Attenuation of microtubule-associated protein 1B expression by antisense oligodeoxynucleotides inhibits initiation of neurite outgrowth.
Microtubule-associated protein 1B, formerly also known as microtubule-associated protein 5, is the first structural microtubule accessory protein to appear in outgrowing axons. In PC12 pheochromocytoma cells microtubule-associated protein 1B levels increase several-fold after the addition of nerve growth factor and this increase is correlated with the initiation of process formation. To determine whether microtubule-associated protein 1B is essential for neurite outgrowth, we used antisense oligodeoxynucleotides to inhibit its expression in nerve growth factor-treated PC12 cells in the rat. The application of several different antisense oligodeoxynucleotides to the microtubule-associated protein 1B mRNA sequence inhibited both microtubule-associated protein 1B expression and neurite extension. Specificity was shown by the lack of effect of control sense oligonucleotides and by the lack of effect of the microtubule-associated protein 1B antisense oligodeoxynucleotides on the expression of either tubulin or microtubule-associated protein 3, another microtubule-associated protein whose synthesis is stimulated by nerve growth factor treatment of PC12 cells. After removal of the antisense oligodeoxynucleotides, microtubule-associated protein 1B expression recovered to normal levels and the cells grew normal neurites with the timing and morphological characteristics of normal nerve growth factor-induced outgrowth, indicating that the blockade was not because of non-specific toxic effects. These results indicate that microtubule-associated protein 1B is an essential component of the molecular mechanism underlying the formation of neuronal processes.
Brugg
B
B
Friedrich Miescher Institute, Basel, Switzerland.
Reddy
D
D
Matus
A
A
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D005455:Fluorescent Antibody Technique; D008869:Microtubule-Associated Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000494:pharmacology; D016501:Neurites / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D016716:PC12 Cells; D014404:Tubulin / Q000032:analysis
D008869:Microtubule-Associated Proteins; D009414:Nerve Growth Factors; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense; D014404:Tubulin