Cell and Tissue Research

, Volume 352, Issue 3, pp 427–443

Astrocyte plasticity revealed by adaptations to severe proteotoxic stress

  • Amanda M. Titler
  • Jessica M. Posimo
  • Rehana K. Leak
Regular Article

DOI: 10.1007/s00441-013-1571-4

Cite this article as:
Titler, A.M., Posimo, J.M. & Leak, R.K. Cell Tissue Res (2013) 352: 427. doi:10.1007/s00441-013-1571-4

Abstract

Neurodegeneration is characterized by an accumulation of misfolded proteins in neurons. It is less well appreciated that glia often also accumulate misfolded proteins. However, glia are highly plastic and may adapt to stress readily. Endogenous adaptations to stress can be measured by challenging stressed cells with a second hit and then measuring viability. For example, subtoxic stress can elicit preconditioning or tolerance against second hits. However, it is not known if severe stress that kills half the population can elicit endogenous adaptations in the remaining survivors. Glia, with their resilient nature, offer an ideal model in which to test this new hypothesis. The present study is the first demonstration that astrocytes surviving one LC50 hit of the proteasome inhibitor MG132 were protected against a second MG132 hit. ATP loss in response to the second hit was also prevented. MG132 caused compensatory rises in stress-sensitive heat shock proteins. However, stressed astrocytes exhibited an even greater rise in ubiquitin-conjugated proteins upon the second hit, illustrating the severity of the proteotoxicity and verifying the continued impact of MG132. Despite this stress, MG132-pretreated astrocytes were completely prevented from losing glutathione with the second hit. Furthermore, inhibiting glutathione synthesis rendered astrocytes sensitive to the second hit, unmasking the cumulative impact of two hits by removal of an endogenous adaptation. These findings suggest that stressed astrocytes become progressively harder to kill by virtue of antioxidant defenses. Such plasticity may permit astrocytes under severe stress to better support neurons and help explain the protracted nature of neurodegeneration.

Keywords

Two hit Dual hit Neurodegeneration Glia Toxic stress Preconditioning Hormesis Rat (Sprague Dawley) 

Abbreviations

BSO

Buthionine sulfoximine

DMSO

Dimethyl sulfoxide

GFAP

Glial fibrillary acidic protein

Hsp70

Heat shock protein 70

LC50

Lethal concentration to 50% of cells

LAMP2a

Lysosome-associated membrane protein type 2a

PBS

Phosphate-buffered saline

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Amanda M. Titler
    • 1
  • Jessica M. Posimo
    • 1
  • Rehana K. Leak
    • 1
  1. 1.Division of Pharmaceutical Sciences, Mylan School of PharmacyDuquesne UniversityPittsburghUSA

Personalised recommendations