Nuclear bodies: multifaceted subdomains of the interchromatin space

A Direct Interaction between the Survival Motor Neuron Protein and p53 and Its Relationship to Spinal Muscular Atrophy

“…These bodies also contained Sm core proteins and U1 snRNP auxillary factor (U1A) (24). An average mammalian cell contains 10 -20 PML bodies, and these bodies dissociate in cells from human acute promyelocytic leukemia patients (6,37). In a broad number of cell lines and in differentiated adult mammalian tissue, SMN and p80 coilin colocalize in another class of nuclear bodies termed Cajal bodies (31,38).…”

Dual role for the RNA-binding domain of Xenopus laevis SLBP1 in histone pre-mRNA processing

“…In the cell, much of the U7 snRNP is found in Cajal (coiled) bodies, "spheres" in Xenopus oocytes (Wu & Gall, 1993;Wu et al+, 1996), and these nuclear organelles are located near the histone genes in oocytes (Callan et al+, 1991) and in mammalian cells (Frey & Matera, 1995;Matera, 1999), suggesting a role for the coiled bodies in histone pre-mRNA processing+ Some of the xSLBP1 in the frog oocyte is also located in the spheres (Abbott et al+, 1999)+ One possibility is that xSLBP1 may function in a distinct subnuclear compartment+ The histone genes have remained tightly clustered throughout evolution, suggesting that there is selective pressure keeping them closely linked (Wang et al+, 1996a(Wang et al+, , 1996b)+ One reason for this tight clustering may be that the genes are localized in a region of the nucleus specific for histone mRNA processing+ Ninety-five percent of the U7 snRNA in the Xenopus oocyte nucleus is present in spheres (Wu & Gall, 1993)+ Spheres are found dispersed in the nucleoplasm and some are physically attached to the chromosomes at histone gene loci in amphibian oocyte lampbrush chromosome spreads (Callan et al+, 1991)+ Recently Gall and coworkers have shown that xSLBP1 is present in the spheres of the amphibian germinal vesicle (Abbott et al+, 1999)+ A region of xSLBP1, including part of the RBD and the C-terminal region, is capable of directing the xSLBP1 to coiled bodies (Abbott et al+, 1999)+ The spheres also contain RNA polymerase II and coilin (Bellini & Gall, 1998), which has also been shown to associate with the U7 snRNP (Bellini & Gall, 1998)+ Localization of xSLBP1 to the spheres (coiled bodies) may be important for efficient histone pre-mRNA processing in vivo+ The 1-2-1 protein may be deficient in localizing to the coiled bodies or may not interact with unknown factor(s) necessary for processing in vivo, but not in vitro+ In nuclear extracts, any nuclear substructures are disrupted allowing interaction of factors that may be physically separated in the nucleus in vivo+ It is also likely that histone premRNA processing is coupled to histone gene transcription in vivo, as is polyadenylation (McCracken et al+, 1997)+ Thus in vivo there may be a defined pathway by which the histone pre-mRNA processing machinery is assembled and this pathway could be disrupted in nuclear extracts+ Differences in metabolism of the same RNA molecule transcribed from a gene and injected into the nucleoplasm are likely to be observed in many cases+ Differences in the "masking" of mRNAs have been observed in Xenopus oocytes depending on whether synthetic pre-mRNA was injected or whether the premRNA was expressed from an injected gene (Meric et al+, 1996;Matsumoto et al+, 1998)+ It is likely that many steps in nuclea...…”

Functional Proteomic Analysis of Human Nucleolus

“…In the interchromatin space, various molecular species constantly associate and dissociate to give rise to transient nuclear domains that structurally support DNA and RNA metabolism (Phair and Misteli, 2000;Misteli, 2001). At present, numerous nuclear domains have been pointed out, although the composition and function of most of them are not yet fully elucidated (Matera, 1999).…”