Effects of the alternative oxidase expression in redox metabolism

• Grant number: 25/01481-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: May 01, 2025
• End date: October 31, 2026
• Field of knowledge: Biological Sciences - Biochemistry - Metabolism and Bioenergetics
• Principal Investigator: Marcos Túlio de Oliveira
• Grantee: Geovana Siqueira Garcia
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated research grant: 21/06711-2 - Modulation of tissue growth and biomass accumulation by the mitochondrial alternative oxidase, AP.JP2

Abstract

In this project, we will investigate how alternative oxidase (AOX) influences mitochondrial metabolism, particularly under alterations in lactate dehydrogenase (LDH) levels, exploring its effects on cellular respiration, redox metabolism, and growth in Drosophila. To achieve this, we will perform high-resolution respirometry assays to assess oxygen consumption, ATP production, and ROS levels in larval tissues, including the fat body, nervous tissue, muscle, intestine, and hemolymph.We will analyze the interaction between AOX and metabolic dehydrogenases, including the malate-aspartate shuttle (MAS) and glycerol-3-phosphate shuttle (G3PS), both of which play a fundamental role in NAD+ regeneration. Furthermore, we will investigate whether AOX modulates complex I (CI) activity and the formation of mitochondrial supercomplexes (SC), potentially compensating for ATP production inefficiencies.To further explore these mechanisms, we will assess the NADH/NAD+ ratio and utilize genetically encoded spectral biosensors expressed in Drosophila to monitor lactate metabolism. Additionally, we will examine the relationship between AOX, lactate metabolism, and one-carbon metabolism (1CM), considering the pupal lethality observed in high-AOX flies under restrictive diets. Since previous studies suggest that Myc overexpression may modulate lactate metabolism and 1CM, influencing cell growth, we may also explore the effects of AOX in Myc-overexpressing strains.The mechanisms we are investigating are central to understanding the metabolism of proliferative cells, including tumor cells, which frequently reprogram their energy substrate utilization to sustain accelerated growth. By elucidating the connection between AOX, LDH, and metabolic shuttles, we aim to provide new insights into how metabolic flexibility supports cell proliferation and survival, with potential implications for understanding cancer metabolism and other conditions linked to mitochondrial dysfunction.