CELLULAR AND SUBCELLULAR CALCIUM ION HOMEOSTASIS

这个项目的重点是细胞实现稳态的机制 Ca2+离子浓度，无论是在胞质溶胶和其他细胞 隔室，并允许响应激素和钙离子的变化， 神经传递素 我们目前关注的是精神错乱的角色 细胞死亡过程中的Ca2+稳态。 今年我们有 研究了bc12癌基因过表达对 Jurkat T细胞系在调节细胞质[Ca 2 +]和 内质网Ca~（2+）的毒胡萝卜素敏感池。 响应 对血清饥饿，转染bc12的细胞存活时间更长， 维持一个更大的可释放的钙池， 对照细胞。 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： 在卟啉的存在下， 苯二氮卓受体在线粒体膜，开放 线粒体"巨通道"和随之而来的脉冲释放 Ca2+进入细胞质。 在研究中， 心脏和肝脏，暴露于卟啉和光被发现是 在抑制线粒体Ca2+摄取和 导致累积的Ca2+释放。 然而， 被环孢菌素阻断，环孢菌素抑制巨通道的开放， 并且确实涉及解偶联，如膜的荧光所示， 电位敏感染料JC-1。 因此， 光动力疗法在机制上比这种开放更广泛， 频道单独 这些关于细胞死亡中Ca2+的研究是为了 对这一过程的基本生物学的理解， 目的是设计干预措施，以防止不必要的细胞死亡， 老化过程中固定的有丝分裂后的组织。

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.