MECHANISMS OF MG2+ TRANSPORT IN SUBLINGUAL ACINAR CELLS

研究表明，镁离子缺乏是一个重要的致病因素 在许多疾病和紊乱中，可能包括唾液腺 功能障碍。很大一部分美国人口，多达75%， 可能面临潜在的镁离子缺乏。在许多情况下，镁离子扮演着关键的角色 细胞功能，例如，镁与三磷酸腺苷形成复合底物， 柠檬酸等；镁离子是激酶、磷酸酶和 合成酶；镁离子稳定膜和核糖体的结构 在蛋白质合成过程中；而镁离子调节离子通道，交换器， 共转运体和泵的活动。我们发现，镁离子能有效地 调节细胞内Na+浓度，影响细胞内Na+浓度 大鼠舌下腺泡细胞的pH。由于细胞内pH和Na+水平 对调节体液分泌过程非常重要，镁离子可能 在外分泌分泌功能的调节中起重要作用 唾液腺。然而，细胞内镁离子稳态的调节是 人们对此仍知之甚少。在初步研究中，我们发现在老鼠身上 舌下腺泡细胞，细胞内游离镁离子浓度为 受质膜中的镁离子转运系统和 胞内镁离子池。从胞内池中动员镁离子 可能依赖于钙离子，尽管镁离子转运的潜在机制 在质膜和胞内池中的情况尚不清楚。因此， 本项目的目的是探索镁离子的吸收和外流。 质膜和细胞内池中的通路。1)我们会 质膜中镁离子转运途径的研究 镁离子敏感荧光指示剂MAG-Fura-2监测镁离子内流 并在分离的舌下腺泡或单个细胞中挤出，并使用 阳离子通道阻滞剂、激活剂和离子交换抑制剂 描述镁离子流入和流出的途径。此外，我们还将申请 蛋白激酶C的激活物和抑制物及其调控 细胞内cAMP水平阐明镁离子的调节机制 助熔剂。2)我们将探索镁离子的吸收和释放机制。 细胞内的镁离子池，特别是钙离子在镁离子中的作用 有动静。在这个项目中，我们将阐明钙离子在镁离子中的作用 调控细胞内游离钙离子的摄取与释放 集中精神。这些研究的结果将为 镁离子和In对唾液分泌的调节机制 防治与镁离子相关的唾液腺功能障碍 缺乏症。

Studies indicate that Mg2+ deficiency is an important etiological factor in many diseases and disorders, possibly including salivary gland dysfunction. A large proportion of the U.S. population, as many as 75%, may face a latent Mg2+ deficiency. Mg2+ plays a critical role in many cell functions, for example, Mg2+ forms complex substrates with ATP, citrate, etc.; Mg2+ is a co-factor for kinases, phosphatases, and synthetases; Mg2+ stabilizes the structure of membranes and ribosomes during protein synthesis; and Mg2+ regulates ion channel, exchanger, cotransporter, and pump activities. We found that Mg2+ effectively regulates the intracellular Na+ concentration and affects intracellular pH in rat sublingual acinar cells. Since intracellular pH and Na+ level are very important for regulating the fluid secretion process, Mg2+ may play a vital role in the modulation of the secretory function of exocrine salivary glands. However,the regulation of cell Mg2+ homeostasis is still poorly understood. In preliminary studies, we found that in rat sublingual acinar cells, the intracellular free Mg2+ concentration is regulated by the Mg2+ transport systems in the plasma membrane and by an intracellular Mg2+ pool. Mg2+ mobilization from the intracellular pool may depend on Ca2+, although the underlying mechanisms of Mg2+ transport in the plasma membrane and intracellular pool are still unknown. thus, the purpose of this project is to explore the Mg2+ uptake and efflux pathways in the plasma membrane and intracellular pool. 1) we will characterize the Mg2+ transport pathways in the plasma membrane using Mg2+-sensitive fluorescent indicator, mag-fura-2, to monitor Mg2+ influx and extrusion in isolated sublingual acini or single cells, and using cation channel blockers, activators, and ion exchange inhibitors to characterize the Mg2_ influx and efflux pathways. Also, we will apply the activators and inhibitors of protein kinase C and manipulate intracellular cAMP levels to clarify the regulatory mechanism of Mg2+ fluxes. 2) we will explore the mechanisms of Mg2+ uptake and release in the intracellular Mg2+ pool, in particular the role of Ca2+ in Mg2+ movement. In this project, we will clarify the role of Ca2+ in Mg2+ uptake and release by manipulating the intracellular free Ca2+ concentration. The results from these studies will provide insight for elucidating the regulatory mechanism of saliva secretion by Mg2+ and in preventing and treating salivary gland dysfunctions associated with Mg2+ deficiency.