The functional organisation of promyelocytic leukaemia nuclear bodies in human interphase cells

• Main Author: Wang, Jayson Ee Hur
• Published: University College London (University of London) 2005
• Subjects: 616.99419
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417135

Promyelocytic leukaemia (PML) nuclear bodies are nuclear structures found in a variety of normal tissues and cell lines. They have been implicated in diverse human diseases. In particular, the major constituent, the PML protein, forms a fusion product with another protein in acute promyelocytic leukaemia (APL). These bodies however, also recruit over thirty different proteins with disparate functions. As such, no definite role of these bodies has been discovered, although proposed functions include gene transcription, cell cycle control and deoxyribonucleic acid (DNA) repair. This thesis describes the association of PML bodies with different genomic loci, using principally confocal microscopy and a novel statistical model. The aim was to use such associations to determine if a functional basis exists for the intranuclear pattern of PML bodies. By analyzing loci-PML body distances for different gene loci, it was found that the distance between a locus and its nearest PML body correlates with the transcriptional activity and gene density around the locus. This was confirmed when regions of specific gene activation were examined. However, using RNA-FISH (ribonucleic acid- fiuorescence in situ hybridisation) methodology and RNA interference (RNAi) knockdown studies, PML bodies were found not to be directly involved in gene transcription. Furthermore, cells in S-phase were examined in more detail, and it was found that PML bodies also associated statistically with actively replicating loci. The experiments performed suggest a non-random and functional basis for the positioning of PML bodies. This thesis proposes that PML bodies are multifunctional structures that lie predominantly in nuclear compartments of high transcriptional activity, although they also associate with regions of DNA replication. Finally, this work strengthens the model of the nucleus as a highly organised structure.