Aluminum treatment of intact neuroblastoma cells alters neurofilament subunit phosphorylation, solubility, and proteolysis.
Addition of 400 microM AlCl3 to the culture medium for 72 h has been previously shown to induce perikaryal whorls of intermediate-sized filaments in intact mouse NB2a/d1 neuroblastoma cells. Immunoblot analyses demonstrated that in vivo treatment of cells with aluminum induced the de novo appearance of extensively phosphorylated NF-H isoforms in cytoskeletons of undifferentiated cells and increased levels of these isoforms in differentiated cells. Neurofilament subunits isolated from intact cells treated with aluminum were resistant to dephosphorylation in vitro by alkaline phosphatase and to in vitro degradation by endogenous calcium-dependent protease(s). These alterations were accompanied by a greater tendency of neurofilaments to form insoluble aggregates after isolation. These findings demonstrate direct effects of aluminum on neurofilament subunits within intact neuronal cells similar to those previously demonstrated following in vitro exposure of isolated neurofilaments to aluminum.
Shea
T B
TB
Department of Biological Sciences, University of Massachusetts at Lowell 01854, USA.
Beermann
M L
ML
Nixon
R A
RA
D000818:Animals; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D006868:Hydrolysis; D051379:Mice; D008970:Molecular Weight; D009447:Neuroblastoma; D016900:Neurofilament Proteins / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D010766:Phosphorylation; D012995:Solubility; D014407:Tumor Cells, Cultured
D016900:Neurofilament Proteins