Effect of DNA damage on microtubule dynamics

Abstract

The site of nucleation strongly determines microtubule organisation and dynamics. The centrosome is a primary site for microtubule nucleation and organisation in most animal cells. In recent years, the Golgi apparatus has emerged as a site of microtubule nucleation and stabilisation. The microtubules originating from Golgi are essential for maintaining Golgi integrity post-Golgi trafficking, establishing cell polarity and enabling cell motility. Although the mechanism of nucleation and functional relevance of the Golgi-nucleated microtubule is well established, its regulation needs to be better studied. In this study, we report that DNA damage leads to aberrant Golgi structure and function accompanied by reorganisation of the microtubule network. Characterisation of microtubule dynamics post DNA damage showed the presence of a stable pool of microtubules resistant to depolymerization by nocodazole and enriched in acetylated tubulin. Investigation of the functional association between Golgi dispersal and microtubule stability revealed that the Golgi elements were distributed along the acetylated microtubules. Microtubule regrowth assays showed an increase in Golgi-derived microtubule post DNA damage. Interestingly, reversal of Golgi dispersal reduces microtubule stabilisation. Altered intracellular trafficking resulting in mislocalisation of cell-cell junction proteins was observed post DNA damage. We propose that the increase in stable microtubules deregulates intracellular trafficking, resulting in cell polarity changes. This study would thus be the first to demonstrate the link between Golgi dispersal and microtubule reorganisation orchestrating changes in cell polarity.