背景:HOIP是E3连接酶复合物(线性泛素链组装复合物)的催化亚基,能够产生线性泛素链。然而,罕见的HOIP功能缺陷变异体的作用尚不清楚.其致病机制及其与免疫缺陷表型的关系仍有待阐明。
方法:基于270个基因的下一代测序小组,我们确定了导致常见变异型免疫缺陷性疾病的HOIP缺失变异.进行了生物信息学分析和基于细胞的实验以研究变体引起免疫缺陷疾病的分子机制。
结果:鉴定了HOIP中的纯合功能丧失变体。该变体导致移码并在信使RNA中产生过早终止密码子,导致C端截短的HOIP突变体,也就是说,线性泛素链特异性催化结构域的丢失。截短的HOIP突变体在线性泛素化中具有受损的E3连接酶功能,导致经典NF-κB信号传导的抑制和增加TNF诱导的多种形式的细胞死亡。
结论:功能丧失型HOIP变异是免疫缺陷的原因。典型的NF-κB通路和细胞死亡参与了疾病的发病机理。
背景:本研究由国家自然科学基金(编号:82270444和81501851)。
背景:这项研究之前的证据LUBAC是唯一已知的线性泛素链组装复合物,其中HOIP是必需的催化亚基。现在已经在两名免疫缺陷患者中鉴定出三种HOIP变体并进行功能表征。然而,目前还没有关于仅催化结构域缺失变体在人类中的致病性的报道,或催化结构域缺失变体的致病机制。本研究的附加值我们报告了导致HOIP催化结构域缺失的常染色体隐性纯合缺失变体的第一例。我们证明了该变体是使用异源表达系统的功能丧失变体。该变体具有受损的E3连接酶功能。它仍然可以与LUBAC的其他亚基结合,但它不能产生线性泛素链。我们还探讨了这种变异导致免疫缺陷的潜在机制。该变体减弱了典型的NF-κB和MAPK信号级联,并增加了TNFα诱导的多种细胞死亡和线粒体凋亡途径激活的敏感性。这些发现为HOIP和相关信号通路中先天性免疫错误的患者的治疗和药物开发提供了支持。所有现有证据的含义首先,本研究扩展了HOIP致病变异数据库和表型谱.此外,对致病变异与NF-κB信号通路和细胞死亡相关的生物学功能的研究提供了对HOIP缺陷性免疫性疾病的遗传基础和发病机理的新认识,表明HOIP和相关信号通路变异作为相似遗传缺陷表型患者诊断目标的必要性。.
BACKGROUND: HOIP is the catalytic subunit of the E3 ligase complex (linear ubiquitin chain assembly complex), which is able to generate linear ubiquitin chains. However, the role of rare HOIP functionally deficient variants remains unclear. The pathogenic mechanism and the relationship with immune deficiency phenotypes remain to be clarified.
METHODS: Based on a next-generation sequencing panel of 270 genes, we identified a HOIP deletion variant that causes common variable immunodeficiency disease. Bioinformatics analysis and cell-based experiments were performed to study the molecular mechanism by which the variant causes immunodeficiency diseases.
RESULTS: A homozygous loss-of-function variant in HOIP was identified. The variant causes a frameshift and generates a premature termination codon in messenger RNA, resulting in a C-terminal truncated HOIP mutant, that is, the loss of the linear ubiquitin chain-specific catalytic domain. The truncated HOIP mutant has impaired E3 ligase function in linear ubiquitination, leading to the suppression of canonical NF-κB signalling and increased TNF-induced multiple forms of cell death.
CONCLUSIONS: The loss-of-function HOIP variant accounts for the immune deficiencies. The canonical NF-κB pathway and cell death are involved in the pathogenesis of the disease.
BACKGROUND: This study was funded by the National Natural Science Foundation of China (No. 82270444 and 81501851).
BACKGROUND: Evidence before this study LUBAC is the only known linear ubiquitin chain assembly complex for which HOIP is an essential catalytic subunit. Three HOIP variants have now been identified in two immunodeficient patients and functionally characterised. However, there have been no reports on the pathogenicity of only catalytic domain deletion variants in humans, or the pathogenic mechanisms of catalytic domain deletion variants. Added value of this study We report the first case of an autosomal recessive homozygous deletion variant that results in deletion of the HOIP catalytic structural domain. We demonstrate that this variant is a loss-of-function variant using a heterologous expression system. The variant has impaired E3 ligase function. It can still bind to other subunits of LUBAC, but it fails to generate linear ubiquitin chains. We also explored the underlying mechanisms by which this variant leads to immunodeficiency. The variant attenuates the canonical NF-κB and MAPK signalling cascades and increases the sensitivity of TNFα-induced diverse cell death and activation of mitochondrial apoptosis pathways. These findings provide support for the treatment and drug development of patients with inborn errors of immunity in HOIP and related signalling pathways. Implications of all the available evidence First, this study expands the HOIP pathogenic variant database and phenotypic spectrum. Furthermore, studies on the biological functions of pathogenic variants in relation to the NF-κB signalling pathway and cell death provided new understanding into the genetic basis and pathogenesis of HOIP-deficient immune disease, indicating the necessity of HOIP and related signalling pathway variants as diagnostic targets in patients with similar genetic deficiency phenotypes..