Nuclear Lipid Signaling

Robin Irvine

The author is in the Department of Pharmacology, University of Cambridge, Cambridge CB2 1QJ, UK. E-mail: rfi20{at}cam.ac.uk

The eukaryotic nucleus is surrounded by a double membrane that can be regarded as a part of the endoplasmic reticulum, albeit a specialized part, so it is no particular surprise that lipids are present in nuclei, and that these can change under some conditions. However, what is surprising to many people is that if the nuclear membrane is removed by detergents, there is still a considerable amount of lipid left, and a large number of lipid-synthesizing and metabolizing enzymes. These enzymes are undoubtedly intranuclear, and cannot be discounted as arising from contamination with other cellular fractions. The best characterized of these enzymes are the components of a nuclear polyphosphoinositide cycle that generates phosphatidylinositol-4,5-bisphosphate [PIP₂ or PtdIns(4,5)P₂]. This PIP₂ can in turn be hydrolyzed to diacylglycerol by a phospholipase C (PI-PLC) that is regulated separately from the "classic" plasma membrane PI-PLC. This nuclear diacylglycerol can recruit protein kinase C to the nucleus to phosphorylate substrates (mostly) as yet unidentified. However, that cycle is only the tip of the iceberg, and more and more lipid signaling pathways and players are being implicated as existing within the nucleus. This is a large and confusing literature. This review focuses on the main issues critically assesses the best evidence for what is and is not truly nuclear lipid signaling, and for what such signaling may or may not do.

Citation:
Irvine,R. (2000) Nuclear Lipid Signaling.
Science's STKE: http://www.stke.org/cgi/content/full/OC_sigtrans;2000/48/re1

© 2000 American Association for the Advancement of Science

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Nuclear Lipid Signaling

Robin F. Irvine (17 September 2002)
Sci. STKE 2002 (150), re13. [DOI: 10.1126/stke.2002.150.re13]
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