Organophosphorus compounds alter intracellular F-actin content in SH-SY5Y human neuroblastoma cells.
Cytoskeletal components, especially f-actin (filamentous actin), are responsible for neurite extension and maintenance. Alterations in neurite length and quality precede in vitro cell death induced by organophosphorus (OP) compounds and implicate f-actin proteins in this process. We, therefore, investigated changes in f-actin in SH-SY5Y human neuroblastoma cells exposed to 0.1 and 1 mM paraoxon, parathion, phenyl saligenin phosphate (PSP), tri-ortho-tolyl phosphate (TOTP), triphenyl phosphite (TPPi), and di-isopropyl phosphorofluoridate (DFP) for 0-48 h. The f-actin was measured by flow cytometry in cells labeled with Alexa 488 phalloidin. The relative amount off-actin was compared to total protein levels as determined by spectrophotometry. The cellular content of f-actin significantly decreasedfollowing exposure to PSP (0.1 mM, >30 min; 1 mM, >15 min), TOTP (0.1 mM, 16 h; 1 mM, >15 min), TPPi (1 mM, >4 h), paraoxon (1 mM, >24 h), and parathion (1 mM, 48 h). Exposure to DFP (0.1 and 1 mM) did not significantly alter f-actin content at any time point. Exposure to parathion (0.1 mM, 48 h) significantly increased the amount of cellular f-actin. Total protein was significantly decreased after exposure to PSP (0.1 and 1 mM, >8 h) and TPPi (1 mM, 48 h). Significant increases in total protein were observed following exposure to parathion (0.1 mM, >3 h). Consistent alterations in the protein content of DFP-exposed samples were not observed. These results suggest that the loss off-actin is an early event following OP compound exposure and that this loss significantly precedes a loss of protein content for some OP compounds (PSP, TPPi). Results also imply that under other exposure conditions (TOTP, paraoxon, parathion) alterations in the f-actin content are independent of protein content.
Carlson
K
K
Laboratory of Neurotoxicity Studies, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA 24061, USA.
Ehrich
M
M
D000199:Actins / Q000378:metabolism*; D001932:Brain Neoplasms / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D008856:Microscopy, Fluorescence; D009363:Neoplasm Proteins / Q000378:metabolism; D009447:Neuroblastoma / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D000199:Actins; D009363:Neoplasm Proteins; D009943:Organophosphorus Compounds