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Updated: Jan 30, 2026
Assay for Phosphorylation and Microtubule Binding Along with Localization of Tau Protein in Colorectal Cancer Cells
Published on: October 10, 2017
The regulatory effect of Tau protein on polymerization of MCF7 microtubules in vitro
Mitra Shojania Feizabadi1, Marcos A V Hernandez1, Jane B Breslin1
1Department of Physics, Seton Hall University, 400 South Orange Ave., South Orange, NJ 07079, USA.
Abstract:
Growing evidence continues to point toward the critical role of beta tubulin isotypes in regulating some intracellular functions. Changes that were observed in the microtubules' intrinsic dynamics, the way they interact with some chemotherapeutic agents, or differences on translocation specifications of some molecular motors along microtubules, were associated to their structural uniqueness in terms of beta tubulin isotype distributions. These findings suggest that the effects of microtubule associated proteins (MAPs) may also vary on structurally different microtubules. Among different microtubule associated proteins, Tau proteins, which are known as neuronal MAPs, bind to beta tubulin, stabilize microtubules, and consequently promote their polymerizations. In this study, in a set of well controlled experiments, the direct effect of Tau proteins on the polymerization of two structurally different microtubules, porcine brain and breast cancer (MCF7), were tested and compared. Remarkably, we found that in contrast with the promoted effect of Tau proteins on brain microtubules' polymerization, MCF7 expressed a demoted polymerization while interacting with Tau proteins. This finding can potentially be a novel insight into the mechanism of drug resistance in some breast cancer cells. It has been reported that microtubules show destabilizing behavior in some MCF7 cells with overexpression of Tau protein when treated with a microtubules' stabilizing agent, Taxol. This behavior has been classified by others as drug resistance, but it may instead be potentially caused by a competition between the destabilizing effect of the Tau protein and the stabilizing effect of the drug on MCF7 microtubules. Also, we quantified the polarization coefficient of MCF7 microtubules in the presence and absence of Tau proteins by the electro-orientation method and compared the values. The two significantly different values obtained can possibly be one factor considered to explain the effect of Tau proteins on the polymerization of MCF7 microtubules.
Insights
Tau proteins promote brain microtubule polymerization but inhibit breast cancer (MCF7) cell polymerization. This differential effect on microtubules may offer new insights into cancer drug resistance mechanisms.
Area of Science:
- Cell Biology
- Biochemistry
- Cancer Research
Background:
- Beta tubulin isotypes play critical roles in intracellular functions, influencing microtubule dynamics and interactions.
- Microtubule-associated proteins (MAPs), like Tau, bind to beta tubulin and affect microtubule polymerization.
- Structural differences in beta tubulin isotypes suggest varying MAP effects on different microtubule types.
Purpose of the Study:
- To investigate the direct effect of Tau proteins on the polymerization of two distinct microtubule types: porcine brain and MCF7 breast cancer cells.
- To compare the polymerization responses of brain and MCF7 microtubules when interacting with Tau proteins.
- To explore the potential implications of these differential effects on cancer drug resistance.
Main Methods:
- Controlled experiments comparing Tau protein effects on porcine brain and MCF7 microtubule polymerization.
- Quantification of the polarization coefficient of MCF7 microtubules using electro-orientation in the presence and absence of Tau proteins.
Main Results:
- Tau proteins significantly promoted polymerization in brain microtubules.
- Conversely, Tau proteins demoted polymerization in MCF7 breast cancer cell microtubules.
- Significantly different polarization coefficients were observed for MCF7 microtubules with and without Tau proteins.
Conclusions:
- Tau proteins exhibit differential effects on microtubule polymerization based on their structural isotype.
- The demotion of MCF7 microtubule polymerization by Tau may contribute to observed drug resistance phenomena.
- Further investigation into Tau-microtubule interactions could reveal novel mechanisms underlying breast cancer drug resistance.
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