New insights into circulating FABP4: Interaction with cytokeratin 1 on endothelial cell membranes
New insights into circulating FABP4: Interaction with cytokeratin 1 on endothelial cell membranes
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DOI：
10.1016/j.bbamcr.2015.09.002
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发表时间：
2015-11-01
影响因子：
5.1
通讯作者：
Masana, Lluis
中科院分区：
文献类型：
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作者：
Saavedra, Paula;Girona, Josefa;Masana, Lluis
脂肪酸结合蛋白 4 (FABP4) 是一种脂肪组织分泌的脂肪因子，参与能量代谢和炎症的调节。在具有心血管危险因素的个体中已检测到循环 FABP4 水平升高。最近的研究表明，FABP4对外周组织有直接作用，特别是促进血管功能障碍；然而，其作用机制尚不清楚。这项工作的目的是评估外源 FABP4 与内皮细胞质膜之间的特异性相互作用。免疫荧光测定表明，外源 FABP4 沿着人脐静脉内皮细胞 (HUVEC) 的质膜定位，与质膜蛋白特异性相互作用。抗 FABP4 免疫印迹揭示了两种含有 FABP4 及其推定受体的共价蛋白复合物；这些复合物的大小约为 108 kDa 和 77 kDa。蛋白质组学和质谱实验表明细胞角蛋白 1 (CK1) 是 FABP4 结合蛋白。抗 CK1 免疫印迹证实了 CK1 的存在。在 HAEC、HCASMC、HepG2 细胞和 THP-1 细胞中也检测到 FABP4-CK1 复合物。 BMS309403 的药理学 FABP4 抑制导致这些复合物的形成略有减少，表明脂肪酸可能在 FABP4 功能中发挥作用。此外，我们证明外源 FABP4 穿过质膜进入 HUVEC 的细胞质和细胞核。这些发现表明外源 FABP4 与质膜蛋白（特别是 CK1）相互作用。这些数据有助于我们目前对循环 FABP4 作用机制的了解。 (C) 2015 年由 Elsevier B.V. 出版
Fatty acid-binding protein 4 (FABP4) is an adipose tissue-secreted adipokine that is involved in the regulation of energetic metabolism and inflammation. Increased levels of circulating FABP4 have been detected in individuals with cardiovascular risk factors. Recent studies have demonstrated that FABP4 has a direct effect on peripheral tissues, specifically promoting vascular dysfunction; however, its mechanism of action is unknown. The objective of this work was to assess the specific interactions between exogenous FABP4 and the plasma membranes of endothelial cells. Immunofluorescence assays showed that exogenous FABP4 localized along the plasma membranes of human umbilical vein endothelial cells (HUVECs), interacting specifically with plasma membrane proteins. Anti-FABP4 immunoblotting revealed two covalent protein complexes containing FABP4 and its putative receptor; these complexes were approximately 108 kDa and 77 kDa in size. Proteomics and mass spectrometry experiments revealed that cytokeratin 1 (CK1) was the FABP4-binding protein. An anti-CK1 immunoblot confirmed the presence of CK1. FABP4-CK1 complexes were also detected in HAECs, HCASMCs, HepG2 cells and THP-1 cells. Pharmacological FABP4 inhibition by BMS309403 results in a slight decrease in the formation of these complexes, indicating that fatty acids may play a role in FABP4 functionality. In addition, we demonstrated that exogenous FABP4 crosses the plasma membrane to enter the cytoplasm and nucleus in HUVECs. These findings indicate that exogenous FABP4 interacts with plasma membrane proteins, specifically CK1. These data contribute to our current knowledge regarding the mechanism of action of circulating FABP4. (C) 2015 Published by Elsevier B.V.