# Defining Molecular Interactions that Drive Mitochondrial Fission

> **NIH NIH R01** · CASE WESTERN RESERVE UNIVERSITY · 2021 · $322,000

## Abstract

ABSTRACT
 The molecular mechanism of mitochondrial fission is not known. This process is essential and closely
regulated through a variety of modifications to the major protein factor of the mitochondrial fission complex,
Drp1. The goal of this proposal is to identify key molecular interactions within the mitochondrial fission complex
and to understand regulatory changes that influence these interactions and ultimately affect mitochondrial
fission. To begin, structures of larger, helical Drp1 oligomers on membrane templates will be studied to identify
conformational changes in the Drp1 protein that promote self-assembly at the surface of mitochondria.
Specifically, cryo-EM and mitochondrial isolation studies will be performed in parallel to reveal interactions
within the mitochondrial fission complex adjacent to the neighboring membrane. In parallel, detailed
interactions within Drp1 complexes will be identified using proteomics and mutagenesis methods. Factors that
perturb Drp1 self-assembly also disrupt organelle morphology, so Drp1 interactions with the essential partner
protein, Mff, will also be examined. Specifically, protein co-polymers will be characterized using structural
methods to uncover the mechanism by which Drp1 is targeted to the surface of mitochondria and how Mff
contributes to productive mitochondrial fission. To mimic changes associated with human disease, Drp1
sequence will be altered using site-directed mutagenesis to recapitulate natural sequence changes caused by
post-translational modifications. The full effects of these changes will be assessed using structural and
biochemical assays, and noticeable differences between healthy and diseased mitochondrial fission complexes
will be identified. These same changes will be introduced in cell culture to correlate alterations in mitochondrial
morphology to functional alterations observed in vitro. To further characterize the impact of these changes, we
plan to assess the bioenergetic capacities of stable cell lines expressing phosphomimetic mutants. Moreover,
the assembly properties of Drp1 and its partner proteins will be assayed in the context of post-translational
modifications to reveal the underlying effects of cell signaling alterations that modify the mitochondrial network.
Collectively, this project seeks to identify detailed features within the mitochondrial fission complex that
contribute to specific disease states. These differences provide novel targets for the development of future
therapeutics that prevent cell death in neurological disorders, which are associated with increased Drp1 activity
and excessive mitochondrial fission.

## Key facts

- **NIH application ID:** 10093072
- **Project number:** 5R01GM125844-04
- **Recipient organization:** CASE WESTERN RESERVE UNIVERSITY
- **Principal Investigator:** Jason Mears
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $322,000
- **Award type:** 5
- **Project period:** 2018-02-01 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10093072

## Citation

> US National Institutes of Health, RePORTER application 10093072, Defining Molecular Interactions that Drive Mitochondrial Fission (5R01GM125844-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10093072. Licensed CC0.

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