CKIP-1 affects the polyubiquitination of Nrf2 and Keap1 via mediating Smurf1 to resist HG-induced renal fibrosis in GMCs and diabetic mice kidneys
CKIP-1 affects the polyubiquitination of Nrf2 and Keap1 via mediating Smurf1 to resist HG-induced renal fibrosis in GMCs and diabetic mice kidneys
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CKIP-1通过介导Smurf1影响Nrf2和Keap1的多泛素化以抵抗HG诱导的GMC和糖尿病小鼠肾脏的肾纤维化
DOI：
10.1016/j.freeradbiomed.2017.12.013
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发表时间：
2018-02-01
影响因子：
7.4
通讯作者：
Huang, Heqing
中科院分区：
文献类型：
--
作者：
Gong, Wenyan;Chen, Zhiquan;Huang, Heqing
我们前期的研究表明酪蛋白激酶2相互作用蛋白-1（CKIP-1）可促进核因子E2相关因子2（Nrf 2）/抗氧化反应元件（ARE）通路的激活，在抑制糖尿病肾病（DN）纤维化中发挥重要作用。然而，其潜在的机制仍然是未知的。本研究旨在探讨CKIP-1是否通过介导Smad泛素化调节因子1（Smurf 1）影响Nrf 2及其胞浆抑制剂Kelch样ECH相关蛋白1（Keap 1）的多聚泛素化，从而促进Nrf 2/ARE信号通路的激活，对抗高糖诱导的肾小球系膜细胞（GMCs）和糖尿病小鼠肾脏纤维化。结果显示，Smurf 1在HG诱导的GMC中表达增加，在1 h时表达最高。野生型Smurf 1质粒的过表达进一步促进HG诱导的纤维连接蛋白（FN）和细胞间粘附分子-1（ICAM-1）的过度表达，而Smurf 1质粒的缺失显著降低FN和ICAM-1的表达。CKIP-1的过表达降低了Nrf 2的K48连接的多聚泛素化，增加了K63连接的多聚泛素化，增强了Keap 1的K48连接的多聚泛素化，降低了K63连接的多聚泛素化，促进了Nrf 2/ARE通路的激活。Smurf 1的过表达增加了Nrf 2的K48连接的多聚泛素化，减少了K63连接的多聚泛素化，下调了Keap 1的K48连接的多聚泛素化，上调了K63连接的多聚泛素化，抑制了Nrf 2/ARE通路的激活。CKIP-1通过增加Smurf 1的泛素化而促进Smurf 1的降解。CKIP-1腺病毒感染可降低糖尿病小鼠Smurf 1水平，促进Nrf 2/ARE通路的激活，抑制活性氧（ROS）的产生，从而改善糖尿病小鼠肾功能衰竭。上述实验表明，CKIP-1通过影响Nrf 2和Keap 1的多泛素化，并通过下调Smurf 1促进Nrf 2-ARE通路，从而抵抗HG诱导的GMC和糖尿病小鼠肾脏FN和ICAM-1的上调。
Our previous study indicated that Casein kinase 2 interacting protein-1 (CKIP-1) could promote the activation of the nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway, playing a significant role in inhibiting the fibrosis of diabetic nephropathy (DN). However, the underlying mechanism is still unknown. Here, we investigated whether CKIP-1 affects the polyubiquitination of Nrf2 and its cytosolic inhibitor kelch like ECH-associated protein 1 (Keap1) via mediating Smad ubiquitylation regulatory factor-1 (Smurf1) to promote the activation of the Nrf2/ARE signaling and resist high glucose (HG)-induced renal fibrosis in glomerular mesangial cells (GMCs) and diabetic mice kidneys. Results showed that the expression of Smurf1 increased in HG-induced GMCs, with a paramount upregulation at 1 h. Overexpression of wild-type Smurf1 plasmid further promoted the HG-induced the over-production of fibronectin (FN) and intercellular adhesionmolecule-1 (ICAM-1), and depletion of Smurf1 dramatically reduced the expression of FN and ICAM-1. Overexpression of CKIP-1 decreased the K48-linked polyubiquitination and increased the K63-linked polyubiquitination of Nrf2 as well as enhanced the K48-linked polyubiquitination and reduced K63-linked polyubiquitination of Keap1, promoting the activation of the Nrf2/ARE pathway. Overexpression of Smurf1 increased the K48-linked polyubiquitination and decreased the K63-linked polyubiquitination of Nrf2, and down-regulated the K48-linked polyubiquitination and up-regulated the K63-linked polyubiquitination of Keap1, inhibiting the activation of the Nrf2/ARE pathway. CKIP-1 promoted the degradation of Smurf1 by increasing the ubiquitination of Smurf1. Treatment of CKIP-1 adenovirus infection reduced the Smurf1 levels, promoted the activation of the Nrf2/ARE pathway as well as suppressed the production of reactive oxygen species (ROS), and then improved the failure of renal function of diabetic mice. Experiments above suggested that CKIP-1 affects the polyubiquitination of Nrf2 and Keap1 and promotes the Nrf2-ARE pathway through down-regulating Smurf1 to resist HG-induced up-regulation of FN and ICAM-1 in GMCs and diabetic mice kidneys.