The evidence accumulated in recent years on the presence of phospholipids inside the interphase nucleus needs a precise localization of the nuclear sites of accumulation, transport and degradation of these molecules. A very useful approach for monitoring the fine localization of nuclear phospholipids is represented by a recently developed technique using gold-conjugated phospholipases. In fact, in addition to the phospholipids organized in bilayers in the membrane, this technique identifies amorphous lipoprotein complexes present in different celi areas as well as in the nucleus. In this way and using sample preparation systems which reduce lipid removal and translocation, such as cryofixation, cryosectioning, embedding in hydrophylic resins and cryofracturing, we have analyzed the subnuclear localization of phospholipids in different experimental conditions. The results indicate that: in interphase the nuclear phospholipids are localized mainly in the interchromatin spaces and in the nucleolar domain; the observed co-localization of phospholipids and ribonucleoproteins suggests that phospholipids are involved in the mechanism of transport and release of the transcripts; the demonstrated release of ribonucleoproteins after phospholipase digestion suggests that phospholipids mediate the binding between ribonucleoproteins and the nuclear matrix; significant changes of the phospholipid localization occur in the different phases of the celi cycle or in the course of induced celi differentiation.
Morphological evidence of function-related localization of phospholipids in the cell nucleus.
CAPITANI, Silvano;
1992
Abstract
The evidence accumulated in recent years on the presence of phospholipids inside the interphase nucleus needs a precise localization of the nuclear sites of accumulation, transport and degradation of these molecules. A very useful approach for monitoring the fine localization of nuclear phospholipids is represented by a recently developed technique using gold-conjugated phospholipases. In fact, in addition to the phospholipids organized in bilayers in the membrane, this technique identifies amorphous lipoprotein complexes present in different celi areas as well as in the nucleus. In this way and using sample preparation systems which reduce lipid removal and translocation, such as cryofixation, cryosectioning, embedding in hydrophylic resins and cryofracturing, we have analyzed the subnuclear localization of phospholipids in different experimental conditions. The results indicate that: in interphase the nuclear phospholipids are localized mainly in the interchromatin spaces and in the nucleolar domain; the observed co-localization of phospholipids and ribonucleoproteins suggests that phospholipids are involved in the mechanism of transport and release of the transcripts; the demonstrated release of ribonucleoproteins after phospholipase digestion suggests that phospholipids mediate the binding between ribonucleoproteins and the nuclear matrix; significant changes of the phospholipid localization occur in the different phases of the celi cycle or in the course of induced celi differentiation.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
