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Highly saturated endonuclear phosphatidylcholine is synthesized in situ and colocated with CDP-choline pathway enzymes

Highly saturated endonuclear phosphatidylcholine is synthesized in situ and colocated with CDP-choline pathway enzymes
Highly saturated endonuclear phosphatidylcholine is synthesized in situ and colocated with CDP-choline pathway enzymes
Chromatin-associated phospholipids are well recognized. A report that catalytically active endonuclear CTP:choline-phosphate cytidylyltransferase alpha is necessary for cell survival questions whether endonuclear, CDP-choline pathway phosphatidylcholine synthesis may occur in situ. We report that chromatin from human IMR-32 neuroblastoma cells possesses such a biosynthetic pathway. First, membrane-free nuclei retain all three CDP-choline pathway enzymes in proportions comparable with the content of chromatin-associated phosphatidylcholine. Second, following supplementation of cells with deuterated choline and using electrospray ionization mass spectrometry, both the time course and molecular species labeling pattern of newly synthesized endonuclear and whole cell phosphatidylcholine revealed the operation of spatially separate, compositionally distinct biosynthetic routes. Specifically, endogenous and newly synthesized endonuclear phosphatidylcholine species are both characterized by a high degree of diacyl/alkylacyl chain saturation. This unusual species content and synthetic pattern (evident within 10 min of supplementation) are maintained through cell growth arrest by serum depletion and when proliferation is restored, suggesting that endonuclear disaturated phosphatidylcholine enrichment is essential and closely regulated. We propose that endonuclear phosphatidylcholine synthesis may regulate periodic nuclear accumulations of phosphatidylcholine-derived lipid second messengers. Furthermore, our estimates of saturated phosphatidylcholine nuclear volume occupancy of around 10% may imply a significant additional role in regulating chromatin structure.
ctp-phosphocholine cytidylyltransferase, protein-kinase-c, chromatin phospholipids, nuclear phospholipids, mass-spectrometry, friend-cells, rat, diacylglycerol, association, contain
0021-9258
8492-8499
Hunt, Alan N.
95a3e223-da96-40e7-b47d-27dce014e305
Clark, Graeme T.
1ccb751b-3780-485a-b1de-07bbee387859
Attard, George S.
3219075d-2364-4f00-aeb9-1d90f8cd0d36
Postle, Anthony D.
0fa17988-b4a0-4cdc-819a-9ae15c5dad66
Hunt, Alan N.
95a3e223-da96-40e7-b47d-27dce014e305
Clark, Graeme T.
1ccb751b-3780-485a-b1de-07bbee387859
Attard, George S.
3219075d-2364-4f00-aeb9-1d90f8cd0d36
Postle, Anthony D.
0fa17988-b4a0-4cdc-819a-9ae15c5dad66

Hunt, Alan N., Clark, Graeme T., Attard, George S. and Postle, Anthony D. (2001) Highly saturated endonuclear phosphatidylcholine is synthesized in situ and colocated with CDP-choline pathway enzymes. The Journal of Biological Chemistry, 276 (11), 8492-8499. (doi:10.1074/jbc.M009878200).

Record type: Article

Abstract

Chromatin-associated phospholipids are well recognized. A report that catalytically active endonuclear CTP:choline-phosphate cytidylyltransferase alpha is necessary for cell survival questions whether endonuclear, CDP-choline pathway phosphatidylcholine synthesis may occur in situ. We report that chromatin from human IMR-32 neuroblastoma cells possesses such a biosynthetic pathway. First, membrane-free nuclei retain all three CDP-choline pathway enzymes in proportions comparable with the content of chromatin-associated phosphatidylcholine. Second, following supplementation of cells with deuterated choline and using electrospray ionization mass spectrometry, both the time course and molecular species labeling pattern of newly synthesized endonuclear and whole cell phosphatidylcholine revealed the operation of spatially separate, compositionally distinct biosynthetic routes. Specifically, endogenous and newly synthesized endonuclear phosphatidylcholine species are both characterized by a high degree of diacyl/alkylacyl chain saturation. This unusual species content and synthetic pattern (evident within 10 min of supplementation) are maintained through cell growth arrest by serum depletion and when proliferation is restored, suggesting that endonuclear disaturated phosphatidylcholine enrichment is essential and closely regulated. We propose that endonuclear phosphatidylcholine synthesis may regulate periodic nuclear accumulations of phosphatidylcholine-derived lipid second messengers. Furthermore, our estimates of saturated phosphatidylcholine nuclear volume occupancy of around 10% may imply a significant additional role in regulating chromatin structure.

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More information

Published date: 2001
Keywords: ctp-phosphocholine cytidylyltransferase, protein-kinase-c, chromatin phospholipids, nuclear phospholipids, mass-spectrometry, friend-cells, rat, diacylglycerol, association, contain

Identifiers

Local EPrints ID: 27164
URI: http://eprints.soton.ac.uk/id/eprint/27164
ISSN: 0021-9258
PURE UUID: cea61689-86c8-4612-b647-c6e8319f55ef
ORCID for Alan N. Hunt: ORCID iD orcid.org/0000-0001-5938-2152
ORCID for George S. Attard: ORCID iD orcid.org/0000-0001-8304-0742
ORCID for Anthony D. Postle: ORCID iD orcid.org/0000-0001-7361-0756

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Date deposited: 26 Apr 2006
Last modified: 31 Jul 2019 00:55

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Contributors

Author: Alan N. Hunt ORCID iD
Author: Graeme T. Clark

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