Impairment of Muscle Function Causes Pupal Lethality in Flies Expressing the Mitochondrial Alternative Oxidase

The mitochondrial alternative oxidase (AOX) from the tunicate <i>Ciona intestinalis</i> has been explored as a potential therapeutic enzyme for human mitochondrial diseases, yet its systemic effects remain poorly understood. Here, we investigate the metabolic and physiological consequenc...

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Main Authors: Carlos A. Couto-Lima, Sina Saari, Geovana S. Garcia, Gabriel H. Rocha, Johanna ten Hoeve, Eric Dufour, Marcos T. Oliveira
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Biomolecules
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Online Access:https://www.mdpi.com/2218-273X/15/4/570
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author Carlos A. Couto-Lima
Sina Saari
Geovana S. Garcia
Gabriel H. Rocha
Johanna ten Hoeve
Eric Dufour
Marcos T. Oliveira
author_facet Carlos A. Couto-Lima
Sina Saari
Geovana S. Garcia
Gabriel H. Rocha
Johanna ten Hoeve
Eric Dufour
Marcos T. Oliveira
author_sort Carlos A. Couto-Lima
collection DOAJ
description The mitochondrial alternative oxidase (AOX) from the tunicate <i>Ciona intestinalis</i> has been explored as a potential therapeutic enzyme for human mitochondrial diseases, yet its systemic effects remain poorly understood. Here, we investigate the metabolic and physiological consequences of AOX expression during the development of <i>Drosophila</i> cultured under dietary stress. We show that the combination of strong, ubiquitous AOX expression and a low-nutrient condition leads to pupal lethality and severe defects in larval musculature, characterized by actin aggregation and muscle shortening. These structural abnormalities correlate with a decrease in larval biomass and motility. Interestingly, the muscle defects and the motility impairments vary in severity among individuals, predicting survival rates at the pupal stage. AOX expression in specific tissues (muscle, nervous system or fat body) does not individually recapitulate the lethal phenotype observed with ubiquitous expressions of the enzyme, indicating a complex metabolic imbalance. Metabolomic analysis revealed that the low-nutrient diet and AOX expression have opposite effects on most metabolites analyzed, especially in the levels of amino acids. Notably, supplementation of the low-nutrient diet with the essential amino acids methionine and/or tryptophan partially rescues pupal viability, body size, muscle morphology, and locomotion, whereas supplementation with proline and/or glutamate does not, highlighting a specific perturbation in amino acid metabolism rather than general bioenergetic depletion. These findings demonstrate that AOX expression disrupts metabolic homeostasis, with developmental and physiological consequences that must be considered when evaluating AOX for therapeutic applications.
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spelling doaj-art-05de6175d4ad44b28ae3f52c2cfc9c702025-08-20T02:28:40ZengMDPI AGBiomolecules2218-273X2025-04-0115457010.3390/biom15040570Impairment of Muscle Function Causes Pupal Lethality in Flies Expressing the Mitochondrial Alternative OxidaseCarlos A. Couto-Lima0Sina Saari1Geovana S. Garcia2Gabriel H. Rocha3Johanna ten Hoeve4Eric Dufour5Marcos T. Oliveira6Departamento de Biotecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, Universidade Estadual Paulista “Júlio de Mesquita Filho”, Jaboticabal 14884-900, SP, BrazilFaculty of Medicine and Health Technology, Tampere University, 33520 Tampere, FinlandDepartamento de Biotecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, Universidade Estadual Paulista “Júlio de Mesquita Filho”, Jaboticabal 14884-900, SP, BrazilDepartamento de Biotecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, Universidade Estadual Paulista “Júlio de Mesquita Filho”, Jaboticabal 14884-900, SP, BrazilUCLA Metabolomics Center, Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, CA 90095, USAFaculty of Medicine and Health Technology, Tampere University, 33520 Tampere, FinlandDepartamento de Biotecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, Universidade Estadual Paulista “Júlio de Mesquita Filho”, Jaboticabal 14884-900, SP, BrazilThe mitochondrial alternative oxidase (AOX) from the tunicate <i>Ciona intestinalis</i> has been explored as a potential therapeutic enzyme for human mitochondrial diseases, yet its systemic effects remain poorly understood. Here, we investigate the metabolic and physiological consequences of AOX expression during the development of <i>Drosophila</i> cultured under dietary stress. We show that the combination of strong, ubiquitous AOX expression and a low-nutrient condition leads to pupal lethality and severe defects in larval musculature, characterized by actin aggregation and muscle shortening. These structural abnormalities correlate with a decrease in larval biomass and motility. Interestingly, the muscle defects and the motility impairments vary in severity among individuals, predicting survival rates at the pupal stage. AOX expression in specific tissues (muscle, nervous system or fat body) does not individually recapitulate the lethal phenotype observed with ubiquitous expressions of the enzyme, indicating a complex metabolic imbalance. Metabolomic analysis revealed that the low-nutrient diet and AOX expression have opposite effects on most metabolites analyzed, especially in the levels of amino acids. Notably, supplementation of the low-nutrient diet with the essential amino acids methionine and/or tryptophan partially rescues pupal viability, body size, muscle morphology, and locomotion, whereas supplementation with proline and/or glutamate does not, highlighting a specific perturbation in amino acid metabolism rather than general bioenergetic depletion. These findings demonstrate that AOX expression disrupts metabolic homeostasis, with developmental and physiological consequences that must be considered when evaluating AOX for therapeutic applications.https://www.mdpi.com/2218-273X/15/4/570mitochondriaamino acid metabolismnutrient deprivationoxidative phosphorylationmusculature
spellingShingle Carlos A. Couto-Lima
Sina Saari
Geovana S. Garcia
Gabriel H. Rocha
Johanna ten Hoeve
Eric Dufour
Marcos T. Oliveira
Impairment of Muscle Function Causes Pupal Lethality in Flies Expressing the Mitochondrial Alternative Oxidase
Biomolecules
mitochondria
amino acid metabolism
nutrient deprivation
oxidative phosphorylation
musculature
title Impairment of Muscle Function Causes Pupal Lethality in Flies Expressing the Mitochondrial Alternative Oxidase
title_full Impairment of Muscle Function Causes Pupal Lethality in Flies Expressing the Mitochondrial Alternative Oxidase
title_fullStr Impairment of Muscle Function Causes Pupal Lethality in Flies Expressing the Mitochondrial Alternative Oxidase
title_full_unstemmed Impairment of Muscle Function Causes Pupal Lethality in Flies Expressing the Mitochondrial Alternative Oxidase
title_short Impairment of Muscle Function Causes Pupal Lethality in Flies Expressing the Mitochondrial Alternative Oxidase
title_sort impairment of muscle function causes pupal lethality in flies expressing the mitochondrial alternative oxidase
topic mitochondria
amino acid metabolism
nutrient deprivation
oxidative phosphorylation
musculature
url https://www.mdpi.com/2218-273X/15/4/570
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