Proximal Tubule Mechanisms in Kidney Disease

The renal proximal tubule performs the bulk of solute and protein reabsorption after glomerular filtration, maintaining fluid and electrolyte homeostasis while preventing proteinuria. Its epithelial cells engage in high‐capacity receptor-mediated endocytosis through multiligand receptors such as megalin and cubilin to reclaim filtered albumin, low-molecular-weight proteins and carrier-bound nutrients. Intracellular trafficking, lysosomal processing and proteasomal degradation within proximal tubular cells finely regulate receptor recycling and signalling. Perturbations of these processes—whether by genetic variation, toxic injury or metabolic stress—lead to maladaptive responses including tubular cell apoptosis, inflammasome activation, interstitial inflammation and progressive fibrosis. Cumulative tubular injury underlies acute kidney injury and chronic kidney disease progression, and highlights the proximal tubule as both a victim and driver of renal pathology. Elucidation of molecular pathways governing tubular reabsorption, receptor turnover and cell fate decisions has therefore become central to the development of targeted therapies aimed at preserving tubular integrity and halting disease progression.

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Proximal Tubule Mechanisms in Kidney Disease publication trend

The graph below shows the total number of articles in proximal tubule mechanisms in kidney disease across all publications each year (not limited to Nature Index journals).

Technical terms

Proximal tubule: the initial segment of the renal tubule responsible for reabsorbing the majority of filtered solutes and proteins.

Megalin: a large multiligand endocytic receptor expressed on the apical membrane of proximal tubular cells that mediates protein and vitamin uptake.

Cubilin: an endocytic co-receptor that partners with megalin to internalise filtered proteins and micronutrients.

Endocytosis: the cellular process of internalising extracellular molecules via receptor-mediated vesicle formation.

Proteinuria: the presence of excess protein in the urine, reflecting impaired glomerular filtration or diminished tubular reabsorption.

Inflammasome: a multiprotein complex, such as NLRP3, that activates inflammatory cytokines in response to cellular stress.

Proteasome: a cytosolic protein complex responsible for degradation of ubiquitin-tagged proteins, regulating receptor levels and apoptotic signals.

References

1. Chloroquine Intervenes Nephrotoxicity of Nilotinib through Deubiquitinase USP13‐Mediated Stabilization of Bcl‐XL. Advanced Science (2023).
2. Megalin. Journal of the American Society of Nephrology (2024).