MOLECULAR BIOLOGY OF CARDIAC SODIUM CALCIUM EXCHANGE

心肌细胞的肌膜(质膜)具有高水平的 Na+-Ca2+交换活性。Na+-Ca2+交换是一种重要的机制 用于调节心肌钙离子，从而也调节心肌的收缩能力。 这个实验室最近克隆了Na+-Ca~(2+)交换器 开始对交换器进行分子分析。的长期目标是 这个项目是为了了解分布，调节和基因 交换器的结构。 针对这一目标，项目的具体目标如下：1. 亚型及其分布。代表该基因异构体的cDNA克隆 分离、测序和表达Na+-Ca~(2+)交换蛋白。异构体 将对功能和分布进行评估。2.监管。其影响 甲状腺激素、慢性洋地黄治疗和脑缺血 交换蛋白和RNA水平将被确定。这三个人 干预措施都会影响Na+-Ca~(2+)交换活性，建议的 实验将在分子水平上分析这些影响。3.基因 结构。转录调控元件与内含子/外显子 将对边界进行分析。上游监管的特征 这些元素将有助于理解不同基因的调控表达 交换基因产品。内含子/外显子图谱有助于理解 进化和蛋白质结构域关系。4.反义 寡核苷酸。具有反义mRNA序列的寡核苷酸 Na+-钙离子交换器将被引入细胞。这应该会阻止 交换蛋白的合成及其兴奋收缩反应 耦合路径将被分析。 Na~+-Ca~(2+)交换器是心肌收缩的重要调节因子。 对这种重要的心脏转运体的进一步分子知识将 帮助了解正常心脏和患病心脏的工作原理。

The sarcolemma (plasma membrane) of myocardial cells has high levels of Na+-Ca2+ exchange activity. Na+-Ca 2+ exchange is an important mechanism for regulating myocardial Ca 2+ and thereby also regulates contractility. This laboratory has recently cloned the Na+-Ca 2+ exchanger allowing molecular analysis of the exchanger to begin. The long-term objective of this project is to understand the distribution, regulation, and gene structure of the exchanger. Towards this goal, the specific aims of the project are as follows: 1. Isoforms and distribution. cDNA clones representing isoforms of the Na+-Ca2+ exchanger will be isolated, sequenced and expressed. Isoforms function and distribution will be assessed. 2. Regulation. The effects of thyroid hormone, chronic digitalis treatment, and ischemia on exchanger protein and RNA levels will be determined. These three interventions all affect Na+-Ca2+ exchange activity, and the proposed experiments will analyze these effects at the molecular level. 3. Gene structure. Transcriptional regulatory elements and intron/exon boundaries will be analyzed. Characterization of upstream regulatory elements will aid in understanding the regulated expression of different exchanger gene products. Intron/exon maps are useful in understanding evolutionary and protein domain relationships. 4. Antisense oligonucleotides. Oligonucleotides with sequences antisense to mRNA for the Na+-Ca2+ exchanger will be introduced into cells. This should block synthesis of exchanger protein and the response of excitation-contraction coupling pathways will be analyzed. The Na+-Ca 2+ exchanger is an important regulator of contractility. Further molecular knowledge of this essential cardiac transporter will aid in understanding the workings of both normal and diseased hearts.