title: Kinase activity, heat shock protein 27 phosphorylation, and lung epithelial cell glutathione.
abstract: The 27-kDa heat shock protein (Hps27) is phosphorylated in a way that appears to regulate antioxidant defenses by mitogen-activated protein kinase (MAPK)-activated protein kinase 2 (MK2), a component of the p38(MAPK) pathway. To investigate the role of Hsp27 in cellular resistance to oxidant stress, lung cells (A549) were incubated with MAPK inhibitors to investigate the pathway's role in antioxidant defense. Cells were harvested for measurement of reduced gluthathione and glutathione disulfide (GSH and GSSH); or, exposed to 2,3-dimethoxy-1,4-napthoquinone (DMNQ). Inhibition of MAPK with SB203580 decreased total cellular glutathione (mean +/- SE): Vehicle, 150 +/- 20 mu M; SB203580, 57 +/- 10* (*P < .01). Inhibition of MAPK tripled [GSSG]/[GSH]: Vehicle, 0.29 +/- 0.09; SB203580, 1.06 +/- 0.43* (*P > .05; n = 6 per group). Hsp27 protein content did not change significantly after MAPK inhibition: Vehicle 2.20 +/- 0.24 ng/mg protein; SB203580, 2.03 +/- 0.34 (P > .05). Transfection of epithelial cells with wild-type (pcDNA-HA-Hsp27) or phosphomimic (pcDNA-HA-Hsp27-S3D) vector increased Hsp27 protein, which significantly protected cells from oxidant stress. Inhibition of the MAPK system, including p38(MAPK), results in cellular oxidant stress. Hsp27, which is phosphorylated by MK2 in the MAPK pathway, protects epithelial cells from oxidant stress.
authors.affiliation: Miami VA Hospital System, Miami, Florida, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Jackson
authors.forename: Rolando
authors.initials: R
authors.lastname: Garcia-Rojas
mesh_terms: D000231:Adenocarcinoma, Papillary; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology*; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008175:Lung Neoplasms; D009285:Naphthoquinones / Q000494:pharmacology; D018384:Oxidative Stress; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D020545:Respiratory Mucosa / Q000187:drug effects / Q000201:enzymology*; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000099190:MAP-Kinase-Activated Kinase 2
chemical_list: D004791:Enzyme Inhibitors; D005978:Glutathione; D019803:Glutathione Disulfide; D007093:Imidazoles; D047908:Intracellular Signaling Peptides and Proteins; D009285:Naphthoquinones; D017346:Protein Serine-Threonine Kinases; D011725:Pyridines; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2; C063002:2,3-dimethoxy-1,4-naphthoquinone; C093642:SB 203580