Gélinas Roselle, Lévesque Chloé, Thompson Legault Julie, Rivard Marie-Eve, Villeneuve Louis, Laprise Catherine, Rioux John D
Montreal Heart Institute, Montreal, QC, Canada.
Université du Québec à Chicoutimi, Saguenay, QC, Canada.
Front Genet. 2024 Apr 19;15:1375467. doi: 10.3389/fgene.2024.1375467. eCollection 2024.
Leigh syndrome French Canadian type (LSFC) is a recessive neurodegenerative disease characterized by tissue-specific deficiency in cytochrome c oxidase (COX), the fourth complex in the oxidative phosphorylation system. LSFC is caused by mutations in the leucine rich pentatricopeptide repeat containing gene (). Most LSFC patients in Quebec are homozygous for an A354V substitution that causes a decrease in the expression of the LRPPRC protein. While LRPPRC is ubiquitously expressed and is involved in multiple cellular functions, tissue-specific expression of LRPPRC and COX activity is correlated with clinical features. In this proof-of-principle study, we developed human induced pluripotent stem cell (hiPSC)-based models from fibroblasts taken from a patient with LSFC, homozygous for the *354V allele, and from a control, homozygous for the *A354 allele. Specifically, for both of these fibroblast lines we generated hiPSC, hiPSC-derived cardiomyocytes (hiPSC-CMs) and hepatocyte-like cell (hiPSC-HLCs) lines, as well as the three germ layers. We observed that LRPPRC protein expression is reduced in all cell lines/layers derived from LSFC patient compared to control cells, with a reduction ranging from ∼70% in hiPSC-CMs to undetectable levels in hiPSC-HLC, reflecting tissue heterogeneity observed in patient tissues. We next performed exploratory analyses of these cell lines and observed that COX protein expression was reduced in all cell lines derived from LSFC patient compared to control cells. We also observed that mutant LRPPRC was associated with altered expression of key markers of endoplasmic reticulum stress response in hiPSC-HLCs but not in other cell types that were tested. While this demonstrates feasibility of the approach to experimentally study genotype-based differences that have tissue-specific impacts, this study will need to be extended to a larger number of patients and controls to not only validate the current observations but also to delve more deeply in the pathogenic mechanisms of LSFC.
法裔加拿大人型 Leigh 综合征（LSFC）是一种隐性神经退行性疾病，其特征是细胞色素 c 氧化酶（COX）存在组织特异性缺陷，COX 是氧化磷酸化系统中的第四个复合体。LSFC 由富含亮氨酸的五肽重复序列基因（）中的突变引起。魁北克的大多数 LSFC 患者对于导致 LRPPRC 蛋白表达降低的 A354V 替代是纯合的。虽然 LRPPRC 在全身广泛表达并参与多种细胞功能，但 LRPPRC 的组织特异性表达和 COX 活性与临床特征相关。在这项原理验证研究中，我们从一名 LSFC 患者（*354V 等位基因纯合）的成纤维细胞以及一名对照（*A354 等位基因纯合）的成纤维细胞中建立了基于人类诱导多能干细胞（hiPSC）的模型。具体而言，对于这两种成纤维细胞系，我们分别生成了 hiPSC、hiPSC 衍生的心肌细胞（hiPSC-CMs）和肝样细胞（hiPSC-HLCs）系，以及三个胚层。我们观察到，与对照细胞相比，来自 LSFC 患者的所有细胞系/层中的 LRPPRC 蛋白表达均降低，降低幅度从 hiPSC-CMs 中的约 70%到 hiPSC-HLC 中无法检测到，这反映了在患者组织中观察到的组织异质性。接下来，我们对这些细胞系进行了探索性分析，观察到与对照细胞相比，来自 LSFC 患者的所有细胞系中的 COX 蛋白表达均降低。我们还观察到，突变型 LRPPRC 与 hiPSC-HLCs 中内质网应激反应关键标志物的表达改变有关，但在其他测试的细胞类型中未观察到。虽然这证明了通过实验研究具有组织特异性影响的基于基因型差异的方法的可行性，但这项研究需要扩展到更多的患者和对照，不仅要验证当前的观察结果，还要更深入地探究 LSFC 的致病机制。
