Barnes K V, Cheng G, Dawson M M, Menick D R
Cardiology Division, Department of Medicine and the Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina 29425-2221, USA.
J Biol Chem. 1997 Apr 25;272(17):11510-7.
The Na+-Ca2+ exchanger (NCX1) plays a major role in calcium efflux and therefore in the control and regulation of intracellular calcium in the heart. The exchanger has been shown to be regulated at several levels including transcription. NCX1 mRNA levels are up-regulated in both cardiac hypertrophy and failure. In this work, the 5'-end of the ncx1 gene has been cloned to study the mechanisms that mediate hypertrophic stimulation and cardiac expression. The feline ncx1 gene has three exons that encode 5'-untranslated sequences that are under the control of three tissue-specific promoters. The cardiac promoter drives expression in cardiocytes, but not in mouse L cells. Although it contains at least one enhancer (-2000 to -1250 base pairs (bp)) and one or more negative elements (-1250 to -250 bp), a minimum promoter (-250 to +200 bp) is sufficient for cardiac expression and alpha-adrenergic stimulation.
钠钙交换体（NCX1）在钙外流中起主要作用，因此在心脏细胞内钙的控制和调节中也起主要作用。已证明该交换体在包括转录在内的多个水平受到调控。在心肌肥大和心力衰竭中，NCX1 mRNA水平均上调。在本研究中，已克隆了ncx1基因的5′端，以研究介导肥大刺激和心脏表达的机制。猫的ncx1基因有三个外显子，它们编码5′非翻译序列，这些序列受三个组织特异性启动子的控制。心脏启动子驱动心肌细胞中的表达，但在小鼠L细胞中不驱动表达。尽管它包含至少一个增强子（-2000至-1250碱基对（bp））和一个或多个负调控元件（-1250至-250 bp），但最小启动子（-250至+20 bp）足以驱动心脏表达和α-肾上腺素能刺激。
