# Coupling kinetochore microtubule dynamics to chromosome motion

> **NIH NIH R01** · UNIVERSITY OF PENNSYLVANIA · 2020 · $398,428

## Abstract

PROJECT SUMMARY
Accurate chromosome segregation crucially depends on the dynamic attachments between
chromosomal kinetochores and spindle microtubules. Recent years brought tremendous
progress in identifying molecular components of the kinetochores, but mechanistic studies of
how these proteins interact with microtubules and enable chromosome motions are lagging
behind. We propose to address this deficiency by using reductionist multiscale approaches and
innovative assays that reconstitute physiological aspects of kinetochore-microtubule interactions
in vitro. We have molecular tools, equipment and expertise to address in a quantitative and
rigorous manner some of the most fundamental questions about mitotic chromosome
segregation: (1) how the kinetochores convert their initial microtubule-wall binding into
microtubule-end attachment, (2) how they subsequently hang onto the microtubule ends and
move in conjunction with tubulin assembly/disassembly, (3) and how these mobile links persist
under force. In Aim 1 we will recreate these interactions using purified Ndc80 protein complex
and strategically chosen assisting proteins. We recently reconstituted microtubule end
conversion by Ndc80, assisted by a plus-end directed kinesin CENP-E. Different Ndc80 variants
will be used to uncover the underlying mechanism, and additional kinetochore components will
be added to reveal their relative impact. Our findings with purified components will be critically
compared with the activity of native kinetochore complexes isolated from extracts of mitotic
human cells (Aim 2). We have found that complexes associated with the kinetochore scaffold
protein CENP-T can move at the dissembling microtubule ends. This essential achievement
lays the groundwork for our functional assays, and subsequent identification and
characterization of key kinetochore components for microtubule end coupling in human cells. In
Aim 3 we will use advanced laser tweezers techniques to critically compare the ability of purified
proteins and complexes to move under pulling force, mimicking tension between sister
kinetochores. The results from these studies will help us to construct an integrative view of the
mechano-molecular coupling at human kinetochore, define the specific roles of key kinetochore
proteins Ndc80, Ska1 and others, and reveal functional difference between kinetochore
complexes assembled with different scaffolds. Little is known about functional behavior of
human kinetochore proteins, and our research will undoubtedly provide novel insights into the
fundamentals of kinetochore-microtubule interactions, and promote new discoveries in the cell
division field.

## Key facts

- **NIH application ID:** 9995485
- **Project number:** 5R01GM098389-09
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Ekaterina L Grishchuk
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $398,428
- **Award type:** 5
- **Project period:** 2012-09-30 → 2022-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9995485

## Citation

> US National Institutes of Health, RePORTER application 9995485, Coupling kinetochore microtubule dynamics to chromosome motion (5R01GM098389-09). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9995485. Licensed CC0.

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