Modelling CubAm function and regulation in proximal tubular cells using iPSC-derived kidney organoids

Area of Science:

• Nephrology
• Stem Cell Biology
• Molecular Biology

Background:

• Idiopathic nephrotic syndrome (INS) involves heavy proteinuria.
• Protein reabsorption in proximal tubules relies on the megalin-cubilin-amnionless (CubAm) complex.
• Apolipoprotein A-I (ApoA-I) reabsorption is impaired in INS, but difficult to study in vitro.

Purpose of the Study:

• To develop a functional in vitro model for studying INS.
• To investigate the expression and function of the CubAm complex in kidney organoids.
• To explore the impact of protein overload on tubular cells and ApoA-I reabsorption.

Main Methods:

• Cultured RPTEC/TERT-1 cells and induced Pluripotent Stem Cells (iPSCs)-derived kidney organoids.
• Analysis of cubilin and amnionless protein expression.
• Induction of protein overload and assessment of ApoA-I targeting of cubilin.

Main Results:

• Standard cell cultures showed minimal CubAm expression.
• iPSC-derived kidney organoids exhibited robust CubAm expression.
• Protein overload increased cubilin expression, which was reversible; exogenously added ApoA-I targeted cubilin.

Conclusions:

• iPSC-derived kidney organoids serve as a valuable model for INS research.
• This model allows studying protein overload effects on tubular cells.
• The CubAm complex in kidney organoids is functional for ApoA-I endocytosis, relevant to INS pathophysiology.