# Supplement: Defining Molecular Interactions that Drive Mitochondrial Fission

> **NIH NIH R01** · CASE WESTERN RESERVE UNIVERSITY · 2024 · $150,786

## Abstract

PROJECT SUMMARY (ABSTRACT)
 Mitochondria are double-membrane organelles that change shape, size and abundance in response to
specific stimuli. Protein interactions that control mitochondrial division are tightly regulated and directly impact
ATP production, Ca2+ homeostasis, and regulation of programmed cell death. Therefore, mitochondrial
dynamics has recently come to the forefront as a therapeutic target in several degenerative diseases, including
neurodegeneration, cancer, and cardiovascular disease. But the lack of insight into the regulation of this
process is a major limitation. The major driver of mitochondrial division is a cytosolic GTPase, dynamin-related
protein 1 (Drp1). To mediate membrane scission, Drp1 recruitment and self-assembly is coordinated through
combinatorial interactions with lipids, proteins and nucleotides at the surface of mitochondria. This proposal
seeks to identify key attributes of the mitochondrial division machinery and how dysregulation of Drp1 leads to
organelle damage and cellular degeneration. This will be accomplished using a multifaceted approach that
combines molecular studies with functional cell experiments to provide a comprehensive evaluation of Drp1
interactions that govern membrane remodeling. Under Specific Aim 1 of the renewal, cryo-EM studies will
examine auto-inhibitory interactions that limit Drp1 oligomerization in a cytosolic state. Distinct conformations
will be studied to identify and characterize intermediate structures during recruitment and assembly of Drp1
into a functional fission complex. We propose that regulated rearrangements “open” the molecule for functional
assembly at defined sites of mitochondrial division. For Specific Aim 2, reconstitution experiments provide a
means to evaluate macromolecular interactions that drive mitochondrial membrane remodeling. Specific
mitochondrial cues, including lipids and partner proteins, will be studied to evaluate the contribution of each
component to membrane remodeling. Constriction of protein-lipid tubules will be encouraged to evaluate the
magnitude of constriction using advanced structural methods. Liquid-EM will visualize dynamic narrowing of
Drp1-lipid tubules in real time, and cryo-ET will be used to resolve 3D structures of assorted Drp1 constriction
events in parallel. In Specific Aim 3, defects in mitochondrial fission will be examined at the cellular level to
establish how deleterious changes in Drp1 can directly influence mitochondrial bioenergetics. The integrity of
ETC complexes will be studied to reveal how altered organelle morphology informs metabolic stress.
Concurrently, the impact of this stress on ROS signaling and mitophagy will be monitored. In summary, the
structural and functional insight gained from this proposal will catalyze directed therapeutic strategies that
counteract mitochondrial damage in various disease states.

## Key facts

- **NIH application ID:** 11099063
- **Project number:** 3R01GM125844-06S1
- **Recipient organization:** CASE WESTERN RESERVE UNIVERSITY
- **Principal Investigator:** Jason Mears
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $150,786
- **Award type:** 3
- **Project period:** 2018-02-01 → 2027-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11099063

## Citation

> US National Institutes of Health, RePORTER application 11099063, Supplement: Defining Molecular Interactions that Drive Mitochondrial Fission (3R01GM125844-06S1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/11099063. Licensed CC0.

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