Molecular cloning and characterization of human cardiac homeobox gene CSX1.
Molecular cloning and characterization of human cardiac homeobox gene CSX1.
复制标题
人心脏同源盒基因CSX1的分子克隆和表征。
作者：
I. Shiojima;I. Komuro;T. Mizuno;R. Aikawa;H. Akazawa;T. Oka;T. Yamazaki;Y. Yazaki
越来越多的证据表明，含有同源结构域的蛋白质在调节组织特异性基因表达方面发挥着关键作用，这些基因表达对于组织分化至关重要，并决定了发育的时间和空间模式。为了阐明人类心脏发育的机制，我们分离了小鼠心脏同源框基因CSX(也称为NKX-2.5)的一个人类同源基因，并将其命名为CSX1。CSX1同源域的氨基酸序列与小鼠CSX/NKX-2.5和果蝇Tinman的氨基酸序列同源性分别为100%和67%。CSX1至少有三种由另一种剪接机制产生的异构体。其中一个亚型(CSX1a)编码一个约35kD的蛋白，具有同源结构域，而另外两个亚型(CSX1b和CSX1c)编码一个约12kD的截短蛋白，其氨基端112个氨基酸与CSX1a蛋白相同，但缺乏同源结构域。Northern印迹分析表明，CSX1转录本在胎儿和成人心脏中都有大量表达，但在被检测的其他人体组织中没有检测到信号。逆转录聚合酶链式反应对各亚型的扩增结果表明，三种亚型均在胎儿和成人心脏中表达，其中同源异构体CSX1a含量最高。CSX1a编码的同源结构域蛋白与CSX/Nkx-2.5结合序列结合，反式激活含序列的荧光素酶报告基因。出乎意料的是，CSX1b编码的缺乏同源结构域的蛋白也反式激活了报告基因，尽管CSX1b不与CSX/Nkx-2.5结合序列结合。在进化过程中高度保守的同源结构域序列和在心脏中的限制性表达表明CSX1在人类心脏的发育和分化中发挥着重要作用，CSX1蛋白在转录调控中可能存在两种不同的机制，即同源结构域依赖和非依赖机制。
Accumulating evidence has suggested that homeo-domain-containing proteins play critical roles in regulating the tissue-specific gene expression essential for tissue differentiation and in determining the temporal and spatial patterns of development. In order to elucidate the mechanisms of human heart development, we have isolated a human homologue of the murine cardiac homeobox gene Csx (also called Nkx-2.5) and denoted it as CSX1. The amino acid sequence of the CSX1 homeodomain is 100% and 67% identical to that of murine Csx/Nkx-2.5 and Drosophila tinman, respectively. CSX1 has at least three isoforms generated by an alternative splicing mechanism. One of these isoforms (CSX1a) encodes a protein of approximately 35 kD that possesses the homeodomain, whereas the other two (CSX1b and CSX1c) encode a truncated protein of approximately 12 kD that is identical to the CSX1a protein at the amino-terminal 112 amino acids but lacks the homeodomain. Northern blot analysis showed that CSX1 transcripts are abundantly expressed in both fetal and adult hearts, but no signal was detected in other human tissues examined. Amplification of each isoform by reverse transcriptase-polymerase chain reaction revealed that all of the three isoforms are expressed in fetal and adult hearts and that the homeobox-containing isoform CSX1a is most abundant. The homeodomain-containing protein encoded by CSX1a binds to Csx/Nkx-2.5 binding sequences and transactivates the sequence-containing luciferase reporter gene. Unexpectedly, the homeodomain-lacking protein encoded by CSX1b also transactivates the reporter gene, although CSX1b does not bind to the Csx/Nkx-2.5 binding sequences. The highly conserved homeodomain sequence in evolution and the restricted expression in the heart suggest that CSX1 plays an important role in the development and differentiation of the human heart and that there may be two different mechanisms in transcriptional regulation by the CSX1 protein, homeodomain-dependent and -independent mechanisms.
Tinman 是心脏和内脏中胚层规范所需的果蝇同源盒基因，可能由脊椎动物中的一个基因家族代表：XNkx-2.3，Tinman 的第二个脊椎动物同源物。
DOI：
10.1242/dev.121.11.3889
发表时间：
1995
期刊：
Development (Cambridge, England)
影响因子：
--
作者：
Evans,SM;Yan,W;Murillo,MP;Ponce,J;Papalopulu,N
通讯作者：
Papalopulu,N
影响因子：
10.5
作者：
LYONS, I;PARSONS, LM;HARVEY, RP
通讯作者：
HARVEY, RP
影响因子：
56.9
作者：
CASTRILLO, JL;THEILL, LE;KARIN, M
通讯作者：
KARIN, M