Mobilization of Triacylglycerol Stores in Insects

Summary

Principal Investigator: ESTELA ARRESE
Affiliation: Oklahoma State University
Country: USA
Abstract: DESCRIPTION: (provided by the applicant): Unlike vertebrates, where the stored fatty acids are mobilized as free fatty acids, a great number of insects, mobilizes fatty acids as an-1, 2-diacylglycerol (DG). The mobilization of TG stores requires the action of a TG-lipase, whose activity is hormonally regulated. The substrate of the lipase (TG) is found in large intracellular lipid droplets, which are constituted by a core of TG surrounded by a complex surface layer of phospholipids and proteins. On the other hand, the TG-lipase localizes in the cytosol of lipolytically unstimulated fat body cells. Lipolysis involves the interaction of the lipase with the surface of the lipid droplet. It is known that activation of lipolysis promotes both an increase of intracellular calcium concentration and activation of amp-dependent protein kinase (A-kinase) but the basic mechanisms involved in how phosphorylation-dephosphorylation reactions modulate the rate of lipolysis is unknown. Moreover, little is known about the relevance and nature of the structural and compositional changes that affect the lipid droplet when lipolysis is hormonally activated. These changes must ultimately affect the interaction of the lipase with the lipid substrate and the concomitant activation of lipolysis. DG moves from the lipid droplet to the plasma membrane by an uncharacterized mechanism. It appears that after the conversion of TG into DG on the surface of the lipid droplets, DG would be transferred to a cytosolic carrier, which in turn would target the delivery of DG across the plasma membrane. The overall goals of this project are to establish the mechanisms regulating lipolysis by determining the factors that promotes the interaction between TG-lipase and its substrate, the lipid droplet and to define the mechanism of intracellular transport of DG. Clearly the elucidation of these mechanisms is of fundamental importance in insect biochemistry and physiology. These studies will provide comprehensive information on the lipolytic process in insects and this knowledge could also contribute to the broad field of lipid metabolism and transport in vertebrates.
Funding Period: 2002-02-01 - 2008-01-31
more information: NIH RePORT

Top Publications

  1. ncbi Activation of the lipid droplet controls the rate of lipolysis of triglycerides in the insect fat body
    Rajesh T Patel
    Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, 74078, USA
    J Biol Chem 280:22624-31. 2005
  2. ncbi Adipokinetic hormone-induced mobilization of fat body triglyceride stores in Manduca sexta: role of TG-lipase and lipid droplets
    Rajesh T Patel
    Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
    Arch Insect Biochem Physiol 63:73-81. 2006
  3. ncbi The main triglyceride-lipase from the insect fat body is an active phospholipase A(1): identification and characterization
    Estela L Arrese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
    J Lipid Res 47:2656-67. 2006
  4. ncbi Stimulation of lipolysis enhances the rate of cholesterol efflux to HDL in adipocytes
    Philip B Verghese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, 147 Noble Research Center, Stillwater, OK 74078, USA
    Mol Cell Biochem 302:241-8. 2007
  5. ncbi Function and structure of lipid storage droplet protein 1 studied in lipoprotein complexes
    Estela L Arrese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, 246 Noble Research Center, Stillwater, OK 74078, USA
    Arch Biochem Biophys 473:42-7. 2008
  6. ncbi Expression of lipid storage droplet protein-1 may define the role of AKH as a lipid mobilizing hormone in Manduca sexta
    Estela L Arrese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, 246 Noble Research Center, Stillwater, OK 74078, USA
    Insect Biochem Mol Biol 38:993-1000. 2008
  7. ncbi Purification and characterization of recombinant lipid storage protein-2 from Drosophila melanogaster
    Estela L Arrese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
    Protein Pept Lett 15:1027-32. 2008
  8. ncbi Insect fat body: energy, metabolism, and regulation
    Estela L Arrese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74074, USA
    Annu Rev Entomol 55:207-25. 2010

Scientific Experts

  • E L Arrese
  • Rajesh T Patel
  • Jose L Soulages
  • Philip B Verghese
  • Balaji Hariharasundaram

Detail Information

Publications8

  1. ncbi Activation of the lipid droplet controls the rate of lipolysis of triglycerides in the insect fat body
    Rajesh T Patel
    Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, 74078, USA
    J Biol Chem 280:22624-31. 2005
    ..This activation is achieved by PKA-mediated phosphorylation of the lipid droplet. Lsdp1 is the main target of PKA, suggesting that this protein is a major player in the activation of lipolysis in insects...
  2. ncbi Adipokinetic hormone-induced mobilization of fat body triglyceride stores in Manduca sexta: role of TG-lipase and lipid droplets
    Rajesh T Patel
    Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
    Arch Insect Biochem Physiol 63:73-81. 2006
    ..However, the phosphorylation level of the TG-lipase was unchanged by AKH, indicating that phosphorylation of the TG-lipase plays no role in the activation of lipolysis induced by AKH...
  3. ncbi The main triglyceride-lipase from the insect fat body is an active phospholipase A(1): identification and characterization
    Estela L Arrese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
    J Lipid Res 47:2656-67. 2006
    ..These results suggest that the PL activity of the insect TG-lipase could be required to allow access of the lipase to TG molecules contained in the core of the lipid droplets...
  4. ncbi Stimulation of lipolysis enhances the rate of cholesterol efflux to HDL in adipocytes
    Philip B Verghese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, 147 Noble Research Center, Stillwater, OK 74078, USA
    Mol Cell Biochem 302:241-8. 2007
    ..The study supports a metabolic link between the lipolytic activity of adipocytes and the rate of cellular cholesterol efflux to HDL...
  5. ncbi Function and structure of lipid storage droplet protein 1 studied in lipoprotein complexes
    Estela L Arrese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, 246 Noble Research Center, Stillwater, OK 74078, USA
    Arch Biochem Biophys 473:42-7. 2008
    ..7-fold activation of the main fat body lipase demonstrating the direct link between Lsd1 phosphorylation and activation of lipolysis. Serine 20 was identified as the Lsd1-phosphorylation site triggering this effect...
  6. ncbi Expression of lipid storage droplet protein-1 may define the role of AKH as a lipid mobilizing hormone in Manduca sexta
    Estela L Arrese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, 246 Noble Research Center, Stillwater, OK 74078, USA
    Insect Biochem Mol Biol 38:993-1000. 2008
    ..Lsd1 was found in the fat body but it was undetectable in lipid droplets isolated from oocytes or embryos. The present study suggests a link between AKH-stimulated lipolysis in the fat body and the expression of Lsd1...
  7. ncbi Purification and characterization of recombinant lipid storage protein-2 from Drosophila melanogaster
    Estela L Arrese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
    Protein Pept Lett 15:1027-32. 2008
    ..This study provides the starting point for future studies on the mechanism of function of Lsd2. The similarities and differences between Lsd1 and Lsd2, the only PAT proteins found in insects, are discussed...
  8. ncbi Insect fat body: energy, metabolism, and regulation
    Estela L Arrese
    Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74074, USA
    Annu Rev Entomol 55:207-25. 2010
    ..This review focuses on energy storage and release and summarizes current understanding of the mechanisms underlying these processes in insects...