Nuclear Lipid Signaling

Robin F. Irvine^*

Department of Pharmacology, University of Cambridge, Cambridge CB2 1QJ, UK.

Gloss: The eukaryotic nucleus is surrounded by a double membrane that can be regarded as a specialized part of the endoplasmic reticulum, so it is no surprise that lipids are present in nuclei, and that these can change under some conditions. However, what is surprising is that if the nuclear membrane is removed by detergents, there remains a considerable amount of lipid and lipid-synthesizing and metabolizing enzymes. These enzymes are undoubtedly intranuclear, and they 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 [PtdIns(4,5)P₂]. This PtdIns(4,5)P₂ can in turn be hydrolyzed to diacylglycerol (DAG) by a phospholipase C (PI-PLC) that is regulated separately from the "classic" plasma membrane PI-PLC. This nuclear DAG can recruit protein kinase C from the cytoplasm to the nucleus to phosphorylate substrates, most of which are still unidentified. However, that cycle is only the tip of the iceberg, 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 and 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.

*Contact information. E-mail, rfi20{at}cam.ac.uk

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PERSPECTIVES
Nuclear Signaling
Stress-ING Out: Phosphoinositides Mediate the Cellular Stress Response

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Sci. STKE 2006 (360), pe46. [DOI: 10.1126/stke.3602006pe46]
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APOPTOSIS
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(24 May 2005)
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REVIEWS
Nuclear Lipid Signaling

Robin Irvine (5 September 2000)
Sci. STKE 2000 (48), re1. [DOI: 10.1126/stke.2000.48.re1]
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