Renal proximal tubule endocytic reabsorption pathway

The renal proximal tubule endocytic reabsorption pathway is a specialized transport system located on the apical membrane of proximal tubule cells, primarily driven by the multiligand receptors Megalin (LRP2) and Cubilin (CUBN) (Christensen & Birn, 2002). Its primary biological function is the efficient recovery of low-molecular-weight proteins, vitamins, and hormones from the glomerular filtrate to prevent their excretion and maintain systemic homeostasis (Nielsen et al., 2016). This pathway is essential for the reabsorption of vital substances such as albumin, retinol-binding protein, and vitamin D-binding protein (Schuh et al., 2018). In clinical medicine, this pathway is a double-edged sword; it is the primary route for the nephrotoxic accumulation of drugs like aminoglycosides and polymyxins, which can lead to acute kidney injury (Moestrup & Verroust, 2001). However, it also presents a significant opportunity for targeted drug delivery, where therapeutic agents are conjugated to ligands that specifically bind Megalin or Cubilin to enhance renal uptake. Dysfunction of this pathway, often due to genetic mutations or secondary damage, results in tubular proteinuria and is a key feature of conditions like Fanconi syndrome and Dent disease (Nielsen et al., 2016).

Other names

Megalin-Cubilin pathwayReceptor-mediated endocytosis in the proximal tubuleApical endocytic complexLRP2-CUBN pathway

Ligand binding to Megalin (LRP2) and Cubilin (CUBN) receptors on the apical membrane, followed by clathrin-mediated endocytosis and subsequent lysosomal degradation or transcytosis.