title: Synthetic polymeric substrates as potent pro-oxidant versus anti-oxidant regulators of cytoskeletal remodeling and cell apoptosis.
abstract: The role of reactive oxygen species (ROS)-mediated cell signal transduction pathways emanating from engineered cell substrates remains unclear. To elucidate the role, polymers derived from the amino acid L-tyrosine were used as synthetic matrix substrates. Variations in their chemical properties were created by co-polymerizing hydrophobic L-tyrosine derivatives with uncharged hydrophilic poly(ethylene glycol) (PEG, Mw = 1,000 Da), and negatively charged desaminotyrosyl-tyrosine (DT). These substrates were characterized for their intrinsic ability to generate ROS, as well as their ability to elicit Saos-2 cell responses in terms of intracellular ROS production, actin remodeling, and apoptosis. PEG-containing substrates induced both exogenous and intracellular ROS production, whereas the charged substrates reduced production of both types, indicating a coupling of exogenous ROS generation and intracellular ROS production. Furthermore, PEG-mediated ROS induction caused nuclear translocation of glyceraldehyde-3-phosphate dehydrogenase and an increase in caspase-3 activity, confirming a link with apoptosis. PEG-rich pro-oxidant substrates caused cytoskeletal actin remodeling through beta-actin cleavage by caspase-3 into fractins. The fractins co-localized to the mitochondria and reduced the mitochondrial membrane potential. The remnant cytosolic beta-actin was polymerized and condensed, events consistent with apoptotic cell shrinkage. The cytoskeletal remodeling was integral to the further augmentation of intracellular ROS production. Conversely, the anti-oxidant DT-containing charged substrates suppressed the entire cascade of apoptotic progression. We demonstrate that ROS activity serves an important role in "outside-in" signaling for cells grown on substrates: the ROS activity couples exogenous stress, driven by substrate composition, to changes in intracellular signaling. This signaling causes cell apoptosis, which is mediated by actin remodeling.
authors.affiliation: Department of Chemistry and Chemical Biology, Piscataway, New Jersey.
authors.forename: Hak-Joon
authors.initials: HJ
authors.lastname: Sung
authors.forename: Prafulla
authors.initials: P
authors.lastname: Chandra
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Treiser
authors.forename: Er
authors.initials: E
authors.lastname: Liu
authors.forename: Carmine P
authors.initials: CP
authors.lastname: Iovine
authors.forename: Prabhas V
authors.initials: PV
authors.lastname: Moghe
authors.forename: Joachim
authors.initials: J
authors.lastname: Kohn
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D048430:Cell Shape / Q000187:drug effects; D003599:Cytoskeleton / Q000187:drug effects* / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010545:Peroxides / Q000378:metabolism; D011108:Polymers / Q000737:chemistry / Q000494:pharmacology*; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017382:Reactive Oxygen Species / Q000494:pharmacology*
chemical_list: D000199:Actins; D000975:Antioxidants; D010545:Peroxides; D011108:Polymers; D017382:Reactive Oxygen Species; D049452:Green Fluorescent Proteins