Distal renal tubules are deficient in aggresome formation and autophagy upon aldosterone administration

PLoS One. 2014 Jul 7;9(7):e101258. doi: 10.1371/journal.pone.0101258. eCollection 2014.

Abstract

Prolonged elevations of plasma aldosterone levels are associated with renal pathogenesis. We hypothesized that renal distress could be imposed by an augmented aldosterone-induced protein turnover challenging cellular protein degradation systems of the renal tubular cells. Cellular accumulation of specific protein aggregates in rat kidneys was assessed after 7 days of aldosterone administration. Aldosterone induced intracellular accumulation of 60 s ribosomal protein L22 in protein aggregates, specifically in the distal convoluted tubules. The mineralocorticoid receptor inhibitor spironolactone abolished aldosterone-induced accumulation of these aggregates. The aldosterone-induced protein aggregates also contained proteasome 20 s subunits. The partial de-ubiquitinase ataxin-3 was not localized to the distal renal tubule protein aggregates, and the aggregates only modestly colocalized with aggresome transfer proteins dynactin p62 and histone deacetylase 6. Intracellular protein aggregation in distal renal tubules did not lead to development of classical juxta-nuclear aggresomes or to autophagosome formation. Finally, aldosterone treatment induced foci in renal cortex of epithelial vimentin expression and a loss of E-cadherin expression, as signs of cellular stress. The cellular changes occurred within high, but physiological aldosterone concentrations. We conclude that aldosterone induces protein accumulation in distal renal tubules; these aggregates are not cleared by autophagy that may lead to early renal tubular damage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldosterone / administration & dosage*
  • Aldosterone / pharmacology*
  • Animals
  • Autophagy / drug effects*
  • Calcium Channels / metabolism
  • Cytosol / drug effects
  • Cytosol / metabolism
  • Gene Expression Regulation / drug effects
  • Histone Deacetylases / metabolism
  • Kidney Tubules, Distal / cytology*
  • Kidney Tubules, Distal / drug effects
  • Kidney Tubules, Distal / immunology*
  • Lymphocytes / drug effects
  • Lymphocytes / immunology
  • Male
  • Microtubules / drug effects*
  • Microtubules / metabolism*
  • Proteasome Endopeptidase Complex / metabolism
  • Protein Aggregates / drug effects
  • Protein Transport / drug effects
  • Proteolysis / drug effects
  • Rats
  • Rats, Wistar
  • Ribosome Subunits, Large, Eukaryotic / metabolism
  • Vimentin / metabolism

Substances

  • Calcium Channels
  • Protein Aggregates
  • Vimentin
  • Aldosterone
  • Proteasome Endopeptidase Complex
  • Histone Deacetylases

Grants and funding

Muhammad Umar Cheema was supported by a PhD stipend co-financed by Graduate School of Health Sciences, Aarhus University and the Water and Salt Research Center at Aarhus University (established and supported by the Danish National Research Foundation). Financial support for running costs were granted by the Lundbeck Foundation and the Danish Heart Association. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.