In an ongoing a collaborative project with the lab of Andrea Musacchio, we aim at reconstitution of the force-generating interface between a microtubule end and a reconstituted human kinetochore.
Microtubules exert forces on kinetochores to generate tension and movement. Correctly attached microtubules must be stabilized to prevent their detachment, while other microtubules must be destabilized and let detach. Recently we have established how force-coupling properties of this interface are regulated by mitotic kinases. We identified the duration of the kinetochore-mediated stall in microtubule shortening to be a fundamental parameter, which determines whether a microtubule will detach (after a stall shorter than 1 second) or convert to growh, in other words rescue (after a stall longer than 1 second). Phosphorylation of Ndc80 complex by Aurora B kinase leads to shorter stalls and promotes detachment. Phosphorylation of Ska complex by Cdk1 kinase enables it to interact with Ndc80, providing an additional microtubule-binding site and leading to longer stalls and rescues .
Previously, we employed precisely oligomerized full-length human Ndc80 complexes as a tool to demonstrate that Ndc80 does not need additional kinetochore components to stall a depolymerizing microtubule end and rescue its shortening in a force-dependent manner . My data suggest that only in the context of oligomers joined at the kinetochore-binding side, the Ndc80 complex acquires an ability to interact with the flared protofilaments at the microtubule tip.
I also contributed to the collaborative projects directed at understanding how the microtubule-generated forces remodel cellular membranes and how the microtubule depolymerase MCAK is regulated
I have lead a small research group studying the properties of human Centromere protein F (CENP-F) as a coupler of microtubule dynamics to motility of cargo. Using in vitro reconstitution we have demonstrated the role of N- and C-terminal microtubule-binding sites of CENP-F in coupling the motility of cellular cargos to both growing and shortening microtubule tips. Our results highlight the potential role of CENP-F in initial capture of chromosomes in prometaphase , and in redistribution of mitochondrial network after mitosis .
I had to leave this position and continue my postdoc because in 2015 the Dmitry Zimin Dynasty Foundation, my main funder, was forced by Russian government to cease its operation. Apart from loss of funding, this was a signal for me that groups collaborating with western labs are no longer welcome in Russia.
I was enrolled in graduate school in Moscow, Russia in the lab of Fazly Ataullakhanov. The actual research was done in the University of Colorado at Boulder, CO, USA as a collaboration project with the lab of Richard McIntosh. In the lab of Prof. Richard McIntosh I have shown for the first time that Ndc80 complex is able to transport a cargo with the end of depolymerizing microtubule in vitro . I have also contributed to studies that showed that ring formation is not necessary for the coupling of microtubule ends to the budding yeast Dam1 complex [11-12].
My following project was dedicated to the effect of the coupler's geometry on the amount of force measured at the depolymerizing microtubule end. I have shown that the presence of long tethers between the bead cargo and the microtubule-tracking Dam1 ring dramatically increases the force measured using the optical trap .
I used primary hepatocytes isolated from mice and rats to establish the functions of two isoforms of methionine adenosyl transferase, MATI and MATIII. I found that MATI, an isoform with slower kinetics, acts at low methionine concentrations, but it switches to a faster enzyme, MATIII, when methionine concentration rises .
I developed an HPLC method for determination of vincristine concentration in the blood samples of oncological patients.