Alternative processing of androgen-binding protein RNA transcripts in fetal rat liver. Identification of a transcript formed by trans splicing.
Alternative processing of androgen-binding protein RNA transcripts in fetal rat liver. Identification of a transcript formed by trans splicing.
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DOI：
10.1016/s0021-9258(18)52414-5
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发表时间：
1991-01
期刊：
影响因子：
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通讯作者：
Patrick Sullivan;Peter Petrusz;C. Szpirer;David R. Joseph
中科院分区：
文献类型：
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作者：
Patrick Sullivan;Peter Petrusz;C. Szpirer;David R. Joseph
雄激素及其核受体调节雄性表型发育所需的基因，这一过程被认为是由细胞外雄激素载体蛋白调节的。其中两种载体蛋白，睾丸雄激素结合蛋白（ABP）和血浆性激素结合球蛋白（SHBG），由同一基因编码，但糖基化和可能的氨基酸序列不同。为了研究胎鼠肝脏中 ABP-SHBG 基因的表达，我们分析了 RNA 转录本和表达的蛋白质。这些研究表明，在沃尔夫管依赖睾酮的分化过程中，ABP 在肝细胞中短暂表达。对源自胎鼠肝脏 cDNA 文库的 cDNA 克隆进行分析，鉴定出由 ABP-SHBG 基因编码的两个 cDNA，它们代表选择性剪接的 RNA。一个 cDNA 有一个替代外显子 1，表明胎儿肝脏中另一个启动子的功能。该 cDNA 还缺乏睾丸外显子 6 DNA，这一改变表明编码的蛋白质具有调节功能。另一个 cDNA 代表 ABP-SHBG 基因（外显子 1-5）和组氨酸脱羧酶 (HDC) 基因的融合转录本，编码 Mr 98,000 前体蛋白。这两个结构域在 ABP-SHBG 和 HDC 基因的剪接处连接，分别位于大鼠 10 号和 3 号染色体上。我们的结果表明，两个结构域的连接是通过反式（供体和受体）剪接机制实现的。 Northern 杂交实验的数据表明融合转录本存在于胎儿肝脏 RNA 中。使用胎儿肝脏 cDNA 进行的聚合酶链反应实验进一步支持 ABP-HDC 融合转录本以及其他替代 mRNA 的存在。此外，在ABP和HDC基因表达期间，Mr 93,000免疫反应蛋白在胎儿肝脏中短暂表达。融合 cDNA 在 COS 细胞中的表达产生了 HDC 活性，并在蛋白质免疫印迹上产生了预测大小的蛋白质 (Mr = 93,000)。
Androgens and their nuclear receptor regulate genes necessary for development of the male phenotype, a process that is thought to be modulated by extracellular androgen carrier proteins. Two of these carrier proteins, testicular androgen-binding protein (ABP) and plasma sex hormone-binding globulin (SHBG), are encoded by the same gene, but differ in glycosylation and possibly amino acid sequence. To investigate ABP-SHBG gene expression in fetal rat liver, we analyzed RNA transcripts and expressed protein. These studies demonstrated a transient expression of ABP in hepatocytes during the time of testosterone-dependent differentiation of the Wolffian duct. Analysis of cDNA clones derived from fetal rat liver cDNA libraries identified two cDNAs encoded by the ABP-SHBG gene that represented alternatively spliced RNAs. One cDNA had an alternate exon 1, suggesting the function of another promoter in fetal liver. This cDNA also lacked testicular exon 6 DNA, an alteration that implicates the encoded protein in regulatory functions. The other cDNA represented a fused transcript of the ABP-SHBG gene (exons 1-5) and the histidine decarboxylase (HDC) gene, encoding a Mr 98,000 precursor protein. The two domains were joined at splice junctions of the ABP-SHBG and HDC genes, which were localized to rat chromosomes 10 and 3, respectively. Our results indicate that the joining of the two domains was by a trans (donor and acceptor)-splicing mechanism. Data from Northern hybridization experiments suggest the fusion transcript is present in fetal liver RNA. Polymerase chain reaction experiments with fetal liver cDNA further support the existence of an ABP-HDC fusion transcript, as well as the other alternate mRNA. Moreover, a Mr 93,000 immunoreactive protein was transiently expressed in fetal liver during the time of ABP and HDC gene expression. Expression of the fusion cDNA in COS cells yielded HDC activity and the predicted size protein (Mr = 93,000) on Western immunoblots.