CELLULAR AND SUBCELLULAR CALCIUM ION HOMEOSTASIS

这个项目的重点是细胞达到动态平衡的机制。 胞浆和其他细胞内的钙离子浓度 脑室，并允许改变钙离子对激素和 神经递质。我们目前关注的是精神错乱的角色 细胞死亡过程中的钙稳态。今年我们有 探讨BC12癌基因过表达对人肝癌细胞生长的影响 Jurkat T细胞对胞浆[Ca~(2+)]的调节作用 Thapsigargin敏感的内质网钙离子池。作为回应 在血清饥饿的情况下，BC12转基因细胞的存活时间更长， 维持一个更大的thapsigarin可释放的钙离子池 控制单元。两者之间可能存在因果关系 这两个参数。 我们还提出了这样一个问题，即通过暴露杀死细胞 在有卟啉存在的可见光下累及外周 线粒体膜上苯二氮卓类受体的开放 线粒体的“巨无霸”和随之而来的脉搏释放 钙离子进入胞浆。在对分离的线粒体的研究中 心脏和肝脏，暴露于卟啉和光线中被发现 非常有效地抑制线粒体钙摄取，并在 导致累积的钙离子释放。然而，效果并不是这样 被环孢菌素阻断，环孢菌素抑制巨噬细胞的打开， 并且确实涉及解偶联，如膜的荧光所示 电敏染料JC-1。因此，通过以下方式诱导损害 光动力疗法在机制上比开放这个 独播频道。这些关于细胞死亡中的钙离子的研究是针对 对这一过程的基本生物学的理解，并最终 设计干预措施以防止不必要的细胞死亡的目标 老化过程中固定的有丝分裂后组织。

This project focuses on the mechanism whereby cells achieve homeostasis of Ca2+ ion concentration, both within the cytosol and other cellular compartments, and allow changes in Ca2+ in response of hormones and neurotransmitters. We are currently focussing on the role of deranged Ca2+ homeostasis in the process of cell death. This year we have investigated the effect of the overexpression of the bc12 oncogene in the Jurkat T cell line upon regulation of cytosol [Ca2+] and the thapsigargin-sensitive pool of endoplasmic reticulum Ca2+. In response to serum-starvation, the bc12-transfected cells survive longer and maintain a larger thapsigargin-releasable pool of Ca2+ than do the control cells. There may be a cause-and-effect relationship between these two parameters. We have also asked the question of whether killing of cells by exposure to visible light in the presence of porphyrins involves the peripheral benzodiazepine receptor in the mitochondrial membrane, the opening of the mitochondrial "megachannel" and the consequent release of a pulse of Ca2+ into the cytosol. In studies with mitochondrial isolated from heart and liver, exposure to porphyrins and light was found to be extremely effective in inhibiting mitochondrial Ca2+ uptake and in causing release of accumulated Ca2+. However, the effect was not blocked by cyclosporin, which inhibits the opening of the megachannel, and did involve uncoupling, as shown by fluorescence of the membrane potential-sensitive dye JC-1. Thus, the induction of damage by photodynamic therapy is broader in mechanism than the opening of this channel alone. These studies on Ca2+ in cell death are geared towards an understanding of the basic biology of this process, with an eventual goal of designing interventions to prevent unwanted cell death in fixed, post-mitotic tissues during aging.