A quantitative characterisation of phospholipid composition and biosynthesis in HeLa cells and nuclei - a mass spectrometry study

Abstract

Nuclei from Human cells have been shown to contain a pool of endonuclear phospholipidthat is distinct from the nuclear membrane. It has been suggested that this endonuclear phospholipid is involved in the regulation of nuclear processes such as transcription. This study utilised tandem electrospray ionisation mass spectrometry to determine, quantitatively, the phospholipid content of cultured HeLa (Human cervical carcinoma) cells and their isolated naked nuclei. Endonuclear PC, DAG and PI was found to be enriched in disaturated molecular species with respect to the whole cell.Whole cell and endonuclear phospholipid content was monitored throughout the cell cycle following treatment with the cell cycle blocking agent mimosine. The molecular species composition of both whole cell and nuclei was found to differ to that of cells which had not been treated with mimosine. These compositions and differences between synchronous and asynchronous cell populations were found to relate to the saturation level of the molecular species. Using a combination of ESI-MS and stable isotope labelling, the biosynthesis of PC was monitored in both whole cells and nuclei. The molecular species composition of newly synthesised PC closely resembled that of endogenous PC. Biosynthesis of PC was found to continue in nuclei that had been removed from the cell and stripped of their nuclear envelope

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ORCID for George S. Attard: orcid.org/0000-0001-8304-0742

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