Phosphorylation of Ser45 and Ser59 of αB-crystallin and p38/extracellular regulated kinase activity determine αB-crystallin-mediated protection of rat brain astrocytes from C2-ceramide- and staurosporine-induced cell death

J Neurochem. 2011 Aug;118(3):354-64. doi: 10.1111/j.1471-4159.2011.07317.x. Epub 2011 Jun 17.


We previously demonstrated that αB-crystallin and protease-activated receptor (PAR) are involved in protection of astrocytes against C2-ceramide- and staurosporine-induced cell death [Li et al. (2009) J. Neurochem.110, 1433-1444]. Here, we further investigated the mechanism of cytoprotection by αB-crystallin. Our current data revealed that after down-regulation of αB-crystallin by siRNA, cell death caused by C2-ceramide and staurosporine is increased. Furthermore, we investigated the mechanism of cytoprotection of astrocytes by intracellular αB-crystallin. Application of specific inhibitors of p38 and extracellular regulated kinase (ERK) abrogates the protection of astrocytes by over-expression of αB-crystallin. Thus, p38 and ERK contribute to protective processes by αB-crystallin. To reveal the molecular mechanism of αB-crystallin-mediated cytoprotection, we mimicked phosphorylation or unphosphorylation of αB-crystallin. In these experiments, we found that the phosphorylation of αB-crystallin at Ser45 and Ser59 is required for protection. Ser19 phosphorylation of αB-crystallin does not contribute to protection. Moreover, we detected that PAR-2 activation increases the phosphorylation level of αB-crystallin at Ser59, but does not affect the expression level of αB-crystallin. Thus, endogenous αB-crystallin has protective capacity employing a mechanism, which involves regulation of the phosphorylation status of αB-crystallin and p38 and ERK activity. Moreover, we report that PAR-2 activation evokes the phosphorylation of αB-crystallin to increase astrocytes survival.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / drug effects*
  • Blotting, Western
  • Cell Death / drug effects
  • Cell Survival / drug effects
  • Cells, Cultured
  • Down-Regulation / drug effects
  • Extracellular Signal-Regulated MAP Kinases / physiology
  • JNK Mitogen-Activated Protein Kinases / physiology
  • Neuroprotective Agents*
  • Phosphorylation
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics
  • Rats
  • Receptor, PAR-2 / genetics
  • Receptor, PAR-2 / physiology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Serine / chemistry*
  • Sphingosine / analogs & derivatives*
  • Sphingosine / antagonists & inhibitors
  • Sphingosine / toxicity
  • Staurosporine / antagonists & inhibitors*
  • Staurosporine / toxicity*
  • alpha-Crystallin B Chain / chemistry
  • alpha-Crystallin B Chain / physiology*
  • p38 Mitogen-Activated Protein Kinases / chemistry
  • p38 Mitogen-Activated Protein Kinases / physiology*


  • N-acetylsphingosine
  • Neuroprotective Agents
  • RNA, Messenger
  • Receptor, PAR-2
  • alpha-Crystallin B Chain
  • Serine
  • Extracellular Signal-Regulated MAP Kinases
  • JNK Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Staurosporine
  • Sphingosine