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| Current Research Project(s) Descriptions | |
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Project I |
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Phospholipase Activation by G-Protein-Linked Receptors |
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This project is focused on the mechanism of activation of PLD1 by the monomeric GTPase Cdc42 and its function in the cell. The project seeks to extend previous studies by exploring the functional connections between the Cdc42-PLD pathway to cell survival via the mTOR pathway, production of extracellular survival factors, and defining the signal transduction pathways of P2Y receptors to PLD and the role of phosphatidic acid in promotion of cell proliferation and survival. |
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Project II |
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The primary goal of the Alliance for Cellular Signaling is to determine how cells process information in a context dependent manner. A variety of single and dual ligand screens are being conducted in RAW264.7 macrophages using a wide variety of techniques, including our Lipidomic Laboratory, in order to create a comprehensive cell signaling map. The emphasis of the next five years is to develop a mathematical model of "signaling nodes" that incorporate lipid second messengers into the complex integrative processes that control cellular outcomes. |
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Project III |
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The goals of the LIPID MAPS project include separation and detection of the lipid species that compromise the RAW264.7 and primary mouse macrophage, development of quantitative analysis of lipid metabolites, analysis of changes in lipid composition as a function of stimulation (e.g., LPS treatment), and defining the pathways of integration between different classes of biological lipids in macrophages. The primary emphases of this project are (1) extending the technology of analytical, quantitative determination of cellular lipid composition by liquid chromatography- mass spectrometry (LC-MS) (2) determination of the lipid composition of a specified cell, and (3) to define biosynthetic pathways for each lipid and develop lipid maps that define interaction networks. |
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| Project IV | |
| National Cancer Institute (NCI) | |
Lipid Profiling in Mammary Carcinomas |
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This one year pilot grant seeks to establish conditions for developing a lipid profiling methodology in breast cancer derived cells and tumors. |
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| Project V | |
Lipid Pathway Regulation of Vesicular Trafficking. |
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| Background: There are several hundred, more likely thousands, of molecular species of lipids in eukaryotic cells. Within but one class of cellular lipids, the glycerophospholipids, there are a large assortment of polar headgroups (e.g., inositol and choline) that contain an array of possible combinations of fatty acid chain lengths and degrees of desaturation within each of the classifications. The goal of this project is to better understand the regulation of mammalian phospholipases and glycerophospholipid derived lipid second messenger production in mast cell degranulation. Changes in lipid composition are associated with membrane remodeling processes, such as vesicle biogenesis, endocytosis, and regulated exocytosis (called degranulation in mast cells). In some cell types, the binding of hormones and antigens to cell surface receptors stimulate phospholipases and initiate regulated secretion. Although there is extensive literature on the effects of lipid composition on vesicle mixing rates in vitro , little is known about the functional interconnection between these observed accelerated rates of model membrane fusion and physiological secretory granule fusion in cells. The working hypothesis is that the regulated metabolism of phospholipids plays a major role in the biochemical processes that lead to degranulation. With our collaborators we will take advantage of four systems to explore the role of bioactive lipids in trafficking and exocytosis. These include yeast and Drosophila , which are excellent genetic systems for the molecular dissection of these processes, as well as adrenal chromaffin cells (rapid release of secreted contents from an excitable cell) and mast cells (long sustained release triggered by secretagogues). The central questions of this effort include: (1) Specifically, does phospholipase D (PLD) play an essential role in mast cell degranulation? (2) Are unique lipids generated (or consumed) in receptor-mediated degranulation in mast cells? (3) Do the modulators of PLD activity (e.g., Arf6, Cdc42, G βγ subunits, and PIP2) and the formation of an isolated subset of lipid second messengers promote secretion? (4) Can we identify the specific lipid changes in membrane lipid composition that promote exocytosis in intact cells as well as analyzing lipid changes in isolated subcellular components, such as secretory vesicles and plasma membranes to better understand the dynamic roles that lipids play in secretory and trafficking processes? This project seeks to explore the dynamic roles of lipids in the biochemical basis of regulated secretion. We have chosen mast cells as a model system, because of their importance in immune and allergic functions. In addition, regulated secretion in mast cells can be recovered in broken cell preparations allowing access to intracellular membranes. |
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