Regulation of expression of two different transcripts of the NF-1 gene in neuroblastoma
Regulation of expression of two different transcripts of the NF-1 gene in neuroblastoma
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DOI：
10.1023/a:1005789516322
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发表时间：
1997-01-01
影响因子：
3.9
通讯作者：
Schweizer, P
中科院分区：
文献类型：
--
作者：
Girgert, R;Schweizer, P
神经纤维蛋白是核因子-1基因的基因产物，以两种亚型表达。核因子-1II型m-RNA在所谓的GAP相关结构域插入了63个碱基，这使其有别于I型转录本。根据序列同源性，推测神经纤维素在细胞内信号转导中调节ras活性的功能与GTP酶激活蛋白(GAP)相似。在神经母细胞瘤中，两种转录产物以不同的摩尔比例同时表达。1)我们检测了9个不同的神经母细胞瘤细胞株中，第一型和第二型的表达比例。为了定量这两种转录产物，我们用设计的覆盖GAP相关结构域的引物，对神经母细胞瘤细胞的m-RNA进行了RT-PCR。我们发现从Kelly细胞系中I型转录本的3倍以上到IMR 5.2中II型转录本的轻微过剩(I/II=0.6)不等，因为有迹象表明，NF-1 II型的表达与分化状态有关，我们试图通过用维甲酸处理神经母细胞瘤细胞，将核因子-1的表达从I型转变为II型。用5mU维甲酸处理Kelly细胞24小时，已经将I型转录过量降低到仅1.6倍。通过将摩尔比从过量的I型转录逆转为过量的II型转录，可以研究这两种转录本在调节ras活性和分化中的不同作用。
Neurofibromin, the gene product of the NF-1 gene is expressed in two isoforms. The m-RNA of NF-1 type II contains an insertion of 63 bases in the so called GAP-related domain, that distinguishes it from the type I transcript. By sequence homology neurofibromin is supposed to have a similar function in regulating activity of ras in intracellular signal transduction as the GTPase activating protein (GAP). Both transcripts of NF-1 are simultaneously expressed in different molar ratio in neuroblastoma tumors.1) We examined 9 different neuroblastoma cell lines for the ratio of expression of NF-1 type I and type II. For quantification of the two transcripts we performed RT-PCR of the m-RNA of the neuroblastoma cells using primers designed to cover the GAP-related domain. We found values ranging from a more than 3-fold excess of type I transcript in the cell line Kelly to a slight excess of the type II transcript (I/II = 0.6) in the cell line IMR 5.2) As there are indications that expression of NF-1 type II is related to the state of differentiation, we tried to shift expression of NF-1 from type I to type II by treatment of the neuroblastoma cells with retinoic acid.Treatment of Kelly cells with 5 mu M retinoic acid for 24 h already lowered the excess of the type I transcript from 3-fold to an only 1.6-fold excess.An inversion of the molar ratio from an excess of the type I transcript to an excess of type II transcript would enable to investigate the different role of the two transcripts in the regulation of ras-activity and differentiation.