Proper mitochondrial function requires the coordinated expression of 37 genes encoded in the circular genome inside the mitochondrion, and over 1000 genes encoded on nuclear chromosomes. This intracellular, intergenomic communication presents a complicated network of interacting genes that are critical for the energy production that sustains life. Because each of these genes is variable in natural populations, each gene-by-gene interaction can be altered by the variation among individuals. Moreover, the mitochondrion is a hub of many signaling pathways that sense nutrients, oxygen, redox state of the cell, and temperature making it sensitive to environmental conditions. As a result, these interactions present a complex system that lies between genotype and phenotype.
The first Aim i s to dissect this mitochondrial-nuclear (mitonuclear) interaction by generating and phenotyping all pairs of genotypes from 40 well-characterized inbred strains of Drosophila (the Drosophila Genetics Reference Panel), and 6 sequenced mtDNAs from D. melanogaster and D. simulans. This will add an important mtDNA component to the DGRP resource.
This Aim will quantify metabolite profiles and resistance to hypoxic stress in alternative dietary and oxygen environments, respectively. This will test the hypothesis that environmental stress alters the epistatic component to mitonuclear interactions and further test the hypothesis that mtDNA disease states are more common in males, which do not transmit mtDNA.
The second Aim will identify specific nuclear transcripts whose expression are altered by mtDNA background and these same environmental stressors (diet composition or oxygen tension). This will test the hypothesis that genes in the pathways of central nutrient metabolism and hypoxia signaling are uniquely sensitive to mtDNA genotype. In both Aims, the genealogy of the mtDNAs used will be used in a neutrality test of mtDNA-phenotype association that allows partitioning of traits to distinct classes of mutations in the mtDNA haplotypes. Because most QTL and genome wide association studies (GWAS) do not test for mtDNA or joint mitonuclear interaction effects on phenotype, the proposed experimental design will addresses this shortcoming directly, and may identify components of 'missing heritability'not identified in GWAS. The research will also contribute to knowledge of specific pathways relevant to mitochondrial function that may lead to pharmaceutical treatments. By manipulating diet or oxygen levels in the environment, we may identify novel roles for mitonuclear interactions affecting obesity and sensitivity to hypoxic stress.

Public Health Relevance

Mitochondrial dysfunction is a leading cause of metabolic disease, affecting 1 in ~5000 individuals. Proper mitochondrial function requires coordinated expression of 37 genes in the mitochondrial genome (mtDNA) and more than 1000 genes in the nuclear genome, providing a large target for mutation. This project will dissect the joint contribution of mtDNA- and nuclear-encoded genes to metabolite levels and resistance to low oxygen. The first Aim will indentify genetic interactions between the two genomes that are sensitive to different levels of dietary carbohydrates and proteins, and to hypoxic stress, and the second Aim will identify genes whose expression are altered by mtDNA and dietary or oxygen stress. These experiments will provide information about the genetic basis of mitochondrial function for pathways related to obesity and the toxic effects of low oxygen, and could contribute to the development of mitochondrial replacement therapy or pharmaceuticals that compensate for reduced mitochondrial function.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM067862-10
Application #
8518361
Study Section
Special Emphasis Panel (ZRG1-GGG-H (02))
Program Officer
Krasnewich, Donna M
Project Start
2004-08-01
Project End
2016-07-31
Budget Start
2013-08-01
Budget End
2014-07-31
Support Year
10
Fiscal Year
2013
Total Cost
$326,677
Indirect Cost
$111,619
Name
Brown University
Department
Biology
Type
Schools of Medicine
DUNS #
001785542
City
Providence
State
RI
Country
United States
Zip Code
02912
Buchanan, Justin L; Meiklejohn, Colin D; Montooth, Kristi L (2018) Mitochondrial Dysfunction and Infection Generate Immunity-Fecundity Tradeoffs in Drosophila. Integr Comp Biol 58:591-603
Sujkowski, Alyson; Spierer, Adam N; Rajagopalan, Thiviya et al. (2018) Mito-nuclear interactions modify Drosophila exercise performance. Mitochondrion :
Rand, David M; Mossman, Jim A; Zhu, Lei et al. (2018) Mitonuclear epistasis, genotype-by-environment interactions, and personalized genomics of complex traits in Drosophila. IUBMB Life 70:1275-1288
Rand, David M (2017) Fishing for adaptive epistasis using mitonuclear interactions. PLoS Genet 13:e1006662
Mossman, Jim A; Tross, Jennifer G; Jourjine, Nick A et al. (2017) Mitonuclear Interactions Mediate Transcriptional Responses to Hypoxia in Drosophila. Mol Biol Evol 34:447-466
Mossman, Jim A; Tross, Jennifer G; Li, Nan et al. (2016) Mitochondrial-Nuclear Interactions Mediate Sex-Specific Transcriptional Profiles in Drosophila. Genetics 204:613-630
Mossman, Jim A; Biancani, Leann M; Zhu, Chen-Tseh et al. (2016) Mitonuclear Epistasis for Development Time and Its Modification by Diet in Drosophila. Genetics 203:463-84
Holmbeck, Marissa A; Rand, David M (2015) Dietary Fatty Acids and Temperature Modulate Mitochondrial Function and Longevity in Drosophila. J Gerontol A Biol Sci Med Sci 70:1343-54
Holmbeck, Marissa A; Donner, Julia R; Villa-Cuesta, Eugenia et al. (2015) A Drosophila model for mito-nuclear diseases generated by an incompatible interaction between tRNA and tRNA synthetase. Dis Model Mech 8:843-54
Villa-Cuesta, Eugenia; Rand, David M (2015) Preparation of Mitochondrial Enriched Fractions for Metabolic Analysis in Drosophila. J Vis Exp :

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