title: Oxidative stress promotes autophagic cell death in human neuroblastoma cells with ectopic transfer of mitochondrial PPP2R2B (Bbeta2).
abstract: BACKGROUND
  The multifunctional protein phosphatase 2A (PP2A) is a heterotrimeric serine/threonine protein phosphatase composed of a scaffolding, catalytic and regulatory subunits. By modifying various downstream signal transducers, the aberrant expression of the brain-targeted regulatory subunit PPP2R2B is associated with the onset of a panel of neuronal disorders. The alternatively splicing of PPP2R2B encodes two regulatory subunit isoforms that determine cellular distribution of the neuron-specific holoenzyme to mitochondria (Bbeta2) and cytoplasm (Bbeta1), respectively.
  
  
  RESULTS
  Human neuroblastoma cells were transfected with PPP2R2B constructs encoding the complete sequences of Bbeta2 and Bbeta1, respectively. The colonies with antibiotic resistance were selected as stable cell lines. Both ectopic Bbeta1 and Bbeta2 clones exhibited characteristics of autophagy. To test how cells respond to reactive oxygen species generators, the cells were treated with either hydrogen peroxide or t-butyl hydroperoxide and Bbeta2 clones induced cell death. Suppression of autophagy using either RNA interference of the essential autophagy gene or pharmacological inhibitor rescued cell death caused by oxidative stress.
  
  
  CONCLUSIONS
  Cells with ectopically expressed mitochondria-targeted regulatory subunit PPP2R2B of the holoenzyme PP2A were shown predisposed to autophagy and oxidative stress induced cell death that is related to apoptosis. The results promised a model for studying the mechanism and function of aberrant PPP2R2B expression in neuronal cells. The work provided a new target for understanding and prevention of neuropathogenesis.
authors.affiliation: Department of Life Science, National Taiwan Normal University, Taipei, Taiwan. srnt.tw@yahoo.com.tw
authors.forename: Wan-Ting
authors.initials: WT
authors.lastname: Cheng
authors.forename: Zhi-Xuan
authors.initials: ZX
authors.lastname: Guo
authors.forename: Chia-An
authors.initials: CA
authors.lastname: Lin
authors.forename: Ming-Yi
authors.initials: MY
authors.lastname: Lin
authors.forename: Li-Chu
authors.initials: LC
authors.lastname: Tung
authors.forename: Kang
authors.initials: K
authors.lastname: Fang
mesh_terms: D001343:Autophagy; D045744:Cell Line, Tumor; D006801:Humans; D008928:Mitochondria / Q000201:enzymology* / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009447:Neuroblastoma / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology*; D018384:Oxidative Stress; D054648:Protein Phosphatase 2 / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport
chemical_list: D009419:Nerve Tissue Proteins; C505936:PPP2R2B protein, human; D054648:Protein Phosphatase 2