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Updated: May 29, 2026
Isolation of Primary Human Proximal Tubule Epithelial Cells and Their Use in Creating a Microphysiological Model of the Renal Proximal Tubule
Published on: May 9, 2025
Mouse model of proximal tubule endocytic dysfunction
Kathrin Weyer1, Tina Storm, Jingdong Shan
1Department of Biomedicine, University of Aarhus, Aarhus, Denmark.
Background:
Several studies have indicated the central role of the megalin/cubilin multiligand endocytic receptor complex in protein reabsorption in the kidney proximal tubule. However, the poor viability of the existing megalin-deficient mice precludes further studies and comparison of homogeneous groups of mice.
Methods:
Megalin- and/or cubilin-deficient mice were generated using a conditional Cre-loxP system, where the Cre gene is driven by the Wnt4 promoter. Kidney tissues from the mice were analysed for megalin and cubilin expression by quantitative reverse transcription-polymerase chain reaction, western blotting and immunohistochemistry. Renal albumin uptake was visualized by immunohistochemistry. Twenty-four-hour urine samples were collected in metabolic cages and analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and western blotting. Urinary albumin/creatinine ratios were measured by ELISA and the alkaline picrate method.
Results:
The Meg(lox/lox);Cre(+), Cubn(lox/lox);Cre(+) and Meg(lox/lox), Cubn(lox/lox);Cre(+) mice were all viable, fertile and developed normal kidneys. Megalin and/or cubilin expression, assessed by immunohistology and western blotting, was reduced by >89%. Consistent with this observation, the mice excreted megalin and cubilin ligands such as transferrin and albumin in addition to low-molecular weight proteins. We further show that megalin/cubilin double-deficient mice excrete albumin with an average of 1.45 ± 0.54 mg/day, suggesting a very low albumin concentration in the glomerular ultrafiltrate.
Conclusions:
We report here the efficient genetic ablation of megalin, cubilin or both, using a Cre transgene driven by the Wnt4 promoter. The viable megalin/cubilin double-deficient mice now allow for detailed large-scale group analysis, and we anticipate that the mice will be of great value as an animal model for proximal tubulopathies with disrupted endocytosis.
Insights
New mouse models with genetic ablation of megalin and cubilin are now available for studying kidney protein reabsorption. These viable mice enable detailed analysis of proximal tubulopathies involving disrupted endocytosis.
Area of Science:
- Nephrology
- Molecular Biology
- Genetics
Background:
- The megalin/cubilin receptor complex is crucial for protein reabsorption in kidney proximal tubules.
- Existing megalin-deficient mouse models have poor viability, limiting research.
Purpose of the Study:
- To generate viable megalin- and/or cubilin-deficient mice using a conditional Cre-loxP system.
- To establish a new animal model for studying kidney proximal tubulopathies.
Main Methods:
- Conditional Cre-loxP system with Wnt4 promoter-driven Cre.
- Analysis of megalin/cubilin expression via qRT-PCR, Western blotting, and immunohistochemistry.
- Assessment of renal albumin uptake and urinary protein excretion.
Main Results:
- Viable, fertile megalin/cubilin double-deficient mice were generated.
- Megalin and/or cubilin expression was reduced by over 89%.
- Mice exhibited increased excretion of megalin/cubilin ligands, including albumin and transferrin.
Conclusions:
- Efficient genetic ablation of megalin, cubilin, or both was achieved.
- The viable double-deficient mice allow for large-scale group analysis.
- These mice are valuable models for proximal tubulopathies with disrupted endocytosis.
