title: Hydroquinone induces oxidative and mitochondrial damage to human retinal Müller cells (MIO-M1).
abstract: OBJECTIVE
  Smoking is a risk factor in the development of a variety of neuroretinal diseases. Therefore, we have investigated the effects of hydroquinone (HQ), a toxicant that is present in high concentrations in cigarette smoke, on a human retinal Müller cell line (MIO-M1).
  
  
  METHODS
  MIO-M1 cells were treated for 24h with four different concentrations of HQ (200μM, 100μM, 50μM, and 25μM). Assays were used to measure cell viability, reactive oxygen/nitrogen species (ROS/RNS), mitochondrial dehydrogenase activity (WST assay), caspase-3/7 activity and lactate dehydrogenase (LDH) levels. Western blot analyses with anti-LC3 and anti-GAPDH antibodies were performed on HQ-treated samples. Some cultures were treated with 4μM rapamycin, to induce autophagy, with and without the autophagy inhibitor 3-methyl-adenine (3MA), and levels of ROS/RNS and LDH were measured.
  
  
  RESULTS
  Our findings show that HQ reduced cell viability at four different concentrations tested (200, 100, 50 and 25μM); decreased mitochondrial function at concentrations of 200 and 100μM; increased ROS/RNS activity at all the concentrations tested and increased LDH levels at concentrations of 200, 100 and 50μM. Caspase-3/7 activities were not modified by HQ. However, treatment of these cells with this agent resulted in the appearance of the autophagy associated LC3-II band. Pre-treatment with 3MA reduced the ROS/RNS and LDH levels of the HQ-treated and rapamycin-treated cells.
  
  
  CONCLUSIONS
  Our study suggests that HQ damages the MIO-M1 cells through oxidative, mitochondrial and autophagic pathways and not caspase-related apoptosis.
authors.affiliation: Gavin Herbert Eye Institute, University of California, Irvine, CA, USA.
authors.forename: Claudio
authors.initials: C
authors.lastname: Ramírez
authors.forename: Khoa
authors.initials: K
authors.lastname: Pham
authors.forename: Maria Fernanda Estragó
authors.initials: MF
authors.lastname: Franco
authors.forename: Marilyn
authors.initials: M
authors.lastname: Chwa
authors.forename: Astrid
authors.initials: A
authors.lastname: Limb
authors.forename: Baruch D
authors.initials: BD
authors.lastname: Kuppermann
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Kenney
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D063928:Ependymoglial Cells / Q000187:drug effects* / Q000648:ultrastructure*; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012160:Retina / Q000166:cytology
chemical_list: D000975:Antioxidants; D006873:Hydroquinones; D017382:Reactive Oxygen Species; C025946:3-methyladenine; D007770:L-Lactate Dehydrogenase; D020169:Caspases; D000225:Adenine; C031927:hydroquinone
keywords: Apoptosis; Autophagy; Cell viability; Hydroquinone; Müller cells; Necrosis