA were further analyzed, and the upregulation of the EP4 gene was shown to be followed by an increase in PGE2 binding sites and in PGE2-induced cAMP accumulation. In the striking contrast, other PGE receptor subtypes (EP1, EP2 and EP3) and other prostanoid receptors (IP and DP) were shown not to be upregulated by PMA. Therefore, this is the first demonstration of a highly specific upregulation of the EP4 subtype in THP-1 cells treated with PMA, suggesting the importance of the EP4 subtype in the immune system. In the present study we also clarified that EP4 gene expression is regulated differently among human monocytoid and lymphoid lineage cells, thus leading to the better understanding of the regulatory mechanisms for the human EP4 gene expression in the immune system.
我们分离出了一个编码人前列腺素（PG）E受体EP4亚型的cDNA克隆，并检测了其在人血细胞中的基因表达。Northern印迹分析显示，EP4基因在外周血单核细胞中高表达，而在培养的人血细胞系中表达水平较低，这些细胞系包括THP-1和U937（单核细胞样细胞系）、MOLT-4和Jurkat（T细胞系）以及Raji（B细胞系）。为了研究免疫系统中EP4基因表达的调控，我们研究了佛波酯12-肉豆蔻酸酯13-乙酸酯（PMA）对这些细胞系的影响。PMA使THP-1、U937和Raji细胞中的基因表达上调，而使MOLT-4和Jurkat细胞中的基因表达下调。在THP-1细胞中，我们进一步分析了PMA的作用，结果表明EP4基因的上调伴随着PGE2结合位点的增加以及PGE2诱导的cAMP积累的增加。与之形成鲜明对比的是，其他PGE受体亚型（EP1、EP2和EP3）以及其他类前列腺素受体（IP和DP）并未被PMA上调。因此，这是首次证明在经PMA处理的THP-1细胞中EP4亚型有高度特异性的上调，这表明EP4亚型在免疫系统中具有重要性。在本研究中，我们还阐明了EP4基因在人单核细胞样和淋巴细胞系细胞中的表达调控方式不同，从而有助于更好地理解免疫系统中人类EP4基因表达的调控机制。
