title: Glutathione--linking cell proliferation to oxidative stress.
abstract: CONCLUSIONS
  The multifaceted functions of reduced glutathione (gamma-glutamyl-cysteinyl-glycine; GSH) continue to fascinate plants and animal scientists, not least because of the dynamic relationships between GSH and reactive oxygen species (ROS) that underpin reduction/oxidation (redox) regulation and signalling. Here we consider the respective roles of ROS and GSH in the regulation of plant growth, with a particular focus on regulation of the plant cell cycle. Glutathione is discussed not only as a crucial low molecular weight redox buffer that shields nuclear processes against oxidative challenge but also a flexible regulator of genetic and epigenetic functions.
  
  
  BACKGROUND
  The intracellular compartmentalization of GSH during the cell cycle is remarkably consistent in plants and animals. Moreover, measurements of in vivo glutathione redox potentials reveal that the cellular environment is much more reducing than predicted from GSH/GSSG ratios measured in tissue extracts. The redox potential of the cytosol and nuclei of non-dividing plant cells is about -300 mV. This relatively low redox potential maintained even in cells experiencing oxidative stress by a number of mechanisms including vacuolar sequestration of GSSG. We propose that regulated ROS production linked to glutathione-mediated signalling events are the hallmark of viable cells within a changing and challenging environment.
  
  
  RESULTS
  The concept that the cell cycle in animals is subject to redox controls is well established but little is known about how ROS and GSH regulate this process in plants. However, it is increasingly likely that redox controls exist in plants, although possibly through different pathways. Moreover, redox-regulated proteins that function in cell cycle checkpoints remain to be identified in plants. While GSH-responsive genes have now been identified, the mechanisms that mediate and regulate protein glutathionylation in plants remain poorly defined.
  
  
  CONCLUSIONS
  The nuclear GSH pool provides an appropriate redox environment for essential nuclear functions. Future work will focus on how this essential thiol interacts with the nuclear thioredoxin system and nitric oxide to regulate genetic and epigenetic mechanisms. The characterization of redox-regulated cell cycle proteins in plants, and the elucidation of mechanisms that facilitate GSH accumulation in the nucleus are keep steps to unravelling the complexities of nuclear redox controls.
authors.affiliation: CEBAS-CSIC, Department of Plant Breeding, P.O. Box 164, Campus de Espinardo, 30100 Murcia, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Diaz-Vivancos
authors.affiliation: Centre for Plant Sciences, Faculty of Biology, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Ambra
authors.initials: A
authors.lastname: de Simone
authors.affiliation: Lumora Ltd, Bartholomews Walk, Cambridge Business Park, Cambridge CB7 4EA, UK.
authors.forename: Guy
authors.initials: G
authors.lastname: Kiddle
authors.affiliation: Centre for Plant Sciences, Faculty of Biology, University of Leeds, Leeds LS2 9JT, UK. Electronic address: c.foyer@leeds.ac.uk.
authors.forename: Christine H
authors.initials: CH
authors.lastname: Foyer
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D010084:Oxidation-Reduction; D018384:Oxidative Stress
chemical_list: D005978:Glutathione
keywords: Cell cycle; Epigenetics; Glutathione; Nucleus; Oxidative stress; Plant growth and development; Reactive oxygen species