组织蛋白酶S介导的PPAR-γ信号通路在老年缺血性血管再生中的作用及分子机制研究

治疗老年缺血性疾病成为医学专家亟需解决的难题。过氧化物酶体增殖物激活受体γ（PPAR-γ）是通过核内靶基因调控多种细胞分化及增殖效应。组织蛋白酶S（CatS）通过修饰/分解各种生物活性物质调控内皮细胞的生物活性。本研究利用CatS和半胱氨酸蛋白酶抑制剂（CystC）基因敲除小鼠制备下肢缺血模型及缺氧应激暴露的内皮细胞模型，探讨CatS介导的PPAR-γ活性及其信号通路调控血管再生的机制；通过基因沉默（siCatS）、基因转染（ad-CystC）、骨髓移植等进一步探索CatS调控PPAR-γ激活以及血管再生机制；再通过不同周龄小鼠的下肢缺血性血管再生模型，探讨老化对CatS活性、PPAR-γ依赖的PI3K/Akt/eNOS信号通路的影响。本研究阐明老化降低CatS活性、削弱PPAR-γ激活导致血管再生能力降低的机制，为预防和治疗老年下肢缺血性疾病以及开发新药物奠定基础。

Cysteine protease cathepsin S (CatS) is one of the most potent mammalian elastases. We have previously shown an increased expression of CatS of atherosclerotic lesion. Recently, it is highlighted that CatS modify and degrade intracellular and extracellular various angiogenic substances to contribute to the pathological conditions. However, the roles of CatS in pathophysiological angiogenesis are poorly understood in aged humans and animals. Young (8-weeks) male CatS+/+ and CatS-/-mice were underwent hindlimb ischemic surgery, and were then processed for functional (blood-flow recovery), morphological and biochemical studies at specific time points to explore the possibility that CatS deficiency impaired ischemia-induced angiogenesis associated with the reduction in peroxisome proliferator-activated receptor-gamma (PPAR-γ) activation and the related signaling pathway activity. To explore the mechanisms of aging-related impaired angiogenesis, both old (96-weeks) genotype mice were also applied to examinations. In vitro, we will investigate whether genetic and pharmacological interventions of CatS impair cellular angiogenic action via PPAR-γ activation in cultured endothelial cell under hypoxia. We will further investigate the role of CatS in PPAR-γ activation in several vascular cell lines by a short-interfering RNA against to siCatS and Ad-CystC. Finally, we will investigate the roles of bone-marrow(BM)-derived CatS using BM transplantation. Our findings will help understanding molecular mechanisms of the impairment of aging-related angiogenesis, and provide new therapeutic approach to improve ischemia-induced neovascularization in aged humans..Key words: Cathepsin S；Hindlimb ischemic　disease；Aging； Neovascularization ； Hypoxia