Effects of Nickel on Microtubule Assembly and the Possible Mechanisms of Nickel-Induced Perturbation in Microtubule Organization

摘要

To understand the mechanism of the nickel (7440020) induced change inmicrotubules (MTs), the effect of nickel at 0.01 to 3.0 millimolar (mM) concentrations was investigated on the kinetic parameters of in-vitro MT polymerization. Nickel-chloride (7718549) induced MT bundling in 3T3 cells. This change was both time and concentration related, and was reversible on removal of nickel from the incubation medium. Nickel had a stimulatory effect on the polymerization process of MTs in-vitro. The combination of a shortened lag time, an increase in the initial rate and the final extent of MT assembly indicates that nickel may exert its effect at the initial nucleation phase. A decrease in the critical concentration of MT protein necessary for initiation of MT assembly and an increase in the number of effective initiation centers in the presence of nickel as examined by electron microscopy confirmed the finding that nickel exerts its effect at the initial nucleation phase. MTs polymerized in-vitro in the presence of 2.0mM nickel were shorter and more numerous than those without nickel. No MT bundles were noted in the in-vitro polymerization product in the presence of 2.0mM nickel.