RNA-Sequencing ofDrosophila melanogasterHead Tissue on High-Sugar and High-Fat Diets

Abstract

Obesity has been shown to increase risk for cardiovascular disease and type-2 diabetes. In addition, it has been implicated in aggravation of neurological conditions such as Alzheimer’s. In the model organism Drosophila melanogaster, a physiological state mimicking diet-induced obesity can be induced by subjecting fruit flies to a solid medium disproportionately higher in sugar than protein, or that has been supplemented with a rich source of saturated fat. These flies can exhibit increased circulating glucose levels, increased triglyceride content, insulin-like peptide resistance, and behavior indicative of neurological decline. We subjected flies to variants of the high-sugar diet, high-fat diet, or normal (control) diet, followed by a total RNA extraction from fly heads of each diet group for the purpose of Poly-A selected RNA-Sequencing. Our objective was to identify the effects of obesogenic diets on transcriptome patterns, how they differed between obesogenic diets, and identify genes that may relate to pathogenesis accompanying an obesity-like state. Gene ontology analysis indicated an overrepresentation of affected genes associated with immunity, metabolism, and hemocyanin in the high-fat diet group, and CHK, cell cycle activity, and DNA binding and transcription in the high-sugar diet group. Our results also indicate differences in the effects of the high-fat diet and high-sugar diet on expression profiles in head tissue of flies, despite the reportedly similar phenotypic impacts of the diets. The impacted genes, and how they may relate to pathogenesis in the Drosophila obesity-like state, warrant further experimental investigation.

Life-History Evolution and the Genetics of Fitness Components inDrosophila melanogaster

“…In terms of molecular mechanisms, insights into the physiological underpinnings of DR and dietary plasticity have come from analyses of gene expression changes (Pletcher et al 2002;Carsten et al 2005;Gershman et al 2007;Ding et al 2014;Whitaker et al 2014;Stanley et al 2017;Zandveld et al 2017;Hemphill et al 2018), and many studies have sought to identify genes that underlie DR-induced longevity using mutants and transgenes, with growing (but still ambiguous) evidence for an involvement of genes in the insulin/insulin-like growth factor signaling (IIS)/target of rapamycin (TOR) pathways [reviewed in Tatar et al (2014); also cf. discussion in Flatt (2009), Hoedjes et al (2017), and Flatt and Partridge 2018].…”

Obesity and Aging in the Drosophila Model

“…The detrimental effect of HSD on the heart is mediated solely by the hexosamine flux, and the cardiac-specific reduction of this pathway fully protects the heart from the HSD-induced pathologies [ 19 ]. In addition, the recent RNA-seq analyses of the HSD-induced transcriptional changes may provide further useful hints on the metabolic changes elicited by the sugar overfeeding [ 76 ].…”

Drosophila melanogaster as an alternative model organism in nutrigenomics

“…Diverse transcriptomic tools may be used in nutrigenomics research in Drosophila melanogaster including microarrays, to deliver information on changes in the mRNA expression following the dietary intake of a specific nutrient [7], and RNA sequencing [10] and next-generation sequencing (NGS) technologies [47], to analyze regions of interest in the genome, providing promising results and solutions to nutrigenomics studies by identifying new mutations in inbred fly strains. In addition, studies of QTL [48], representing a genome region that causes a significant variation in a quantitative trait, may be used in identifying signaling pathways involved in the metabolism of specific nutrients.…”

“…By comparing the intake of two different obesogenic diets, RNAseq analysis from Drosophila heads revealed significant differences in the transcriptome. While genes associated with immunity, metabolism, and hemocyanin have been mainly affected in flies fed with a high-fat diet, genes connected with cell cycle checkpoint kinases (CHK), cell cycle activity, and DNA binding and transcription have been upregulated in flies receiving a high-sugar diet [10]. In a recent study by Azuma and colleagues [55], plant bioactives have been applied to detect antiobesogenic effects in a fly model of obesity.…”

“…Particularly, due to the presence of a fat body with adipocytes and conserved metabolic pathways involved in fat metabolism and insulin signaling, Drosophila melanogaster has been extensively used to investigate obesity-associated diseases, including cardiovascular dysfunction or cancer [9][10][11]. Changes in triglyceride levels and lipid storage induced by the intake of high-fat and high-sugar diets have been related with genetic variations in both genes of the insulin/insulin-like growth factor signaling (IIS) and the target of rapamycin (TOR) signaling pathway [12,13].…”