MOXI Is a Mitochondrial Micropeptide That Enhances Fatty Acid β-Oxidation

Publication date: 26 June 2018
Source:Cell Reports, Volume 23, Issue 13
Author(s): Catherine A. Makarewich, Kedryn K. Baskin, Amir Z. Munir, Svetlana Bezprozvannaya, Gaurav Sharma, Chalermchai Khemtong, Akansha M. Shah, John R. McAnally, Craig R. Malloy, Luke I. Szweda, Rhonda Bassel-Duby, Eric N. Olson
Micropeptide regulator of β-oxidation (MOXI) is a conserved muscle-enriched protein encoded by an RNA transcript misannotated as non-coding. MOXI localizes to the inner mitochondrial membrane where it associates with the mitochondrial trifunctional protein, an enzyme complex that plays a critical role in fatty acid β-oxidation. Isolated heart and skeletal muscle mitochondria from MOXI knockout mice exhibit a diminished ability to metabolize fatty acids, while transgenic MOXI overexpression leads to enhanced β-oxidation. Additionally, hearts from MOXI knockout mice preferentially oxidize carbohydrates over fatty acids in an isolated perfused heart system compared to wild-type (WT) animals. MOXI knockout mice also exhibit a profound reduction in exercise capacity, highlighting the role of MOXI in metabolic control. The functional characterization of MOXI provides insight into the regulation of mitochondrial metabolism and energy homeostasis and underscores the regulatory potential of additional micropeptides that have yet to be identified.

Graphical abstract

Teaser

Micropeptide regulator of β-oxidation (MOXI) is encoded by a muscle-enriched RNA transcript misannotated as non-coding. MOXI localizes to the inner mitochondrial membrane where it interacts with the trifunctional protein to modulate fatty acid β-oxidation and exercise capacity.


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