衔接蛋白DAB2在硬皮病纤维化进程中的作用及机制研究

Systemic sclerosis (SSc) is a fibrosis-related autoimmune disease characterized by cutaneous and internal organ fibrosis. The pathogenesis of SSc is complicated, in which TGF-β signaling plays an important role, and adaptor protein DAB2 could regulate TGF-β signaling through binding to Smad protein. The applicant has found the fibrotic process of SSc could be alleviated by inhibiting TGF-β signaling in her previous research (Lab Invest 2017, Sci Rep 2016). Further research indicated the expression of DAB2 was increased in the SSc mouse skin, SSc patients’ skin and immune cells. Inhibition of DAB2 could decrease collagen expression and TGF-β signaling activation in SSc dermal fibroblasts, indicating DAB2 may play an important role in SSc fibrosis. This project plan to prove the function of DAB2 in SSc by increasing or decreasing the expression of DAB2 in SSc mouse model, and the implantation of further in vivo and in vitro studies will indicate the effect and mechanism of DAB2 on fibroblasts activation, TGF-β signaling regulation as well as its effect on immune cell differentiation and TGF-β expression. The applicant will explore the detailed mechanism of how DAB2 regulate TGF-β signaling in the fibrotic process of SSc and provide the theoretic basis for clinical translational study.

硬皮病是以皮肤增厚和纤维化为特征并累及内脏器官的自身免疫性纤维化疾病，发病机制复杂，TGF-β通路在其中发挥关键作用，而衔接蛋白DAB2可通过与Smad蛋白结合介导TGF-β信号转导。申请人前期研究发现，阻断TGF-β通路可缓解硬皮病纤维化进程（Lab Invest 2017，Sci Rep 2016）；进一步研究发现：DAB2在硬皮病小鼠皮肤、患者皮肤及免疫细胞中均表达升高；干扰DAB2可降低硬皮病皮肤成纤维细胞胶原表达及TGF-β通路活性，提示DAB2在硬皮病纤维化中可能具重要作用。本项目拟通过在硬皮病小鼠中升高或降低DAB2表达以证实DAB2在硬皮病纤维化中的作用；进一步通过体内及体外实验观察DAB2对成纤维细胞活化、TGF-β通路活性的调控作用及机制、及对免疫细胞分化及TGF-β表达的影响，阐释DAB2调控TGF-β通路参与硬皮病纤维化的具体作用机制，为临床转化提供理论依据。

硬皮病是以皮肤增厚和纤维化为特征并累及内脏器官的自身免疫性纤维化疾病，发病机制复杂且迄今仍未明确，目前尚无FDA批准的治疗药物。衔接蛋白DAB2可通过与Smad蛋白结合介导TGF-β信号转导，我们的前期研究发现，阻断TGF-β通路可缓解硬皮病纤维化进程，干扰DAB2可降低硬皮病皮肤成纤维细胞胶原表达及TGF-β通路活性。为进一步揭示DAB2等基因参与调控硬皮病纤维化的分子机制，本项目利用临床样本、动物模型、细胞模型对硬皮病纤维化进行了系统的研究，主要研究成果包括：1）DAB2在硬皮病患者皮肤组织中高表达；在硬皮病小鼠中降低DAB2表达可有效抑制博来霉素诱导的硬皮病小鼠皮肤炎症及纤维化；体外实验显示干扰DAB2表达有效抑制成纤维细胞活化；进一步RNA-seq转录组学表明，DAB2可能是通过调控TGF-β通路及粘附连接信号通路发挥抗硬皮病纤维化的作用，且ITGB1在其中发挥了重要作用。2）为进一步揭示硬皮病发病机制，对粘附连接等相关的基因，包括ZYX、GAB1、CNN1，在硬皮病纤维化中的作用及机制进行了研究。3）此外，我们对相关药物治疗纤维化的作用进行了研究，例如丹酚酸B、二甲双胍。本项目的实施，使我们对硬皮病纤维化发生发展过程中DAB2等基因的作用及机制拥有了更全面的认识，推动了对硬皮病发病机制的理解，对于疾病机制的揭示及治疗药物的开发具有重要意义。