# Mitochondrial metabolite compartmentalization in health and disease

> **NIH NIH DP1** · BETH ISRAEL DEACONESS MEDICAL CENTER · 2022 · $875,000

## Abstract

Project Summary
Eukaryotic cells store and utilize metabolites in different organelles – referred to as subcellular metabolite
compartmentalization. Distinct pools of metabolic enzymes and substrates provide another layer of flexibility in
metabolite utilization, thereby allowing for robust adaptation to a variety of intrinsic cues and external stress. In
turn, defects in the processes are associated with metabolic disorders, including obesity, insulin resistance, and
diabetes. One of the critical regulators of metabolite compartmentalization is mitochondrial transporters: a large
number of carrier proteins, many of which belong to the SLC25A protein family, mediate the translocation of
metabolites across the impermeable mitochondrial inner-membrane and control their availability in the
mitochondrial matrix. However, a vast majority of the mitochondrial SLC25A carrier proteins are “orphan”
transporters, i.e., their specific substrates and biological functions remain unknown.
The lack of our knowledge is primarily due to the fact that many mitochondrial membrane proteins cannot be
reconstituted correctly in the conventional experimental system, i.e., liposomes using recombinant proteins made
in E. Coli or yeast. To circumvent this issue, we developed a robust experimental platform that enables systemic
characterization of mammalian mitochondrial transporters using brown fat, one of the most mitochondria-
enriched cells. We incorporated the CRISPRi and CRISPRa system in immortalized brown adipocytes, such that
we can obtain essentially unlimited amounts of “designer mitochondria” in mice and humans. By employing the
new system, my lab has recently identified SLC25A44 as the first mitochondrial BCAA transporter in mammals,
a long-standing mystery in the field (Yoneshiro et al. Nature 2019).
This proposal aims to generate a complete functional map of mitochondrial SLC25A metabolite transporters in
mammals. To achieve this goal, we plan to apply the state-of-art metabolomics and mitochondrial-liposomes to
the brown fat-derived designer mitochondria, and to determine the specific substrates for orphan SLC25A carrier
proteins. We will further determine the physiological and pathological roles of orphan SLC25A transporters in
vivo, with an emphasis on metabolic disorders. The work resulting from this application will establish a conceptual
framework to understand the molecular regulation of mitochondrial metabolite compartmentalization, and also
provide a new roadmap for reversing disease phenotypes that stem from defects in such processes.

## Key facts

- **NIH application ID:** 10435518
- **Project number:** 5DP1DK126160-03
- **Recipient organization:** BETH ISRAEL DEACONESS MEDICAL CENTER
- **Principal Investigator:** Shingo Kajimura
- **Activity code:** DP1 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $875,000
- **Award type:** 5
- **Project period:** 2020-08-01 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10435518

## Citation

> US National Institutes of Health, RePORTER application 10435518, Mitochondrial metabolite compartmentalization in health and disease (5DP1DK126160-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10435518. Licensed CC0.

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