Palmitate induces ER calcium depletion and apoptosis in mouse podocytes subsequent to mitochondrial oxidative stress.
Palmitate induces ER calcium depletion and apoptosis in mouse podocytes subsequent to mitochondrial oxidative stress.
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DOI：
10.1038/cddis.2015.331
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发表时间：
2015-11-19
影响因子：
9
通讯作者：
Park KS
中科院分区：
文献类型：
--
作者：
Xu S;Nam SM;Kim JH;Das R;Choi SK;Nguyen TT;Quan X;Choi SJ;Chung CH;Lee EY;Lee IK;Wiederkehr A;Wollheim CB;Cha SK;Park KS
足细胞的病理改变导致肾小球滤过屏障的一个重要组成部分的衰竭和慢性肾脏疾病中的蛋白尿。饱和游离脂肪酸（FFA）水平升高对各种组织有害，在糖尿病及其并发症（如糖尿病肾病中的蛋白尿）的进展中实施。在这里，我们研究了棕榈酸酯细胞毒性的分子机制，在培养的小鼠足细胞。与棕榈酸酯孵育剂量依赖性增加细胞溶质和线粒体活性氧，去极化线粒体膜电位，ATP合成受损，并引起细胞凋亡。软脂酸不仅诱发线粒体断裂，而且引起内质网（ER）的显着扩张。一致的是，棕榈酸上调ER应激蛋白，寡聚基质相互作用分子1（STIM 1）在质膜下的ER膜，取消cyclopiazonic酸诱导的胞浆Ca 2+增加由于腔ER Ca 2+的耗尽。棕榈酸诱导的ER Ca 2+耗竭和细胞毒性被脂肪酸转运蛋白FAT/CD 36的选择性抑制剂阻断。棕榈酸酯诱导的ER Ca 2+池的损失被磷脂酶C（PLC）抑制剂edelfosine逆转。棕榈酸依赖性激活PLC进一步证明了以下胞质易位的pleckstrin同源结构域的PLC在棕榈酸处理的足细胞。二酰基甘油（DAG）激酶的抑制剂，提高胞质DAG，强烈促进ER Ca 2+消耗低剂量棕榈酸酯。PKC抑制剂GF 109203 X部分阻止棕榈酸诱导的ER Ca 2+丢失。值得注意的是，线粒体抗氧化剂mitoTEMPO抑制棕榈酸诱导的PLC激活，ER Ca 2+耗竭和细胞毒性。棕榈酸酯引起足细胞的细胞骨架变化和白蛋白通透性增加，这也被mitoTEMPO阻断。这些数据表明，饱和FFA引起的氧化应激通过FAT/CD 36和PLC信号转导导致线粒体功能障碍和ER Ca 2+耗竭，可能导致足细胞损伤。
Pathologic alterations in podocytes lead to failure of an essential component of the glomerular filtration barrier and proteinuria in chronic kidney diseases. Elevated levels of saturated free fatty acid (FFA) are harmful to various tissues, implemented in the progression of diabetes and its complications such as proteinuria in diabetic nephropathy. Here, we investigated the molecular mechanism of palmitate cytotoxicity in cultured mouse podocytes. Incubation with palmitate dose-dependently increased cytosolic and mitochondrial reactive oxygen species, depolarized the mitochondrial membrane potential, impaired ATP synthesis and elicited apoptotic cell death. Palmitate not only evoked mitochondrial fragmentation but also caused marked dilation of the endoplasmic reticulum (ER). Consistently, palmitate upregulated ER stress proteins, oligomerized stromal interaction molecule 1 (STIM1) in the subplasmalemmal ER membrane, abolished the cyclopiazonic acid-induced cytosolic Ca2+ increase due to depletion of luminal ER Ca2+. Palmitate-induced ER Ca2+ depletion and cytotoxicity were blocked by a selective inhibitor of the fatty-acid transporter FAT/CD36. Loss of the ER Ca2+ pool induced by palmitate was reverted by the phospholipase C (PLC) inhibitor edelfosine. Palmitate-dependent activation of PLC was further demonstrated by following cytosolic translocation of the pleckstrin homology domain of PLC in palmitate-treated podocytes. An inhibitor of diacylglycerol (DAG) kinase, which elevates cytosolic DAG, strongly promoted ER Ca2+ depletion by low-dose palmitate. GF109203X, a PKC inhibitor, partially prevented palmitate-induced ER Ca2+ loss. Remarkably, the mitochondrial antioxidant mitoTEMPO inhibited palmitate-induced PLC activation, ER Ca2+ depletion and cytotoxicity. Palmitate elicited cytoskeletal changes in podocytes and increased albumin permeability, which was also blocked by mitoTEMPO. These data suggest that oxidative stress caused by saturated FFA leads to mitochondrial dysfunction and ER Ca2+ depletion through FAT/CD36 and PLC signaling, possibly contributing to podocyte injury.