Lysyl oxidases are major actors of microenvironment and extracellular matrix (ECM) remodeling. These cross-linking enzymes are thus involved in many aspects of physiopathology, including tumor progression, fibrosis and cardiovascular diseases. We have already shown that Lysyl Oxidase-Like 2 (LOXL2) regulates collagen IV deposition by endothelial cells and angiogenesis. We here provide evidence that LOXL2 also affects deposition of other ECM components, including fibronectin, thus altering structural and mechanical properties of the matrix generated by endothelial cells. LOXL2 interacts intracellularly and directly with collagen IV and fibronectin before incorporation into ECM fibrillar structures upon exocytosis, as demonstrated by TIRF time-lapse microscopy. Furthermore, surface plasmon resonance experiments using recombinant scavenger receptor cysteine-rich (SRCR) domains truncated for the catalytic domain demonstrated their direct binding to collagen IV. We thus used directed mutagenesis to investigate the role of LOXL2 catalytic domain. Neither enzyme activity nor catalytic domain were necessary for collagen IV deposition and angiogenesis, whereas the SRCR domains were effective for these processes. Finally, surface coating with recombinant SRCR domains restored deposition of collagen IV by LOXL2-depleted cells. We thus propose that LOXL2 SRCR domains orchestrate scaffolding of the vascular basement membrane and angiogenesis through interactions with collagen IV and fibronectin, independently of the enzymatic cross-linking activity.

中文翻译：

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赖氨酰氧化酶-Like2的清道夫受体半胱氨酸丰富域通过非催化支架机制调节内皮细胞ECM和血管生成。

赖氨酰氧化酶是微环境和细胞外基质（ECM）重塑的主要参与者。这些交联酶因此涉及生理病理学的许多方面，包括肿瘤进展，纤维化和心血管疾病。我们已经显示，Lysyl Oxidase-Like 2（LOXL2）通过内皮细胞和血管生成调节胶原IV沉积。我们在这里提供证据表明LOXL2还影响其他ECM成分（包括纤连蛋白）的沉积，从而改变了内皮细胞生成的基质的结构和机械性能。如通过TIRF延时显微镜观察，LOXL2在胞吐作用并入ECM纤维状结构之前，会与胶原蛋白IV和纤连蛋白直接在细胞内相互作用。此外，表面等离振子共振实验使用截短为催化结构域的重组清道夫受体富半胱氨酸（SRCR）结构域证明了它们与胶原IV的直接结合。因此，我们使用定向诱变来研究LOXL2催化域的作用。胶原蛋白IV沉积和血管生成既不需要酶活性也不不需要催化域，而SRCR域对这些过程有效。最后，用重组SRCR结构域进行表面包被可恢复LOXL2耗尽细胞对胶原蛋白IV的沉积。因此，我们提出LOXL2 SRCR结构域通过与胶原IV和纤连蛋白的相互作用来独立于酶的交联活性，来协调血管基底膜的支架和血管生成。