Molecular mechanisms of heparanase-2 (hpa-2) in endothelial cell activation, inflammation and albuminuria

内皮细胞被一层称为糖萼的高度糖基化的糖蛋白所覆盖。内皮糖萼在许多生理肾小球机制中起重要作用，糖萼损伤可导致肾脏疾病和蛋白尿。蛋白聚糖可以由肝素酶调节，肝素酶是唯一已知的能够降解硫酸肝素（HS）糖胺聚糖的哺乳动物内糖苷酶。肝素酶对HS的酶降解深刻影响了许多生理和病理过程，包括形态发生、新生血管形成、肿瘤发生以及免疫反应性和炎症。最近，一种新的肝素酶hpa-2被克隆出来。最重要的是，Hpa2c抑制肝素酶的酶活性，可能是由于它对肝素和HS的高亲和力以及它与肝素酶物理结合的能力。然而，迄今为止，hpa-2在肾脏疾病中的功能作用及其在内皮细胞功能和蛋白尿发病机制中的可能作用尚未得到研究。因此，我们希望研究肝素酶-2 （hpa-2）的分子功能，并验证以下假设：hpa-2(1)阻止肝素酶-1脱落内皮糖萼，(2)拮抗并降低肝素酶-1在细胞内的作用，(3)减少细胞因子和生长因子（VEGF， FGF）的细胞内信号传导和效应机制，(4)从而防止糖尿病和脓毒症等病理条件下的肾脏和血管损伤。为此，我们将使用(1)一种新开发的斑马鱼蛋白尿动物模型，(2)内皮细胞的新型微循环系统，并且我们已经建立了(3)糖盏的新型染色技术和(4)肾疾病小鼠模型中hpa-2的病毒转染。我们的研究不仅对了解内皮糖萼及其调控具有重要意义，而且可能导致糖尿病肾病和败血症的新治疗策略。

The endothelium is covered with a layer of heavily glycosylated glycoproteins called the glycocalyx. The endothelial glycocalyx plays an important role in many physiological glomerular mechanisms and damage to the glycocalyx results in renal disease and proteinuria. Proteoglycans can be regulated by heparanase, the only known mammalian endoglycosidase capable of degrading heparan sulfate (HS) glycosaminoglycan. Enzymatic degradation of HS by heparanase profoundly affects numerous physiological and pathological processes, including morphogenesis, neovascularization, tumorigenesis as well as immune reactivity and inflammation. Recently, a novel heparanase, hpa-2 has been cloned. Most importantly, Hpa2c inhibits heparanase enzymatic activity, likely due to its high affinity to heparin and HS and its ability to associate physically with heparanase. However, the functional role of hpa-2 in renal disease and its possible role in the pathogenesis of endothelial cell function and albuminuria have not been investigated so far. We therefore want to study the molecular function of heparanase-2 (hpa-2) and test the hypothesis that hpa-2 (1) prevents the shedding of the endothelial glycocalyx by heparanase-1, (2) antagonizes and reduces the intracellular effects of heparanase-1, (3) reduces the intracelluar signaling and effector mechanisms of cytokines and growth factors (VEGF, FGF), and (4) thereby prevents renal and vascular damage under pathological conditions such as diabetes and sepsis. For this purpose, we will use (1) a newly developed animal model for proteinuria in the zebrafish, (2) a novel microcirculation system for endothelial cells, and we have established (3) novel staining techiques for glycocalyx and (4) viral transfection of hpa-2 in mouse models of renal disease. Our research is not only improtnat for the understanding of endothelial glycocalyx and ist regulation but may also lead to novel treatment strategies in diabetic nephropathy and sepsis.