Magnesium Deficiency: Global Gene Expression Study

说明(申请人提供)：镁(镁)是细胞中第二丰富的阳离子。由于镁离子是数百种酶反应中的辅因子，它对DNA和蛋白质的合成、离子转运、细胞内信号转导以及细胞的生长和分化等许多生物学活动都有深远的影响。因此，镁离子缺乏与动脉粥样硬化、高血压、糖尿病、哮喘和酗酒等多种疾病状态有关也就不足为奇了。然而，我们对镁离子动态平衡的理解远远落后于其他阳离子，如钙离子、钠离子、钾离子和氢离子，这很大程度上是因为在分子水平上还没有确定镁离子的转运体。此外，关于镁缺乏对基因表达的影响，特别是关于其在各种病理条件下的作用的研究还很少。利用基因芯片进行基因表达谱分析是识别特定细胞或疾病过程中涉及的基因的一种强有力的方法。我们建议使用这项技术来识别与镁稳态有关的基因，并阐明镁缺乏导致各种疾病状态的机制。通过比较正常小鼠和缺镁小鼠选定器官的全球基因表达模式，应该有可能识别涉及镁稳态的基因，例如编码镁转运蛋白的基因。在缺镁条件下异常表达的基因也应该被识别出来。这应该会让人们更好地理解镁在健康和疾病中的作用。在AIMS 1和2中，商业基因芯片将分别用于研究急性和慢性镁缺乏对基因表达的影响。在AIM 3中，将从镁充足和缺镁小鼠的不同器官中构建抑制消减杂交库。然后，文库中的克隆将被用于构建定制的基因表达谱微阵列。这种技术的结合应该能够识别出在缺镁期间差异表达的所有基因。

DESCRIPTION (provided by applicant): Magnesium (Mg2+) is the second most abundant cation in cells. Because Mg2+ serves as a cofactor in hundreds of enzymatic reactions, it has a profound influence on many biological activities including DNA and protein synthesis, ion transport, intracellular signal transduction, and cell growth and differentiation. Consequently, it is not surprising that Mg2+ deficiency has been implicated in various disease states such as atherosclerosis, hypertension, diabetes, asthma, and alcoholism. Yet, our understanding of Mg2+ homeostasis lags far behind that of other cations such as Ca2+, Na+, K+, and H+, largely because the transporters of Mg2+ have not been identified at the molecular level. In addition, little work has been conducted concerning the effects of Mg2+ deficiency on gene expression, especially with respect to its role in various pathological conditions. Gene expression profiling using cDNA microarrays represents a powerful method for identifying genes involved in specific cellular or disease processes. We propose to use this technology to identify genes involved in magnesium homeostasis and to elucidate the mechanisms by which magnesium deficiency leads to various disease states. By comparing global gene expression patterns of select organs of normal mice to their counterparts in magnesium-deficient mice, it should be possible to identify genes involved in magnesium homeostasis, such as those encoding magnesium transporters. Genes that are aberrantly expressed under magnesium-deficient conditions should also be identified. This should lead to a better understanding of magnesium's role in health and disease. In Aims 1 and 2 commercial cDNA microarrays will be used to investigate the effects of acute and chronic magnesium deficiency on gene expression, respectively. In Aim 3 suppression subtraction hybridization libraries will be constructed from various organs of magnesium-replete and magnesium-deficient mice. Clones from the library will then be used to construct custom cDNA microarrays for gene expression profiling. This combination of techniques should lead to the identification of all genes that are differentially expressed during magnesium deficiency.