Chemical chaperones protect epidermolysis bullosa simplex keratinocytes from heat stress-induced keratin aggregation: involvement of heat shock proteins and MAP kinases

J Invest Dermatol. 2011 Aug;131(8):1684-91. doi: 10.1038/jid.2011.93. Epub 2011 Apr 14.


Epidermolysis bullosa simplex (EBS) is a blistering skin disease caused by mutations in keratin genes (KRT5 or KRT14), with no existing therapies. Aggregates of misfolded mutant keratins are seen in cultured keratinocytes from severe EBS patients. In other protein-folding disorders, involvement of molecular chaperones and the ubiquitin-proteasome system may modify disease severity. In this study, the effects of heat stress on keratin aggregation in immortalized cells from two patients with EBS (KRT5) and a healthy control were examined with and without addition of various test compounds. Heat-induced (43 °C, 30 minutes) aggregates were observed in all cell lines, the amount of which correlated with the donor phenotype. In EBS cells pre-exposed to proteasome inhibitor, MG132, and p38-mitogen-activated protein kinase (MAPK) inhibitor, SB203580, the proportion of aggregate-positive cells increased, suggesting a role of proteasomes and phosphorylation in removing mutated keratin. In contrast, aggregates were reduced by pretreatment with two chemical chaperones, trimethylamine N-oxide (TMAO) and 4-phenylbutyrate (4-PBA). TMAO also modulated stress-induced p38/c-jun N-terminal kinase (JNK) activation and expression of heat shock protein (HSPA1A), the latter of which colocalized with phosphorylated keratin 5 in EBS cells. Taken together, our findings suggest therapeutic targets for EBS and other keratinopathies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Division / physiology
  • Cell Line, Transformed
  • Cysteine Proteinase Inhibitors
  • Enzyme Inhibitors / pharmacology
  • Epidermolysis Bullosa Simplex / metabolism*
  • Epidermolysis Bullosa Simplex / pathology
  • HSP70 Heat-Shock Proteins / metabolism
  • HSP90 Heat-Shock Proteins / metabolism
  • Heat-Shock Response / physiology*
  • Hot Temperature / adverse effects
  • Humans
  • Imidazoles / pharmacology
  • JNK Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Keratin-5 / metabolism*
  • Keratinocytes / metabolism*
  • Keratinocytes / pathology
  • Leupeptins / pharmacology
  • MAP Kinase Signaling System / drug effects
  • MAP Kinase Signaling System / physiology*
  • Molecular Chaperones / metabolism*
  • Proteasome Endopeptidase Complex / metabolism
  • Proteasome Inhibitors
  • Proteostasis Deficiencies / metabolism
  • Proteostasis Deficiencies / pathology
  • Pyridines / pharmacology
  • p38 Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • p38 Mitogen-Activated Protein Kinases / metabolism


  • Cysteine Proteinase Inhibitors
  • Enzyme Inhibitors
  • HSP70 Heat-Shock Proteins
  • HSP90 Heat-Shock Proteins
  • Imidazoles
  • KRT5 protein, human
  • Keratin-5
  • Leupeptins
  • Molecular Chaperones
  • Proteasome Inhibitors
  • Pyridines
  • JNK Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Proteasome Endopeptidase Complex
  • SB 203580
  • benzyloxycarbonylleucyl-leucyl-leucine aldehyde