# Molecular mechanisms of the mitochondrial calcium uniporter

> **NIH NIH R01** · UNIVERSITY OF COLORADO DENVER · 2022 · $311,000

## Abstract

Project Summary/Abstract
The mitochondrial calcium uniporter (the uniporter) is a multi-subunit Ca2+ ion channel that imports
cytoplasmic Ca2+ into the mitochondrial matrix. In mammalian cells, the uniporter plays a crucial role
in regulating ATP generation, buffering intracellular Ca2+, and modulating cell-death pathways. Its
dysfunction has been implicated in a wide range of pathological conditions, including a human
neuromuscular disorder characterized by proximal myopathy and learning difficulties. This project
seeks to expand the knowledge base in the molecular mechanisms underlying the uniporter's key
roles in pathophysiology. Specific aims include developing new electrophysiological tools, and using
established methods to address fundamental questions in ion transport and gating. Currently,
mechanistic studies of the uniporter have been impeded by a technical barrier: The small size of
mitochondria makes it difficult to apply patch-clamp electrophysiology to analyze the channel in
native environments. In Aim #1, we solved this problem by targeting uniporter proteins to alternative
membrane systems, including reconstituted phospholipid bilayers and cell plasma membranes. Both
systems offer much straightforward electrophysiological access for high-resolution recordings in
macroscopic and single-channel levels. We plan to fully establish these tools so that researchers
can begin to adopt classical ion-channel electrophysiology to illuminate most fundamental
mechanisms of the uniporter. While developing new techniques, we will also use a CRISPR-based
strategy already in use in my lab to attack key mechanistic questions. (1) How does a regulatory
MICU1 subunit inactivate the uniporter in resting cellular conditions (Aim #2)? (2) How do MCU and
EMRE, the membrane-embedded subunits of the uniporter, form an open Ca2+ pathway for Ca2+ to
permeate mitochondrial membranes (Aim #3)? Several results, including a mutation that
unexpectedly abolishes uniporter inactivation by MICU1, and the discovery of a unique MCU
chimera that can conduct Ca2+ without EMRE present, allow us to formulate logical and testable
hypotheses to answer these important but also difficult questions. Completion of this project can
improve the scientific knowledge necessary to design new therapies to treat disease by modulating
mitochondrial Ca2+ homeostasis. Moreover, human uniporter proteins purified here can be used for
high-throughput screening assays to identify uniporter-targeting pharmacological compounds. New
electrophysiological methods will allow detailed analysis of drug kinetics, required to improve lead
compounds for potential therapeutic use.

## Key facts

- **NIH application ID:** 10440255
- **Project number:** 5R01GM129345-06
- **Recipient organization:** UNIVERSITY OF COLORADO DENVER
- **Principal Investigator:** Ming-Feng Tsai
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $311,000
- **Award type:** 5
- **Project period:** 2018-09-01 → 2024-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10440255

## Citation

> US National Institutes of Health, RePORTER application 10440255, Molecular mechanisms of the mitochondrial calcium uniporter (5R01GM129345-06). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10440255. Licensed CC0.

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