Department of Neuroscience, Biomedicine, and Movement Sciences, Biological Chemistry Section, University of Verona, Strada Le Grazie 8, I-37134 Verona, Italy.
Instituto de Química Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Serrano 119, E-28006 Madrid, Spain.
Int J Mol Sci. 2021 Sep 17;22(18):10068. doi: 10.3390/ijms221810068.
Human Angiogenin (hANG, or ANG, 14.1 kDa) promotes vessel formation and is also called RNase 5 because it is included in the pancreatic-type ribonuclease (pt-RNase) super-family. Although low, its ribonucleolytic activity is crucial for angiogenesis in tumor tissues but also in the physiological development of the Central Nervous System (CNS) neuronal progenitors. Nevertheless, some ANG variants are involved in both neurodegenerative Parkinson disease (PD) and Amyotrophic Lateral Sclerosis (ALS). Notably, some pt-RNases acquire new biological functions upon oligomerization. Considering neurodegenerative diseases correlation with massive protein aggregation, we analyzed the aggregation propensity of ANG and of three of its pathogenic variants, namely H13A, S28N, and R121C. We found no massive aggregation, but wt-ANG, as well as S28N and R121C variants, can form an enzymatically active dimer, which is called ANG-D. By contrast, the enzymatically inactive H13A-ANG does not dimerize. Corroborated by a specific cross-linking analysis and by the behavior of H13A-ANG that in turn lacks one of the two His active site residues necessary for pt-RNases to self-associate through the three-dimensional domain swapping (3D-DS), we demonstrate that ANG actually dimerizes through 3D-DS. Then, we deduce by size exclusion chromatography (SEC) and modeling that ANG-D forms through the swapping of ANG N-termini. In light of these novelties, we can expect future investigations to unveil other ANG determinants possibly related with the onset and/or development of neurodegenerative pathologies.
人血管生成素（hANG，或 ANG，14.1 kDa）促进血管形成，也被称为 RNase 5，因为它包含在胰腺型核糖核酸酶（pt-RNase）超家族中。尽管含量较低，但它的核糖核酸酶活性对于肿瘤组织中的血管生成以及中枢神经系统（CNS）神经元祖细胞的生理发育至关重要。然而，一些 ANG 变体既参与神经退行性帕金森病（PD）又参与肌萎缩侧索硬化症（ALS）。值得注意的是，一些 pt-RNases 在寡聚化后获得新的生物学功能。考虑到神经退行性疾病与大量蛋白质聚集有关，我们分析了 ANG 及其三种致病性变体（H13A、S28N 和 R121C）的聚集倾向。我们没有发现大量聚集，但 wt-ANG 以及 S28N 和 R121C 变体可以形成具有酶活性的二聚体，称为 ANG-D。相比之下，无酶活性的 H13A-ANG 不能二聚化。通过特异性交联分析以及 H13A-ANG 的行为得到证实，H13A-ANG 反过来缺乏两个 His 活性位点残基之一，pt-RNases 通过三维结构域交换（3D-DS）自身缔合需要这两个 His 活性位点残基。我们证明 ANG 实际上通过 3D-DS 二聚化。然后，我们通过尺寸排阻色谱（SEC）和建模推断 ANG-D 通过 ANG N 末端的交换形成。鉴于这些新发现，我们可以期待未来的研究揭示其他可能与神经退行性病理发生和/或发展有关的 ANG 决定因素。
