RETINOIC ACID SPECIFICALLY INCREASES NUCLEAR PKC-ALPHA AND STIMULATES AP-1 TRANSCRIPTIONAL ACTIVITY IN B16 MOUSE MELANOMA-CELLS
RETINOIC ACID SPECIFICALLY INCREASES NUCLEAR PKC-ALPHA AND STIMULATES AP-1 TRANSCRIPTIONAL ACTIVITY IN B16 MOUSE MELANOMA-CELLS
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DOI：
10.1006/excr.1995.1388
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发表时间：
1995-12-01
影响因子：
3.7
通讯作者：
NILES, RM
中科院分区：
文献类型：
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作者：
GRUBER, JR;DESAI, S;NILES, RM
B16 黑色素瘤细胞在用视黄酸 (RA) 处理后会分化，这种分化过程伴随着蛋白激酶 C α (PKC α) mRNA 和蛋白质水平的增加，这些细胞中 PKC α 的过度表达会导致更加分化的表型，表明该蛋白质在 Rk 控制分化中的重要性。本文报道的研究目的是确定 RA 诱导的 PKC α 的亚细胞分布，无论 RA 诱导的 PKC α 的亚细胞分布是否增加， PKC α 蛋白水平伴随着原位酶活性的增加，以及 RA 是否改变 AP-I 转录活性，我们发现 RA 处理增加了所有检查的亚细胞区室中的 PKC α 蛋白水平，但它也诱导了核相关 PKC α 水平的选择性富集，用活性佛波酯处理细胞诱导 PKC α 易位到膜部分，但对核 PKC α 水平没有影响，RA 还增加了 PKC通过 PKC 特异性内源底物 MARCKS 的磷酸化确定完整细胞中的酶活性。然而，虽然 RA 诱导总细胞 PKC α 蛋白水平增加 5 至 8 倍，但它仅使 MARCKS 磷酸化增加两倍。鉴于原位 PMC 酶活性的增加和核 PKC α 的富集，我们确定了 RA 处理的细胞中 AP-1 活性是否可能增加。使用转染到 B16 细胞中的带有或不带有 AP-1 元件的荧光素酶报告基因构建体表明 RA 诱导 AP-1 转录活性增加四到五倍。这些结果提出了一个假设，即 RA 诱导的核 PKC α 可能导致 AP-1 活性增加，并表明 RA 诱导的生长抑制和分化并不总是伴随着 AP-1 活性的抑制，正如其他研究人员提出的那样。 (C) 1995 学术出版社
B16 melanoma cells differentiate upon treatment with retinoic acid (RA), This differentiation process is accompanied by an increase of protein kinase C alpha (PKC alpha) mRNA and protein levels, Overexpression of PKC alpha in these cells results in a more differentiated phenotype, suggesting the importance of this protein in the control of differentiation by Rk The purpose of the study reported here was to determine the subcellular distribution of the RA-induced PKC alpha, whether the RA-induced increase in PKC alpha protein levels was accompanied by an increase in in situ enzyme activity, and whether RA altered AP-I transcriptional activity, We found that RA treatment increased PKC alpha protein levels in all subcellular compartments examined, but it also induced a selective enrichment in nuclear-associated PKC alpha levels, Treating cells with an active phorbol ester induced translocation of PKC alpha to membrane fractions, but had no effect on nuclear PKC alpha levels, RA also increased PKC enzymatic activity in intact cells as determined by phosphorylation of the PKC-specific endogenous substrate MARCKS, However, while RA induced a five- to eightfold increase in total cellular PKC alpha protein levels, it only increased MARCKS phosphorylation by twofold. In light of the increase in in situ PMC enzyme activity and the enrichment of nuclear PKC alpha, We determined whether AP-1 activity might be increased in RA-treated cells. Use of luciferase reporter gene constructs with or without AP-1 elements transfected into B16 cells indicated that RA induced a four- to fivefold increase in AP-1 transcriptional activity, These results suggest a hypothesis whereby RA-induced nuclear PKC alpha might lead to increased AP-1 activity and show that RA-induced growth inhibition and differentiation are not always accompanied by an inhibition of AP-1 activity as has been proposed by other investigators. (C) 1995 Academic Press, Inc.