H. Alex Brown
Principle Investigator; Professor of Pharmacology, Chemistry, and Biochemistry; Associate Director, VICB;
Last active: 2/12/2015

Electrospray ionization mass spectrometry analysis of changes in phospholipids in RBL-2H3 mastocytoma cells during degranulation.

Ivanova PT, Cerda BA, Horn DM, Cohen JS, McLafferty FW, Brown HA
Proc Natl Acad Sci U S A. 2001 98 (13): 7152-7

PMID: 11416200 · PMCID: PMC34638 · DOI:10.1073/pnas.131195098

Biological membranes contain an extraordinary diversity of lipids. Phospholipids function as major structural elements of cellular membranes, and analysis of changes in the highly heterogeneous mixtures of lipids found in eukaryotic cells is central to understanding the complex functions in which lipids participate. Phospholipase-catalyzed hydrolysis of phospholipids often follows cell surface receptor activation. Recently, we demonstrated that granule fusion is initiated by addition of exogenous, nonmammalian phospholipases to permeabilized mast cells. To pursue this finding, we use positive and negative mode Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) to measure changes in the glycerophospholipid composition of total lipid extracts of intact and permeabilized RBL-2H3 (mucosal mast cell line) cells. The low energy of the electrospray ionization results in efficient production of molecular ions of phospholipids uncomplicated by further fragmentation, and changes were observed that eluded conventional detection methods. From these analyses we have spectrally resolved more than 130 glycerophospholipids and determined changes initiated by introduction of exogenous phospholipase C, phospholipase D, or phospholipase A2. These exogenous phospholipases have a preference for phosphatidylcholine with long polyunsaturated alkyl chains as substrates and, when added to permeabilized mast cells, produce multiple species of mono- and polyunsaturated diacylglycerols, phosphatidic acids, and lysophosphatidylcholines, respectively. The patterns of changes of these lipids provide an extraordinarily rich source of data for evaluating the effects of specific lipid species generated during cellular processes, such as exocytosis.

MeSH Terms (16)

Animals Cell Degranulation Cell Membrane Permeability Fourier Analysis Mass Spectrometry Mast-Cell Sarcoma Phosphatidylcholines Phospholipase D Phospholipases A Phospholipases A2 Phospholipids Rats Spectrometry, Mass, Electrospray Ionization Substrate Specificity Tumor Cells, Cultured Type C Phospholipases

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