Department of Biomedicine, Aarhus University, Aarhus, Denmark.
CDL Research, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.
J Allergy Clin Immunol. 2023 Nov;152(5):1218-1236.e9. doi: 10.1016/j.jaci.2023.04.023. Epub 2023 Jun 9.
Patients with hereditary angioedema experience recurrent, sometimes life-threatening, attacks of edema. It is a rare genetic disorder characterized by genetic and clinical heterogenicity. Most cases are caused by genetic variants in the SERPING1 gene leading to plasma deficiency of the encoded protein C1 inhibitor (C1INH). More than 500 different hereditary angioedema-causing variants have been identified in the SERPING1 gene, but the disease mechanisms by which they result in pathologically low C1INH plasma levels remain largely unknown.
The aim was to describe trans-inhibitory effects of full-length or near full-length C1INH encoded by 28 disease-associated SERPING1 variants.
HeLa cells were transfected with expression constructs encoding the studied SERPING1 variants. Extensive and comparative studies of C1INH expression, secretion, functionality, and intracellular localization were carried out.
Our findings characterized functional properties of a subset of SERPING1 variants allowing the examined variants to be subdivided into 5 different clusters, each containing variants sharing specific molecular characteristics. For all variants except 2, we found that coexpression of mutant and normal C1INH negatively affected the overall capacity to target proteases. Strikingly, for a subset of variants, intracellular formation of C1INH foci was detectable only in heterozygous configurations enabling simultaneous expression of normal and mutant C1INH.
We provide a functional classification of SERPING1 gene variants suggesting that different SERPING1 variants drive the pathogenicity through different and in some cases overlapping molecular disease mechanisms. For a subset of gene variants, our data define some types of hereditary angioedema with C1INH deficiency as serpinopathies driven by dominant-negative disease mechanisms.
遗传性血管性水肿患者会反复发作，有时危及生命的水肿发作。这是一种罕见的遗传性疾病，具有遗传和临床异质性。大多数病例是由 SERPING1 基因中的遗传变异引起的，导致编码蛋白 C1 抑制剂（C1INH）的血浆缺乏。在 SERPING1 基因中已经发现了超过 500 种不同的遗传性血管性水肿致病变异，但它们导致病理性低 C1INH 血浆水平的疾病机制在很大程度上仍然未知。
本研究旨在描述由 28 种 SERPING1 相关变体编码的全长或近全长 C1INH 的反式抑制作用。
用编码研究 SERPING1 变体的表达构建体转染 HeLa 细胞。对 C1INH 的表达、分泌、功能和细胞内定位进行了广泛而比较的研究。
我们的研究结果描述了一组 SERPING1 变体的功能特性，这些变体可将研究的变体分为 5 个不同的簇，每个簇都包含具有特定分子特征的变体。除了 2 个变体外，我们发现突变和正常 C1INH 的共表达对靶向蛋白酶的整体能力产生负面影响。引人注目的是，对于一组变体，只有在杂合配置中才能检测到 C1INH 焦点的细胞内形成，从而能够同时表达正常和突变 C1INH。
我们提供了 SERPING1 基因变体的功能分类，表明不同的 SERPING1 变体通过不同的、在某些情况下重叠的分子疾病机制导致致病性。对于一组基因变体，我们的数据将一些 C1INH 缺乏的遗传性血管性水肿定义为由显性负疾病机制驱动的丝氨酸蛋白酶病。
