Lipids, stored as triacylglycerol (TG), play an essential role as reserve of metabolic energy in insects. Utilization of fat body TG stores requires TG hydrolysis (lipolysis). Because fatty acids provide energy to other tissues as well as to the fat body cell, lipolysis must be coupled to multiple metabolic pathways. The long-term goal of this project is to understand the mechanism of regulation of lipolysis. During the previous period we identified two key components of the lipolytic pathway in insects. The main lipase found in the insect fat body, TG-lipase (TGL) homolog to Drosophila melanogaster CG8552, and a lipid droplet-associated protein, Lsd1, whose phosphorylation stimulates the rate of lipolysis. Lsd1 is one of the two PAT proteins, Lsd1 and Lsd2, of insect lipid droplets and plays a major role in the regulation of lipolysis. Lsd1 contains multiple conserved phosphorylation sites that regulate its activity. Lsd1 also has structurally conserved domains that are expected to play a role in its interaction with lipases and regulatory proteins and thus in the regulation of lipolysis. One of the goals of this project is to dissect the role of different regions of the Lsd1 molecule in the regulation of lipolysis. Other cytosolic and lipid droplet proteins, such as Lsd2, are expected to be involved in the regulation of lipolysis. This project also proposes to identify some of these proteins using a proteomic approach coupled to specific interaction assays and global studies to define differences in the protein composition of lipid droplets from several insects. Strong evidence indicating that the rate of lipolysis in the insect fat body is affected by the redox state of adipocytes led us to propose the investigation of this mechanism. Because the rate of TG hydrolysis must be modulated by signals originated from different pathways, we hypothesize that the redox state of the fat body cell, which is sensitive to multiple metabolic changes, plays a major role in the regulation of TG hydrolysis. In this project we will study the mechanism by which the redox state of the cell affects lipolysis. These studies will contribute to the understanding of the regulation of the utilization of energy stores in insects. This aspect of the biology of insects may be important to find mechanisms of control of insects that act as vectors of human diseases.

Public Health Relevance

Energy metabolism and its regulation are key processes defining insect survival and reproduction. TGs are the predominant form of energy storage in all animals. The ability to store and release this energy involves a carefully regulated balance between TG synthesis and hydrolysis. Specialized mechanisms are expected in insects, including vectors of human diseases, to meet their unique metabolic needs, such as the capacity to mobilize massive amounts of lipid in a short period of time. These metabolic distinctions must be reflected in the molecular mechanisms involved in TG mobilization in insects. The long term goal of this project is to achieve a clear understanding of the regulation of triacylglycerol metabolism in insects.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-IDM-M (02))
Program Officer
Chin, Jean
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Oklahoma State University Stillwater
Schools of Earth Sciences/Natur
United States
Zip Code
Leyria, Jimena; Fruttero, Leonardo L; Ligabue-Braun, Rodrigo et al. (2018) DmCatD, a cathepsin D-like peptidase of the hematophagous insect Dipetalogaster maxima (Hemiptera: Reduviidae): Purification, bioinformatic analyses and the significance of its interaction with lipophorin in the internalization by developing oocytes. J Insect Physiol 105:28-39
Chen, Xiao; Firdaus, Sarah J; Howard, Alisha D et al. (2017) Clues on the function of Manduca sexta perilipin 2 inferred from developmental and nutrition-dependent changes in its expression. Insect Biochem Mol Biol 81:19-31
Kanost, Michael R; Arrese, Estela L; Cao, Xiaolong et al. (2016) Multifaceted biological insights from a draft genome sequence of the tobacco hornworm moth, Manduca sexta. Insect Biochem Mol Biol 76:118-147
Soulages, Jose L; Wu, Zengying; Firdaus, Sarah J et al. (2015) Monoacylglycerol and diacylglycerol acyltransferases and the synthesis of neutral glycerides in Manduca sexta. Insect Biochem Mol Biol 62:194-210
Arrese, Estela L; Saudale, Fredy Z; Soulages, Jose L (2014) Lipid Droplets as Signaling Platforms Linking Metabolic and Cellular Functions. Lipid Insights 7:7-16
Wu, Zengying; Soulages, Jose L; Joshi, Bharat D et al. (2014) TGL-mediated lipolysis in Manduca sexta fat body: possible roles for lipoamide-dehydrogenase (LipDH) and high-density lipophorin (HDLp). Insect Biochem Mol Biol 45:58-68
Lin, Penghui; Chen, Xiao; Moktan, Hem et al. (2014) Membrane attachment and structure models of lipid storage droplet protein 1. Biochim Biophys Acta 1838:874-81
Soulages, Jose L; Firdaus, Sarah J; Hartson, Steve et al. (2012) Developmental changes in the protein composition of Manduca sexta lipid droplets. Insect Biochem Mol Biol 42:305-20
Arrese, Estela L; Soulages, Jose L (2010) Insect fat body: energy, metabolism, and regulation. Annu Rev Entomol 55:207-25
Arrese, Estela L; Howard, Alisha D; Patel, Rajesh T et al. (2010) Mobilization of lipid stores in Manduca sexta: cDNA cloning and developmental expression of fat body triglyceride lipase, TGL. Insect Biochem Mol Biol 40:91-9

Showing the most recent 10 out of 20 publications