Recently the presence of phosphoinositides (PIPns) in the eukaryotic cell nucleoplasm and nuclear membrane has been described (1). We have studied the interaction of the nuclear proteins, histones, with these lipids in model membranes. Turbidimetric studies revealed that histones induce extensive aggregation of vesicles when containing phosphatidylinositol-4-phosphate (PtdIns(4)P) and in a smaller extent when containing phosphatidylinositol (PtdIns). Binding and aggregation events were visualized by confocal microscopy. Using isothermal calorimetry we determined that the binding of histone H1 to PtdIns(4)P was one order of magnitude higher than with PtdIns.
Intervesicular mixing of total lipids and inner monolayer lipids was found in vesicles containing PtdIns(4)P, but not on those containing PtdIns. Supporting our hypothesis about the role histones could play promoting fusion events.
Taking this together we suggest that a complex interplay of histones and phosphoinositides could be taking place in the nucleoplasm where histones could have an important role during the remodeling processes of the mitotic cell cycle.
- Byrne, R. D., M. Garnier-Lhomme, K. Han, M. Dowicki, N. Michael, N. Totty, V. Zhendre, A. Cho, T. R. Pettitt, M. J. Wakelam, D. L. Poccia, and B. Larijani. 2007. PLCgamma is enriched on poly-phosphoinositide-rich vesicles to control nuclear envelope assembly. Cellular signalling 19:913-922.