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First published online 1 November 2006
doi: 10.1242/dev.02659

Development 133, 4731-4735 (2006)
Published by The Company of Biologists 2006
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Cytoplasmic activated protein kinase Akt regulates lipid-droplet accumulation in Drosophila nurse cells

Natalia Vereshchagina and Clive Wilson*

Department of Physiology, Anatomy and Genetics, Le Gros Clark Building, University of Oxford, South Parks Road, Oxford OX1 3QX, UK.

* Author for correspondence (e-mail: clive.wilson{at}anat.ox.ac.uk)

Accepted 25 September 2006

The insulin/insulin-like growth factor signalling (IIS) cascade performs a broad range of evolutionarily conserved functions, including the regulation of growth, developmental timing and lifespan, and the control of sugar, protein and lipid metabolism. Recently, these functions have been genetically dissected in the fruit fly Drosophila melanogaster, revealing a crucial role for cell-surface activation of the downstream effector kinase Akt in many of these processes. However, the mechanisms regulating lipid metabolism and the storage of lipid during development are less well characterized. Here, we use the nutrient-storing nurse cells of the fly ovary to study the cellular effects of intracellular IIS components on lipid accumulation. These cells normally store lipid in a perinuclear pool of small neutral triglyceride-containing droplets. We find that loss of the IIS signalling antagonist PTEN, which stimulates cell growth in most developing tissues, produces a very different phenotype in nurse cells, inducing formation of highly enlarged lipid droplets. Furthermore, we show that the accumulation of activated Akt in the cytoplasm is responsible for this phenotype and leads to a much higher expression of LSD2, the fly homologue of the vertebrate lipid-storage protein perilipin. Our work therefore reveals a signalling mechanism by which the effect of insulin on lipid metabolism could be regulated independently of some of its other functions during development and adulthood. We speculate that this mechanism could be important in explaining the well-established link between obesity and insulin resistance that is observed in Type 2 diabetes.

Key words: Drosophila, Insulin, PTEN, Obesity, Oogenesis




This article has been cited by other articles:


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 J. Cell Sci.Home page
N. Vereshchagina, M.-C. Ramel, E. Bitoun, and C. Wilson
The protein phosphatase PP2A-B' subunit Widerborst is a negative regulator of cytoplasmic activated Akt and lipid metabolism in Drosophila
J. Cell Sci., October 15, 2008; 121(20): 3383 - 3392.
[Abstract] [Full Text] [PDF]


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