Oxidative stress increases megalin expression in the renal proximal tubules during the normoalbuminuric stage of diabetes mellitus.
Am J Physiol Renal Physiol
; 314(3): F462-F470, 2018 03 01.
Article
em En
| MEDLINE
| ID: mdl-29187367
ABSTRACT
Megalin, an endocytic receptor expressed in proximal tubule cells, plays a critical role in renal tubular protein reabsorption and is associated with the albuminuria observed in diabetic nephropathy. We have previously reported increased oxidant production in the renal cortex during the normoalbuminuric stage of diabetes mellitus (DM); however, the relationship between oxidative stress and renal megalin expression during the normoalbuminuric stage of DM remains unclear. In the present study, we evaluated whether oxidative stress affects megalin expression in the normoalbuminuric stage of DM in a streptozotocin-induced diabetic rat model and in immortalized human proximal tubular cells (HK-2). We demonstrated that increased expression of renal megalin accompanies oxidative stress during the early stage of DM, before albuminuria development. Telmisartan treatment prevented the diabetes-induced elevation in megalin level, possibly through an oxidative stress-dependent mechanism. In HK-2 cells, hydrogen peroxide significantly increased megalin levels in a dose- and time-dependent manner; however, the elevation in megalin expression was decreased following prolonged exposure to severe oxidative stress induced by 0.4 mmol/l hydrogen peroxide. High-glucose treatment also significantly increased megalin expression in HK-2 cells. Concurrent administration of the antioxidant N-acetyl-cysteine blocked the effects of high glucose on megalin expression. Furthermore, the hydrogen peroxide-induced increase in megalin expression was blocked by treatment with phosphatidylinositol 3-kinase and Akt inhibitors. Increase of phosphorylated Akt expression was also seen in the renal cortex of diabetic rats. Taken together, our results indicate that mild oxidative stress increases renal megalin expression through the phosphatidylinositol 3-kinase-Akt pathway in the normoalbuminuric stage of DM.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Estresse Oxidativo
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Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade
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Diabetes Mellitus Experimental
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Túbulos Renais Proximais
Tipo de estudo:
Prognostic_studies
Limite:
Animals
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Humans
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Male
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article