The Effect of Microtubule-Associated Protein Tau on Polymerization of Cancer Microtubules

One of the cellular microtubule-associated proteins (MAPs), Tau protein, can regulate the polymerization of microtubules. The effect of Tau protein, which is known as a neuronal MAP, on neuronal microtubules have been well studied. This protein has the stabilizing effect on polymerization of neuronal microtubules and therefore, enhances their polymerization. Tau protein has also been observed in some cancer cells such as human breast cancer cells. In this study the in vitro effect of Tau protein on polymerization of breast cancer microtubules will be discussed and compared with the one obtained from brain microtubules. Our results indicate that in contrast with the stabilizing effect of tau protein on the polymerization of neuronal microtubules, breast cancer microtubules in vitro do not display promoted polymerization behavior. In contrast with the structure of neuronal microtubules, human breast cancer microtubules consist of different beta tubulin isotype distributions. In addition, Tau proteins interact with beta tubulins. Collectively, the observed distinct polymerization behavior observed may possibly be associated to the way that Tau protein interacts with different beta tubulin isotypes.