Shandong University Qilu Hospital Research Center for Cell Therapy, Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital of Shandong University, Jinan 250012, China.
Biochem Biophys Res Commun. 2012 Mar 30;420(1):78-83. doi: 10.1016/j.bbrc.2012.02.118. Epub 2012 Mar 1.
CYLD, a deubiquitinating enzyme (DUB), is a critical regulator of diverse cellular processes, ranging from proliferation and differentiation to inflammatory responses, via regulating multiple key signaling cascades such as nuclear factor kappa B (NF-κB) pathway. CYLD has been shown to inhibit vascular lesion formation presumably through suppressing NF-κB activity in vascular cells. However, herein we report a novel role of CYLD in mediating pro-inflammatory responses in vascular smooth muscle cells (VSMCs) via a mechanism independent of NF-κB activity. Adenoviral knockdown of Cyld inhibited basal and the tumor necrosis factor alpha (TNFα)-induced mRNA expression of pro-inflammatory cytokines including monocyte chemotactic protein-1 (Mcp-1), intercellular adhesion molecule (Icam-1) and interleukin-6 (Il-6) in rat adult aortic SMCs (RASMCs). The CYLD deficiency led to increases in the basal NF-κB transcriptional activity in RASMCs; however, did not affect the TNFα-induced NF-κB activity. Intriguingly, the TNFα-induced IκB phosphorylation was enhanced in the CYLD deficient RASMCs. While knocking down of Cyld decreased slightly the basal expression levels of IκBα and IκBβ proteins, it did not alter the kinetics of TNFα-induced IκB protein degradation in RASMCs. These results indicate that CYLD suppresses the basal NF-κB activity and TNFα-induced IκB kinase activation without affecting TNFα-induced NF-κB activity in VSMCs. In addition, knocking down of Cyld suppressed TNFα-induced activation of mitogen activated protein kinases (MAPKs) including extracellular signal-activated kinases (ERK), c-Jun N-terminal kinase (JNK), and p38 in RASMCs. TNFα-induced RASMC migration and monocyte adhesion to RASMCs were inhibited by the Cyld knockdown. Finally, immunochemical staining revealed a dramatic augment of CYLD expression in the injured coronary artery with neointimal hyperplasia. Taken together, our results uncover an unexpected role of CYLD in promoting inflammatory responses in VSMCs via a mechanism involving MAPK activation but independent of NF-κB activity, contributing to the pathogenesis of vascular disease.
CYLD 是一种去泛素化酶（DUB），是一种关键的调节因子，通过调节核因子 κB（NF-κB）途径等多种关键信号级联反应，调节细胞的增殖、分化和炎症反应等多种生理过程。已经表明 CYLD 通过抑制血管细胞中的 NF-κB 活性来抑制血管损伤形成。然而，在这里，我们报告了 CYLD 通过一种独立于 NF-κB 活性的机制，在介导血管平滑肌细胞（VSMCs）中的促炎反应方面的新作用。腺病毒介导的 Cyld 敲低抑制了大鼠成年主动脉平滑肌细胞（RASMCs）中基础和肿瘤坏死因子-α（TNFα）诱导的促炎细胞因子（包括单核细胞趋化蛋白-1（Mcp-1）、细胞间黏附分子（Icam-1）和白细胞介素-6（Il-6））的 mRNA 表达。CYLD 缺陷导致 RASMCs 中基础 NF-κB 转录活性增加；然而，不影响 TNFα 诱导的 NF-κB 活性。有趣的是，TNFα 诱导的 IκB 磷酸化在 CYLD 缺陷的 RASMCs 中增强。虽然 Cyld 的敲低略微降低了 IκBα 和 IκBβ 蛋白的基础表达水平，但不改变 TNFα 诱导的 RASMCs 中 IκB 蛋白降解的动力学。这些结果表明，CYLD 抑制 VSMCs 中的基础 NF-κB 活性和 TNFα 诱导的 IκB 激酶激活，而不影响 TNFα 诱导的 NF-κB 活性。此外，Cyld 的敲低抑制了 TNFα 诱导的丝裂原激活蛋白激酶（MAPKs）的激活，包括细胞外信号调节激酶（ERK）、c-Jun N 端激酶（JNK）和 p38 在 RASMCs 中的激活。TNFα 诱导的 RASMC 迁移和单核细胞与 RASMC 的黏附被 Cyld 的敲低所抑制。最后，免疫化学染色显示，在伴有新生内膜增生的损伤冠状动脉中，CYLD 的表达显著增加。总之，我们的结果揭示了 CYLD 通过一种涉及 MAPK 激活但不依赖于 NF-κB 活性的机制，在促进 VSMCs 中的炎症反应方面的意外作用，这有助于血管疾病的发病机制。
