Mechanism of cyclosporin-induced inhibition of intracellular collagen degradation
Mechanism of cyclosporin-induced inhibition of intracellular collagen degradation
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DOI：
10.1074/jbc.m010298200
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发表时间：
2001-04-27
影响因子：
4.8
通讯作者：
McCulloch, CAG
中科院分区：
文献类型：
--
作者：
Arora, PD;Silvestri, L;McCulloch, CAG
免疫抑制剂环孢菌素A（CsA）通过成纤维细胞的细胞内吞噬途径显著抑制胶原降解，这种作用可导致大量牙龈过度生长。我们使用胶原吞噬作用的胶原珠模型来确定CsA是否通过阻断钙从内质网（ER）和线粒体钙库的流出来抑制内化。CsA引起胶原蛋白包被（但不是牛血清白蛋白包被）珠粒的吞噬作用的剂量依赖性抑制。用BAPTA/AM螯合细胞内Ca ~（2+）或用毒胡萝卜素抑制ER库的Ca ~（2+）ATP酶可降低胶原珠的吞噬作用。通过比率荧光测定法测量细胞内钙显示对胶原包被珠的反应增加。与CsA或thapsipargin预孵育导致胶原珠刺激引起的细胞内钙升高降低>3倍。直接测量线粒体和内质网中的Ca 2+显示，CsA仅轻微抑制胶原珠诱导的线粒体钙释放，但几乎完全阻断内质网中的钙释放。我们用慢性溴化乙锭治疗减少线粒体的数量，以测试ER/线粒体相互作用的重要性。在这些细胞中，CsA延迟胶原珠诱导的线粒体钙放电。总的来说，这些数据表明，CsA抑制胶原蛋白的吞噬作用，通过阻断钙释放从ER商店，并可能扰乱ER和线粒体之间的功能相互作用，调节钙储存。
The immunosuppressant cyclosporin A (CsA) markedly inhibits collagen degradation by an intracellular phagocytic pathway in fibroblasts, an: effect that can lead to massive gingival overgrowth. We used a collagen bead model of collagen phagocytosis to determine whether CsA inhibits internalization by blocking efflux of calcium from endoplasmic reticulum (ER) and mitochondrial calcium stores. CsA caused dose-dependent inhibition of phagocytosis of collagen-coated (but not bovine serum albumin-coated) beads. Chelation of intracellular Ca2+ with BAPTA/AM or inhibition of Ca2+ ATPase of ER stores with thapsigargin reduced collagen bead phagocytosis. Measurement of intracellular calcium by ratio fluorometry showed increases in response to collagen-coated beads. Preincubation with CsA or thapsipargin caused a >3-fold decrease in intracellular calcium elevations in response to stimulation with collagen beads. Direct measurements of Ca2+ in mitochondrial and ER stores showed that CsA only slightly inhibited collagen bead-induced discharge of calcium from mitochondria, but almost completely blocked discharge from ER stores. We reduced the numbers of mitochondria with chronic ethidium bromide treatment to test for the importance of ER/mitochondrial interactions. In these cells, CsA delayed collagen bead-induced calcium discharge from mitochondria. Collectively, these data indicate that CsA inhibits collagen phagocytosis by blocking calcium release from ER stores and may perturb functional interactions between the ER and mitochondria that regulate calcium stores.