Kubala Lukáš, Kolářová Hana, Víteček Jan, Kremserová Silvie, Klinke Anna, Lau Denise, Chapman Anna L P, Baldus Stephan, Eiserich Jason P
Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
Biochim Biophys Acta. 2013 Oct;1830(10):4524-36. doi: 10.1016/j.bbagen.2013.05.024. Epub 2013 May 23.
Myeloperoxidase (MPO) is an abundant hemoprotein expressed by neutrophil granulocytes that is recognized to play an important role in the development of vascular diseases. Upon degranulation from circulating neutrophil granulocytes, MPO binds to the surface of endothelial cells in an electrostatic-dependent manner and undergoes transcytotic migration to the underlying extracellular matrix (ECM). However, the mechanisms governing the binding of MPO to subendothelial ECM proteins, and whether this binding modulates its enzymatic functions are not well understood.
We investigated MPO binding to ECM derived from aortic endothelial cells, aortic smooth muscle cells, and fibroblasts, and to purified ECM proteins, and the modulation of these associations by glycosaminoglycans. The oxidizing and chlorinating potential of MPO upon binding to ECM proteins was tested.
MPO binds to the ECM proteins collagen IV and fibronectin, and this association is enhanced by the pre-incubation of these proteins with glycosaminoglycans. Correspondingly, an excess of glycosaminoglycans in solution during incubation inhibits the binding of MPO to collagen IV and fibronectin. These observations were confirmed with cell-derived ECM. The oxidizing and chlorinating potential of MPO was preserved upon binding to collagen IV and fibronectin; even the potentiation of MPO activity in the presence of collagen IV and fibronectin was observed.
Collectively, the data reveal that MPO binds to ECM proteins on the basis of electrostatic interactions, and MPO chlorinating and oxidizing activity is potentiated upon association with these proteins.
Our findings provide new insights into the molecular mechanisms underlying the interaction of MPO with ECM proteins.
髓过氧化物酶（MPO）是一种由中性粒细胞表达的丰富血红素蛋白，已知其在血管疾病的发展中起重要作用。从循环中的中性粒细胞脱颗粒后，MPO以静电依赖的方式结合到内皮细胞表面，并通过转胞吞作用迁移到下层的细胞外基质（ECM）。然而，MPO与内皮下ECM蛋白结合的机制以及这种结合是否调节其酶功能尚不清楚。
我们研究了MPO与源自主动脉内皮细胞、主动脉平滑肌细胞和成纤维细胞的ECM以及纯化的ECM蛋白的结合，以及糖胺聚糖对这些结合的调节。测试了MPO与ECM蛋白结合后的氧化和氯化能力。
MPO与ECM蛋白IV型胶原和纤连蛋白结合，这些蛋白与糖胺聚糖预孵育可增强这种结合。相应地，孵育过程中溶液中过量的糖胺聚糖会抑制MPO与IV型胶原和纤连蛋白的结合。这些观察结果在细胞来源的ECM中得到证实。MPO与IV型胶原和纤连蛋白结合后，其氧化和氯化能力得以保留；甚至在存在IV型胶原和纤连蛋白的情况下还观察到MPO活性增强。
总体而言，数据表明MPO基于静电相互作用与ECM蛋白结合，并且与这些蛋白结合后MPO的氯化和氧化活性增强。
我们的研究结果为MPO与ECM蛋白相互作用的分子机制提供了新的见解。
