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Mass spectroscopic analysis of phosphatidylinositol synthesis using 6-deuteriated-myo-inositol: comparison of the molecular specificities and acyl remodelling mechanisms in mouse tissues and cultured cells

Mass spectroscopic analysis of phosphatidylinositol synthesis using 6-deuteriated-myo-inositol: comparison of the molecular specificities and acyl remodelling mechanisms in mouse tissues and cultured cells
Mass spectroscopic analysis of phosphatidylinositol synthesis using 6-deuteriated-myo-inositol: comparison of the molecular specificities and acyl remodelling mechanisms in mouse tissues and cultured cells
Mammalian cell PtdIns (phosphatidylinositol) in vivo is enriched in the sn-1-stearoyl 2-arachidonoyl species, the physiological precursor of phosphatidylinositol 4,5-bisphosphate. Mechanisms regulating this specificity are unclear but are typically lost for cells in culture. We used ESI-MS (tandem electrospray ionization-mass spectrometry) to determine the molecular species of PtdIns synthesized by mouse tissues in vivo compared with cultured cells in vitro. After incorporation of deuteriated myo-d?-inositol over 3 h, endogenous and newly synthesized PtdIns and lysoPtdIns species were quantified from precursor scans of m/z 241? and m/z 247? respectively. PtdIns was synthesized as a wide range of species irrespective of the final membrane composition. Analyses of isotope enrichments argued against acyl remodelling as the major regulatory mechanism: composition of the lysoPtdIns pool under all conditions reflected that of either endogenous or newly synthesized PtdIns and was always at equilibrium. The kinetics of PtdIns synthesis, together with the prolonged time scale required for achieving final equilibrium compositions suggest that selective transport between membranes and/or hydrolysis of selected molecular species are the most probable mechanisms regulating compositions of PtdIns and, ultimately, phosphatidylinositol 4,5-bisphosphate.
acyl remodelling, cultured cells, lipidomics, molecular specificity, mouse tissues, phosphatidylinositol
0300-5127
1057-1059
Postle, A.D.
0fa17988-b4a0-4cdc-819a-9ae15c5dad66
Dombrowsky, H.
e1c360cd-147e-4ae7-bc57-b0d3a4cd2880
Clarke, H.
826e229e-4569-4500-853d-c73bd9bd9e3f
Pynn, C.J.
de6e8d3f-1161-4f9b-a1b1-6519965b01d1
Koster, G.
e404c38a-6f48-430a-adf0-5208228cb9e7
Hunt, A.N.
95a3e223-da96-40e7-b47d-27dce014e305
Postle, A.D.
0fa17988-b4a0-4cdc-819a-9ae15c5dad66
Dombrowsky, H.
e1c360cd-147e-4ae7-bc57-b0d3a4cd2880
Clarke, H.
826e229e-4569-4500-853d-c73bd9bd9e3f
Pynn, C.J.
de6e8d3f-1161-4f9b-a1b1-6519965b01d1
Koster, G.
e404c38a-6f48-430a-adf0-5208228cb9e7
Hunt, A.N.
95a3e223-da96-40e7-b47d-27dce014e305

Postle, A.D., Dombrowsky, H., Clarke, H., Pynn, C.J., Koster, G. and Hunt, A.N. (2004) Mass spectroscopic analysis of phosphatidylinositol synthesis using 6-deuteriated-myo-inositol: comparison of the molecular specificities and acyl remodelling mechanisms in mouse tissues and cultured cells. Biochemical Society Transactions, 32 (6), 1057-1059.

Record type: Article

Abstract

Mammalian cell PtdIns (phosphatidylinositol) in vivo is enriched in the sn-1-stearoyl 2-arachidonoyl species, the physiological precursor of phosphatidylinositol 4,5-bisphosphate. Mechanisms regulating this specificity are unclear but are typically lost for cells in culture. We used ESI-MS (tandem electrospray ionization-mass spectrometry) to determine the molecular species of PtdIns synthesized by mouse tissues in vivo compared with cultured cells in vitro. After incorporation of deuteriated myo-d?-inositol over 3 h, endogenous and newly synthesized PtdIns and lysoPtdIns species were quantified from precursor scans of m/z 241? and m/z 247? respectively. PtdIns was synthesized as a wide range of species irrespective of the final membrane composition. Analyses of isotope enrichments argued against acyl remodelling as the major regulatory mechanism: composition of the lysoPtdIns pool under all conditions reflected that of either endogenous or newly synthesized PtdIns and was always at equilibrium. The kinetics of PtdIns synthesis, together with the prolonged time scale required for achieving final equilibrium compositions suggest that selective transport between membranes and/or hydrolysis of selected molecular species are the most probable mechanisms regulating compositions of PtdIns and, ultimately, phosphatidylinositol 4,5-bisphosphate.

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More information

Published date: 2004
Additional Information: Researd colloquia at BioScience 2004
Keywords: acyl remodelling, cultured cells, lipidomics, molecular specificity, mouse tissues, phosphatidylinositol

Identifiers

Local EPrints ID: 27335
URI: http://eprints.soton.ac.uk/id/eprint/27335
ISSN: 0300-5127
PURE UUID: 68d594c3-bc59-4ee8-a780-b6deed74537f
ORCID for A.D. Postle: ORCID iD orcid.org/0000-0001-7361-0756
ORCID for A.N. Hunt: ORCID iD orcid.org/0000-0001-5938-2152

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Date deposited: 27 Apr 2006
Last modified: 09 Jan 2022 02:47

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Contributors

Author: A.D. Postle ORCID iD
Author: H. Dombrowsky
Author: H. Clarke
Author: C.J. Pynn
Author: G. Koster
Author: A.N. Hunt ORCID iD

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