Study of the Nucleation Stage of Microtubule Assembly

Nucleation is a crucial stage of microtubule assembly and tubulin oligomers are formed in the nucleation stage which serve as the template of microtubule formation. The project aims to study the role of nucleation stage in microtubule assembly using γ-tubulin and some nucleation inducers.

γ-tubulin exists as a complex in the cell. We have purified the γ-tubulin complex from mammalian brains. We are studying the role of mammalian brain γ-tubulin in the in vitro nucleation. We are also in the process of characterization of the nucleation phase by biochemical techniques. Efforts are going on to study the movement of γ-tubulin in the cell, both normal and cancerous, by tagging it with a reporter fluorescent protein.

Microtubule mediated drug development for anticancer therapy

We are trying to develop diaminothiazoles as potent anticancer agents based on the lead obtained for DAT1, a synthetic diaminothiazole. DAT1 was established as a cytotoxic and antimitotic agent for different cancer cell lines. It inhibits microtubule assembly in vitro and distorts microtubule organization in the cell. DAT1 binds to tubulin to the same or overlapping binding site to that of the widely used antimitotic drug colchicine. Structure-function studies and mechanistic studies of DAT1 are being started. Animal studies would be started shortly.

Drug screening through microtubule assembly

Microtubules are present in all eukaryotic cells and occupy a very important position in the modern research in cell and developmental biology. Microtubules participate in a number of important functions of the cell, including cell division and transport of material within the cell. During metaphase, the proper functioning of the spindle and the polarity of the cell depend upon microtubules and its interacting proteins. In these processes, the microtubule dynamics and the equilibrium between microtubules with its major component tubulin, play very important roles. Many antimitotic drugs influence these two phenomena in different ways by their specific binding to microtubule proteins. So, microtubules and their major constituent protein tubulin, represents the most popular target for cancer chemotherapy till now.

In our lab, we have established assays for detection of induction or inhibition of microtubule assembly from their component proteins in presence of an external agent. We are able to extend these assays for drug screening for which the target is tubulin or microtubules. Compounds can be first screened on the basis of their effect on microtubules and then the active ones can be tested for their cytotoxicity or in some other diseases where abnormalities of microtubules are involved. We can also use these assays to screen cytotoxic compounds to identify if they are microtubule targeted.