COILED BODIES CONTAIN U7 SMALL NUCLEAR-RNA AND ASSOCIATE WITH SPECIFIC DNA-SEQUENCES IN INTERPHASE HUMAN-CELLS

Coiled bodies (CBs) are nuclear organelles whose structures appear to be highly conserved in evolution. In rapidly cycling cells, they are t ypically located in the nucleoplasm but are often found in contact wit h the nucleolus. The CBs in human cells contain a unique protein, call ed p80-coilin. Studies on amphibian oocyte nuclei have revealed a prot ein within the ''sphere'' organelle that shares significant structural similarity to p80-coilin. Spheres and CBs are also highly enriched in small nuclear ribonucleoproteins and other RNA-processing components. We present evidence that, like spheres, CBs contain U7 small nuclear RNA (snRNA) and associate with specific chromosomal loci. Using biotin ylated 2'-O-methyl oligonucleotides complementary to the 5' end of U7 snRNA and fluorescence in situ hybridization, we show that U7 is distr ibuted throughout the nucleoplasm, excluding nucleoli, and is concentr ated in CBs. Interestingly, we found that CBs often associate with sub sets of the histone, U1, and U2 snRNA gene loci in interphase HeLa-ATC C and HEp-2 monolayer cells. However, in a strain of suspension-grown HeLa cells, called HeLa-JS1000, we found a much lower rate of associat ion between CBs and snRNA genes. Possible roles for CBs in the metabol ism of these various histone and snRNAs are discussed.