DETERMINANTS FOR TOXICITY OF CALCINEURIN INHIBITORS

免疫抑制剂对钙调磷酸酶活性的抑制作用 CyA和FK506引起这些药物的治疗和毒性作用。 毒品 本提案的主要目的是确定如何 不同细胞的参数影响CyA和FK506的效力， 钙调磷酸酶抑制剂。 第二个目标是确定 钙调磷酸酶抑制的不同补偿能力 有助于细胞对CyA毒性作用的特异性敏感性 FK506 从长远来看，这些信息将有助于减少 CyA/FK506毒副作用的数量和严重程度，并扩大 使用钙调磷酸酶抑制剂的免疫抑制疗法的有用性。 环孢菌素A（CyA）和FK506显著提高了 移植后移植物存活率。 这些药物用于 几乎支持今天执行的所有传输， 药物毒性，可能导致治疗停止， 使移植物和病人处于危险之中 治疗和毒性 这些药物的作用是细胞类型和组织选择性的， CyA/FK506作为钙调磷酸酶抑制剂效力的特异性差异 预计有助于选择性。 钙调磷酸酶抑制 CyA/FK506在机制上是复杂的，依赖于 药物和其蛋白质辅因子两者的浓度（称为 亲免素）的抑制作用。 钙调神经磷酸酶的活性物质 抑制是一种药物-亲免蛋白复合物， Ca~（2+）依赖性。 这项研究的假设是， 细胞内亲免素含量、Ca2+浓度持续时间和幅度 通过测定CyA/FK506作为钙调磷酸酶抑制剂的瞬时值，确定CyA/FK506作为钙调磷酸酶抑制剂的效力。 进一步假设CyA的毒性既取决于 钙调磷酸酶抑制的程度和细胞的能力， 补偿钙调磷酸酶活性的损失。 具体目标 项目有： I. 为了确定钙调神经磷酸酶是否与CyA-亲环蛋白和FK506结合， FKPB复合物是由存在于非钙离子中的Ca2+浓度支持的。 活跃的细胞 二. 为了定量亲环素浓度依赖性， CyA对钙调磷酸酶的抑制作用，并确定 细胞中亲环蛋白或亲环蛋白的类型影响CyA效力。 三.为了测量组织和细胞的补偿能力， 钙调神经磷酸酶抑制和识别独特的钙调神经磷酸酶底物， 对CyA敏感的细胞。 预计了解其机制 钙调磷酸酶抑制将阐明为什么某些器官是靶点， 免疫抑制剂的毒性作用，将揭示更多更好的 治疗干预的部位，并将指出 治疗可能是最成功的改善CyA/FK506侧 方面的影响.

Inhibition of calcineurin phosphatase activity by the immunosuppressants CyA and FK506 causes both the therapeutic and toxic effects of these drugs. The primary objective of this proposal is to determine how parameters which vary from cell to cell affect CyA and FK506 potency as calcineurin inhibitors. A second objective is to determine if differential abilities to compensate for calcineurin inhibition contribute to the cell type-specific sensitivity to toxic effects of CyA and FK506. In the long term, this information will help reduce the number and severity of CyA/FK506 toxic side effects and expand the usefulness of immunosuppressive therapy with calcineurin inhibitors. Cyclosporin A (CyA) and FK506 have dramatically increased the success rate for graft survival after transplantation. These drugs are used to support virtually every transport performed today, despite severe toxicity of the drugs which can result in withdrawal of treatment and place the graft and patients at risk. Both the therapeutic and toxic effects of these drugs are cell type and tissue selective, with cell type specific differences in potency of CyA/FK506 as calcineurin inhibitors predicted to contribute to the selectivity. Calcineurin inhibition by CyA/FK506 is mechanistically complex, being dependent on the concentrations of both the drug and its protein cofactor (referred to as an immunophilin) in the inhibition. The active species for calcineurin inhibition is a drug-immunophilin complex which binds to calcineurin in a Ca2+-dependent manner. The hypothesis for this study is that the cellular content of immunophilin, and the duration and amplitude of Ca2+ transients, determine the potency of CyA/FK506 as calcineurin inhibitors. It is further hypothesized that CyA toxicity is dependent both on the degree of calcineurin inhibition and the ability of the cell to compensate for loss of calcineurin activity. Specific aims of this project are: I. To determine if calcineurin binding to CyA-cyclophilin and FK506- FKPB complexes is supported by the Ca2+ concentrations present in non- active cells. II. To quantitate the cyclophilin concentration dependence of calcineurin inhibition by CyA and determine if the cell content of cyclophilin or the type of cyclophilin in the cell affect CyA potency. III. To measure the capacity of tissues and cells to compensate for calcineurin inhibition and the identify unique calcineurin substrates in cells which are sensitive to CyA. It is anticipated that an understanding of the mechanisms underlying calcineurin inhibition will clarify why certain organs are targets for the toxic effects of immunosuppressants, will reveal more and better sites for therapeutic intervention and will indicate which adjuvant therapies might be most successful in ameliorating the CyA/FK506 side effects.