Nuclear lipid microdomains regulate cell function

Abstract

The lipids present in the nuclei play different roles in relation to their localization. They are composed by high levels of phosphatidylcholine and sphingomyelin strongly linked with cholesterol. The nuclear lipid composition shows many modifications during cell life due to the presence and activity of some specific enzymes such as sphingomyelinase, sphingomyelin-synthase, reverse sphingomyelin-syntase and phosphatidylcholine-specific phospholipase C. These lipids are associated with a small amount of DNA, with the new-synthesized double-strand RNA, and with proteins to form an intranuclear complex that it is not possible to extract with the techniques used for nuclear membrane and chromatin purification. The intranuclear complex represents a section of inner nuclear membrane that binds to the active chromatin. In a recent paper, we have demonstrated that this complex actually constitutes the lipid microdomains present in the inner nuclear membrane and represents a platform for the transcription process. The possible model of action is reported in this addendum article.

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Acknowledgements

We wish to acknowledge support from Ministero dell' Università e Ricerca (PRIN project), ASI (Agenzia Spaziale Italiana), and the Fondazione Cassa di Risparmio di Perugia. We also thank Remo Lazzarini for the technical assistance, and Ryan Rhome for the manuscript revision.

Figures and Tables

Figure 1 Nuclear lipid microdomains as platform for the transcription process: a model. CHO, cholesterol; Cr, chromatin; INM, inner nuclear membrane; PC, phosphatidylcholine; PPC, phosphocholine; SM, sphingomyelin; SMase, sphingomyelinase; SM-synthase, sphingomyelin-synthase.

Addendum to: