title: Diazoxon disrupts the expression and distribution of βIII-tubulin and MAP 1B in differentiating N2a cells.
abstract: This study aimed at assessing the effects of diazoxon (DZO), a major metabolite of the insecticide diazinon (DZ), on key cytoskeletal proteins in differentiating N2a neuroblastoma cells. Initial experiments established that sublethal concentrations of 1, 5 and 10 μM DZO produced profound inhibition of neurite outgrowth. Densitometric scanning of probed immunoblots of N2a cell lysates demonstrated that DZO had no effect on total β-tubulin levels. However, probing with a monoclonal antibody that recognised specifically the βIII-tubulin isotype revealed that 10 μM DZO induced a significant reduction in the levels of this particular form. Levels of polyglutamylated tubulin were not altered. Exposure to 10 μM DZO also decreased the expression of microtubule-associated protein 1B (MAP 1B). However, DZO had no effect on the expression of MAP tau. DZO also failed to affect the levels neurofilament light (NFL) and neurofilament medium (NFM) chain levels. Indirect immunofluorescence demonstrated that the staining of neurites in treated cells was weaker than in the controls for βIII-tubulin. In conclusion, DZO disrupts the microtubule (MT) network affecting the expression and distribution of two specific MT proteins known to be important in neuritogenesis. DZO may contribute to the developmental neurotoxicity seen following exposure to DZ.
authors.affiliation: Laboratory of Biochemistry and Toxicology, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Magdalini
authors.initials: M
authors.lastname: Sachana
authors.forename: Erasmia
authors.initials: E
authors.lastname: Sidiropoulou
authors.forename: John
authors.initials: J
authors.lastname: Flaskos
authors.forename: Wayne
authors.initials: W
authors.lastname: Harris
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Robinson
authors.forename: Zerai
authors.initials: Z
authors.lastname: Woldehiwet
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Hargreaves
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D019084:Fluorescent Antibody Technique, Indirect; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000032:analysis*; D009447:Neuroblastoma / Q000473:pathology; D020258:Neurotoxicity Syndromes / Q000209:etiology; D009943:Organophosphorus Compounds / Q000633:toxicity*; D014404:Tubulin / Q000032:analysis*
chemical_list: D008869:Microtubule-Associated Proteins; D009943:Organophosphorus Compounds; D014404:Tubulin; C462941:beta3 tubulin, mouse; C085284:microtubule-associated protein 1B; C000912:diazoxon