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. 2023 Sep 1;18(9):1222-1224.
doi: 10.2215/CJN.0000000000000153. Epub 2023 Mar 21.

Is Albumin Toxic to the Kidney?: It Depends

Bruce A Molitoris  1 , Mark C Wagner
Affiliations

Is Albumin Toxic to the Kidney?: It Depends

Bruce A Molitoris et al. Clin J Am Soc Nephrol. .
No abstract available

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Figures

Figure 1
Figure 1
Albumin uptake and processing by the proximal tubule. (A) Albumin filtered across the glomerulus into Bowman's space is reabsorbed by both receptor-mediated endocytosis of clathrin-coated vesicles, mediated by binding to the apical megalin-cubilin receptor, and fluid-phase endocytosis or clathrin-independent endocytosis. After uptake, albumin can be transcytosed, mediated by dissociation from the megalin-cubilin complex and subsequent binding to the neonatal Fc receptor (FcRn) in the acidic endosomal environment, or undergo catabolism by lysosomal trafficking and degradation (nonbinding FcRn albumin). Albumin fragments in the urine result from lysosomal exocytosis of partially degraded albumin or peptide hydrolysis by apical membrane proteases. (B) An intravital two-photon image of an S1 proximal tubule section after infusion of Texas Red-X-rat serum albumin. The inset at the bottom right in the panel shows the S1 segment in a pseudocolor palette to better discern dimmer intensities not readily evident in the black-and-white version. The image, obtained 100 seconds after the start of intravenous albumin infusion, clearly shows small, distinct, early endocytic vesicles lining the subapical region, with a few appearing to have traversed well into the cytosol of the tubular epithelium. (C) Albumin structure (PDB ID 1E78) labeled for many of its various binding moieties and modifications, including carbamylation, glycation, fatty acid, and oxidation. The primary site of both glycation and carbamylation is K525 (blue), whereas R410 is a non-lysine glycated site, and C34 is the oxidation site. Other sites are noted to emphasize the potential effect of modifications/associations on albumin's many interactions. This figure was modified from ref. , with permission. CIE, clathrin-independent endocytosis; CME, clathrin-mediated endocytosis.
See this image and copyright information in PMC

References

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