# Investigating the regulation and mechanism of tension-sensors Stu2 & Ndc80c

> **NIH NIH F31** · UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH · 2024 · $43,133

## Abstract

Project Summary
Proper chromosome segregation is vital for maintenance of eukaryotic genomes, yet the molecular mechanisms
underlying this fundamental process remain unclear. This process must occur with absolute fidelity as
detrimental aneuploidies result when it goes awry. Aneuploidy is a unifying hallmark of many different cancer
types, where it appears to be a therapeutic vulnerability. Understanding the molecular mechanisms of
chromosome segregation would give insight into how aneuploidy occurs and how it might be prevented. Our
research goal is to understand the regulation and mechanisms of chromosome segregation by probing the
function of protein factors responsible for segregating chromosomes. For proper chromosome segregation to
occur, duplicated chromosomes must become attached to microtubules originating from opposite cell poles.
When a chromosome becomes attached to microtubules from opposing poles in a correct manner, a high force
is generated. By contrast, a chromosome attached incorrectly to microtubules from the same cell pole
experiences low force. Proteins in the kinetochore complex, which forms the attachment between chromosomes
and microtubules, sense and respond to these forces. Kinetochores stabilize “correct” high-force attachments
and destabilize “incorrect” low-force attachments through unknown mechanisms, and this activity is vital for
proper chromosome segregation. Past work had shown that two conserved eukaryotic factors, Stu2 and its
kinetochore receptor the Ndc80 complex (Ndc80c), are required for tension-sensing activity, and we set out to
understand the tension-sensing mechanisms of these factors. Using structural and biochemical means, we
characterized the physical interaction between Stu2 and Ndc80c and showed that these proteins must interact
for proper chromosomes segregation in yeast. These findings are the subject of a recent publication. In this
proposal, we will determine how Stu2 and Ndc80c are regulated to control tension-sensing and we will investigate
the tension-sensing mechanism by these factors. We will analyze the effects of phosphorylation on Stu2-Ndc80c
binding and activity in yeast. Preliminary data showed Stu2 is phosphorylated near the Ndc80c binding site, and
that this phosphorylation may affect Ndc80c binding and tension-sensing. Further topology analysis of the Stu2-
Ndc80c assembly pointed to an additional interaction interface between these factors that is required for cell
viability and possibly tension-sensing. We will also investigate the tension-sensing mechanism of Stu2-Ndc80c
by reconstituting the kinetochore microtubule interface and probing it with biophysical methods. These combined
approaches will reveal important mechanistic details that are difficult, if not impossible, to obtain by other
experimental means. Our past work and preliminary data prime us to be successful in these investigations. Both
Stu2 and Ndc80c are mutated in human cancers, with several mutations found at the...

## Key facts

- **NIH application ID:** 10810659
- **Project number:** 5F31CA271740-02
- **Recipient organization:** UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH
- **Principal Investigator:** MICHAEL STEWART
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $43,133
- **Award type:** 5
- **Project period:** 2023-04-01 → 2026-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10810659

## Citation

> US National Institutes of Health, RePORTER application 10810659, Investigating the regulation and mechanism of tension-sensors Stu2 & Ndc80c (5F31CA271740-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10810659. Licensed CC0.

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