Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany Department of Rheumatology, 1st Faculty of Medicine, Institute of Rheumatology, Charles University, Prague, Czech Republic.
Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany.
Ann Rheum Dis. 2016 Mar;75(3):609-16. doi: 10.1136/annrheumdis-2014-206234. Epub 2015 Jan 20.
Tribbles homologue 3 (TRB3) is a pseudokinase that modifies the activation of various intracellular signalling pathways to control fundamental processes extending from mitosis and cell activation to apoptosis and modulation of gene expression. Here, we aimed to analyse the role of TRB3 in fibroblast activation in systemic sclerosis (SSc).
The expression of TRB3 was quantified by quantitative PCR, western blot and immunohistochemistry. The role of TRB3 was analysed in cultured fibroblasts and in experimental fibrosis using small interfering RNA (siRNA)-mediated knockdown and overexpression of TRB3.
TRB3 expression was increased in fibroblasts of patients with SSc and in murine models of SSc in a transforming growth factor-β (TGF-β)/Smad-dependent manner. Overexpression of TRB3 stimulated canonical TGF-β signalling and induced an activated phenotype in resting fibroblasts. In contrast, knockdown of TRB3 reduced the profibrotic effects of TGF-β and decreased the collagen synthesis. Moreover, siRNA-mediated knockdown of TRB3 exerted potent antifibrotic effects and ameliorated bleomycin as well as constitutively active TGF-β receptor I-induced fibrosis with reduced dermal thickening, decreased hydroxyproline content and impaired myofibroblast differentiation.
The present study characterises TRB3 as a novel profibrotic mediator in SSc. TGF-β induces TRB3, which in turn activates canonical TGF-β/Smad signalling and stimulates the release of collagen, thereby inducing a positive feedback loop that may contribute to aberrant TGF-β signalling in SSc.
Tribbles 同源物 3（TRB3）是一种假激酶，可调节各种细胞内信号通路的激活，以控制从有丝分裂和细胞激活到细胞凋亡和基因表达调控的基本过程。在这里，我们旨在分析 TRB3 在系统性硬化症（SSc）中纤维母细胞激活中的作用。
通过定量 PCR、western blot 和免疫组织化学定量分析 TRB3 的表达。使用小干扰 RNA（siRNA）介导的 TRB3 敲低和过表达分析 TRB3 在培养的成纤维细胞中和实验性纤维化中的作用。
TRB3 在 SSc 患者的成纤维细胞中和 TGF-β/Smad 依赖性转化生长因子-β（TGF-β）的小鼠模型中表达增加。TRB3 的过表达刺激了经典的 TGF-β 信号通路，并诱导静止成纤维细胞呈现激活表型。相反，TRB3 的敲低减少了 TGF-β 的促纤维化作用，并降低了胶原合成。此外，siRNA 介导的 TRB3 敲低发挥了强大的抗纤维化作用，并改善了博来霉素以及组成性激活 TGF-β 受体 I 诱导的纤维化，减少了皮肤增厚、羟脯氨酸含量降低和肌成纤维细胞分化受损。
本研究将 TRB3 描述为 SSc 中的一种新型促纤维化介质。TGF-β 诱导 TRB3，进而激活经典的 TGF-β/Smad 信号通路并刺激胶原释放，从而诱导正反馈环，这可能有助于 SSc 中异常的 TGF-β 信号转导。
