Figure 1.

The role of proximal tubular reabsorption in normal and proteinuric conditions. On the left, normal filtration and reabsorption of proteins, protein-bound lipids and toxins (such as drugs) is depicted. Protein and lipid catabolism in lysosomes and mitochondria is important to meet energy demands of PTC. In glomerular diseases, such as nephrotic syndrome or diabetic nephropathy (DN), PTC are exposed to protein, lipid and toxin overload (middle). Particularly, saturated fatty acids bound to albumin are known to cause cell damage through endoplasmic reticulum stress. Damage may be prevented by reducing PTC uptake, e.g. in patients with CUBN/AMN mutations (right).