Mechanism of how carbamylation reduces albumin binding to FcRn contributing to increased vascular clearance.
Am J Physiol Renal Physiol
; 320(1): F114-F129, 2021 01 01.
Article
em En
| MEDLINE
| ID: mdl-33283642
ABSTRACT
Chronic kidney disease results in high serum urea concentrations leading to excessive protein carbamylation, primarily albumin. This is associated with increased cardiovascular disease and mortality. Multiple methods were used to address whether carbamylation alters albumin metabolism. Intravital two-photon imaging of the Munich Wistar Frömter (MWF) rat kidney and liver allowed us to characterize filtration and proximal tubule uptake and liver uptake. Microscale thermophoresis enabled quantification of cubilin (CUB7,8 domain) and FcRn binding. Finally, multiple biophysical methods including dynamic light scattering, small-angle X-ray scattering, LC-MS/MS and in silico analyses were used to identify the critical structural alterations and amino acid modifications of rat albumin. Carbamylation of albumin reduced binding to CUB7,8 and FcRn in a dose-dependent fashion. Carbamylation markedly increased vascular clearance of carbamylated rat serum albumin (cRSA) and altered distribution of cRSA in both the kidney and liver at 16 h post intravenous injection. By evaluating the time course of carbamylation and associated charge, size, shape, and binding parameters in combination with in silico analysis and mass spectrometry, the critical binding interaction impacting carbamylated albumin's reduced FcRn binding was identified as K524. Carbamylation of RSA had no effect on glomerular filtration or proximal tubule uptake. These data indicate urea-mediated time-dependent carbamylation of albumin lysine K524 resulted in reduced binding to CUB7,8 and FcRn that contribute to altered albumin transport, leading to increased vascular clearance and increased liver and endothelial tissue accumulation.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Albumina Sérica
/
Receptores Fc
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Antígenos de Histocompatibilidade Classe I
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Insuficiência Renal Crônica
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Túbulos Renais Proximais
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Fígado
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Am J Physiol Renal Physiol
Assunto da revista:
FISIOLOGIA
/
NEFROLOGIA
Ano de publicação:
2021
Tipo de documento:
Article