Nuclear lipid microdomains regulate cell function.

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-synthase 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.