Cigarette smoke-related hydroquinone induces filamentous actin reorganization and heat shock protein 27 phosphorylation through p38 and extracellular signal-regulated kinase 1/2 in retinal pigment epithelium: implications for age-related macular degeneration

Am J Pathol. 2010 Sep;177(3):1198-213. doi: 10.2353/ajpath.2010.091108. Epub 2010 Jul 22.

Abstract

Retinal pigment epithelium (RPE)-derived membranous debris named blebs, may accumulate and contribute to sub-RPE deposit formation, which is the earliest sign of age-related macular degeneration (AMD). Oxidative injury to the RPE might play a significant role in AMD. However, the underlying mechanisms are unknown. We previously reported that hydroquinone (HQ), a major pro-oxidant in cigarette smoke, foodstuff, and atmospheric pollutants, induces actin rearrangement and membrane blebbing in RPE cells as well as sub-RPE deposits in mice. Here, we show for the first time that phosphorylated Heat shock protein 27 (Hsp27), a key regulator of actin filaments dynamics, is up-regulated in RPE from patients with AMD. Also, HQ-induced nonlethal oxidative injury led to Hsp27mRNA up-regulation, dimer formation, and Hsp27 phosphorylation in ARPE-19 cells. Furthermore, we found that a cross talk between p38 and extracellular signal-regulated kinase (ERK) mediates HQ-induced Hsp27 phosphorylation and actin aggregate formation, revealing ERK as a novel upstream mediator of Hsp27 phosphorylation. Finally, we demonstrated that Hsp25, p38, and ERK phosphorylation are increased in aging C57BL/6 mice chronically exposed to HQ, whereas Hsp25 expression is decreased. Our data suggest that phosphorylated Hsp27 might be a key mediator in AMD and HQ-induced oxidative injury to the RPE, which may provide helpful insights into the early cellular events associated with actin reorganization and bleb formation involved in sub-RPE deposits formation relevant to the pathogenesis of AMD.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Actins / metabolism*
  • Aged
  • Aged, 80 and over
  • Analysis of Variance
  • Animals
  • Blotting, Western
  • Cells, Cultured
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Female
  • Fluorescent Antibody Technique
  • HSP27 Heat-Shock Proteins / metabolism*
  • Humans
  • Hydroquinones / pharmacology*
  • Macular Degeneration / metabolism*
  • Macular Degeneration / pathology
  • Male
  • Mice
  • Middle Aged
  • Phosphorylation / drug effects*
  • Retinal Pigment Epithelium / drug effects*
  • Retinal Pigment Epithelium / metabolism*
  • Retinal Pigment Epithelium / pathology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Smoking
  • Statistics, Nonparametric
  • p38 Mitogen-Activated Protein Kinases / metabolism*

Substances

  • Actins
  • HSP27 Heat-Shock Proteins
  • Hydroquinones
  • Extracellular Signal-Regulated MAP Kinases
  • p38 Mitogen-Activated Protein Kinases
  • hydroquinone