Siegerist Florian, Hay Eleonora, Hammer Elke, Iervolino Anna, Weber Claudia, Dikou Juan Saydou, Stamellou Eleni, Butt Linus, Benzing Thomas, Wiech Thorsten, Brinkötter Paul T, Zimmerman Uwe, Capasso Giovambattista, Chatziantoniou Christos, Chadjichristos Christos E, Huber Tobias B, Völker Uwe, Schindler Maximilian, Endlich Nicole
Institute for Anatomy and Cell Biology, University Medicine Greifswald, Friedrich-Loeffler-Str. 23C, 17479, Greifswald, Germany.
Neonatology and Pediatric Intensive Care Medicine, Department of Pediatrics and Adolescent Medicine, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße, 17475, Greifswald, Germany.
J Transl Med. 2025 Jun 25;23(1):701. doi: 10.1186/s12967-025-06696-9.
Podocyte dysfunction is central to various glomerular diseases, necessitating reliable biomarkers for early detection and diagnosis. This study investigates the regulatory mechanisms of membrane-associated guanylate kinase inverted 2 (MAGI2) and its potential as a biomarker for podocytopathies.
Using fluorescence confocal laser scanning microscopy and super-resolution structured illumination microscopy of immunostained tissue sections of murine, human, and zebrafish tissue we investigated the subcellular location of MAGI2 in the kidney. We assessed the differential regulation of MAGI2 in glomerular disease animal models, and isolated glomerular dedifferentiation using immunostainings and LC-MS/MS tandem mass spectrometry. With CRISPR-Cas9, we generated zebrafish F0 generation mutants lacking either the zebrafish orthologue magi2a or nphs1.
The expression of the gene coding for the scaffolding protein MAGI2 was examined across four species and demonstrated to be conserved within the podocyte filtration slit. In vitro and in vivo studies using isolated glomeruli and mammalian animal models of glomerular disease, including DOCA-salt hypertension, nephrotoxic serum nephritis, and puromycin aminonucleoside nephropathy, demonstrated significant downregulation of MAGI2 in injured podocytes. This downregulation was also conserved in a zebrafish model of focal and segmental glomerulosclerosis (FSGS), and the podocyte-specific MAGI2 ortholog Magi2a was reduced post podocyte injury. CRISPR/Cas9-generated zebrafish mutants for magi2a exhibited marked glomerular filtration barrier defects and downregulation of nephrin, underscoring MAGI2's critical role in podocyte function. Human biopsy analyses revealed differential MAGI2 expression: it was increased in minimal change disease (MCD) patients but significantly decreased in primary, but not secondary FSGS cases. As MAGI2 localization did not change in disease states it is an alternative marker for super-resolution microscopy-based morphometry of the filtration slit, correlating with nephrin-based measurements.
These findings highlight the potential of MAGI2 as a sensitive biomarker for podocyte injury and its diagnostic utility as a molecular discriminator in differentiating between primary FSGS and MCD in kidney biopsies.
足细胞功能障碍是各种肾小球疾病的核心问题，因此需要可靠的生物标志物用于早期检测和诊断。本研究探讨了膜相关鸟苷酸激酶反向2（MAGI2）的调控机制及其作为足细胞病生物标志物的潜力。
利用荧光共聚焦激光扫描显微镜和超分辨率结构光照显微镜对小鼠、人类和斑马鱼组织的免疫染色组织切片进行研究，我们调查了MAGI2在肾脏中的亚细胞定位。我们评估了MAGI2在肾小球疾病动物模型中的差异调节，并通过免疫染色和液相色谱-串联质谱联用技术分离肾小球去分化。利用CRISPR-Cas9技术，我们构建了斑马鱼F0代突变体，缺失斑马鱼同源基因magi2a或nphs1。
对编码支架蛋白MAGI2的基因表达在四个物种中进行了检测，结果表明其在足细胞滤过裂隙中保守。使用分离的肾小球和肾小球疾病的哺乳动物动物模型进行的体外和体内研究，包括去氧皮质酮-盐高血压、肾毒性血清肾炎和嘌呤霉素氨基核苷肾病，均显示损伤的足细胞中MAGI2显著下调。这种下调在局灶节段性肾小球硬化（FSGS）的斑马鱼模型中也存在，足细胞特异性MAGI2同源基因Magi2a在足细胞损伤后减少。CRISPR/Cas9构建的magi2a斑马鱼突变体表现出明显的肾小球滤过屏障缺陷和nephrin下调，突出了MAGI2在足细胞功能中的关键作用。人类活检分析显示MAGI2表达存在差异：在微小病变病（MCD）患者中升高，但在原发性FSGS病例中显著降低，而在继发性FSGS病例中未降低。由于MAGI2在疾病状态下的定位没有变化，它是基于超分辨率显微镜的滤过裂隙形态测量的替代标志物，与基于nephrin的测量相关。
这些发现突出了MAGI2作为足细胞损伤敏感生物标志物的潜力及其在肾脏活检中区分原发性FSGS和MCD的分子鉴别诊断中的应用价值。
