Gürses Cila Hacer Esra, Dursun Ali, Vardar Acar Neşe, Geçici Neslihan Nisa, Ayhan Selda, Oskay Halaçlı Sevil, Özgül R Köksal
Institute of Child Health, Department of Pediatric Metabolism, Faculty of Medicine, Hacettepe University, Ankara, Türkiye.
Hacettepe University, School of Medicine, Ankara, Türkiye.
Mol Biol Rep. 2025 Jun 16;52(1):597. doi: 10.1007/s11033-025-10681-2.
Phenylketonuria (PKU) is an inherited metabolic disease of amino acid metabolism characterized by the deficiency of activity in phenylalanine (Phe) hydroxylase enzyme, leading to the accumulation of Phe and its metabolites in the blood and tissues of affected patients. PKU, caused by various mutations leading to misfolded or nonfunctional proteins in the cells, still has an incompletely understood pathophysiology. This study aims to investigate the role of endoplasmic reticulum (ER) stress and ER stress response in PKU pathophysiology.
Peripheral blood mononuclear cells (PBMCs) isolated from PKU patients carrying distinct protein misfolding mutations were analyzed to investigate the involvement of ER stress-related gene expression and cell death pathways. A comprehensive evaluation was conducted using quantitative real-time PCR and flow cytometry under both physiological (basal) conditions and following Phe administration, with the aim of elucidating the molecular mechanisms underlying Phe-induced cellular stress. Our results demonstrates that PKU patients exhibit a response to ER stress mediated by the IRE1 and ATF6 pathways of the UPR. We also observe disruptions in autophagic flux, as shown by the expression results of LC3B and p62 proteins. Importantly, the PBMCs do not appear to undergo immediate apoptotic cell death. The avoidance of apoptosis induction, even in the context of acute Phe treatment in the PBMCs of PKU patients who have been chronically exposed to ER stress, indicates an adaptive mechanism that facilitates cellular survival in these patients.
By focusing on the ER stress response in PKU patients with different type of mutations leading to protein misfolding, this study has the potential to provide new insights into PKU pathophysiology.
苯丙酮尿症（PKU）是一种氨基酸代谢的遗传性代谢疾病，其特征是苯丙氨酸（Phe）羟化酶活性缺乏，导致受影响患者的血液和组织中Phe及其代谢产物积累。PKU由各种导致细胞内蛋白质错误折叠或无功能的突变引起，其病理生理学仍未完全了解。本研究旨在探讨内质网（ER）应激和ER应激反应在PKU病理生理学中的作用。
分析从携带不同蛋白质错误折叠突变的PKU患者中分离出的外周血单核细胞（PBMC），以研究ER应激相关基因表达和细胞死亡途径的参与情况。在生理（基础）条件和给予Phe后，使用定量实时PCR和流式细胞术进行综合评估，以阐明Phe诱导细胞应激的分子机制。我们的结果表明，PKU患者表现出对由未折叠蛋白反应（UPR）的IRE1和ATF6途径介导的ER应激的反应。我们还观察到自噬通量的破坏，如LC3B和p62蛋白的表达结果所示。重要的是，PBMC似乎不会立即发生凋亡性细胞死亡。即使在长期暴露于ER应激的PKU患者的PBMC中进行急性Phe治疗的情况下，避免凋亡诱导表明存在一种促进这些患者细胞存活的适应性机制。
通过关注不同类型导致蛋白质错误折叠的突变的PKU患者的ER应激反应，本研究有可能为PKU病理生理学提供新的见解。
