Portal de Periódicos da CAPES

Artigo Acesso aberto Produção Nacional Revisado por pares

BIBTEX RIS

Renoprotective effects of long-term low salt diet in spontaneously hypertensive rats is associated with higher renal cubilin expression

2015; Elsevier BV; Volume: 9; Issue: 4 Linguagem: Inglês

10.1016/j.jash.2015.03.192

1933-1711

Rebeca Caldeira Machado, Paula Frizera Vassallo, Marilene L. Oliveira, Daisy Motta‐Santos, Renato O. Crajoinas, Flavia L. Martins, Ludimila Forechi, Isabela Bastos Binotti, Breno Valentim Nogueira, Adriana Castello Costa Girardi, Robson A.S. Santos, José Geraldo Mill,

Sodium Intake and Health

Endocytosis of the somatostatin analogue, octreotide, by the proximal tubule-derived opossum kidney (OK) cell line.Nephrotoxicity of cancer therapy using radiolabeled somatostatin analogues such as octreotide is due to ultrafiltration and reuptake by proximal tubular cells (PTCs). The mechanism of uptake is unknown. It could occur either by receptor-mediated endocytosis via a somatostatin receptor or, alternatively, the multiligand megalin/cubilin tandem receptor, or by fluid-phase endocytosis. To define the mechanisms of internalization and to identify potential receptors, we have studied the uptake and processing of octreotide by the PTC-derived opossum kidney (OK) cell line.We compared the kinetics of uptake and fate of 111In-diethylenetriamine pentaacetic acid (DTPA)-D-Phe1-octreotide and 125I-human serum albumin (125I-HSA). To determine the contribution of receptor-mediated endocytosis, we tested competition for uptake by octreotide and somatostatin and by various megalin/cubilin ligands [receptor-associated protein (RAP), albumin, transferrin, insulin, polymixin B] or basic amino acids. The subcellular localization of fluorescein isothiocyanate (FITC)-D-Phe1-octreotide was studied by confocal microscopy.Kinetics of uptake of 111In-DTPA-D-Phe1-octreotide and 125I-HSA by OK cells were comparable, but only the somatostatin analogue was significantly retained intact. All megalin/cubilin ligands and basic amino acids strongly inhibited 125I-HSA uptake, but these could not compete for >50% of 111In-DTPA-D-Phe1-octreotide uptake. The same was found for somatostatin and octreotide. The noncompetable uptake of 111In-DTPA-D-Phe1-octreotide was comparable to the clearance of Lucifer Yellow, a marker of fluid-phase endocytosis. By confocal microscopy, FITC-D-Phe1-octreotide colocalized with transferrin in endosomes, then accumulated in lysosomes.Receptor-mediated endocytosis via megalin/cubilin and fluid-phase endocytosis contribute about equally to the uptake of radiolabeled somatostatin analogues by OK cells.