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U2 and U1 snRNA gene loci associate with coiled bodies
Author(s) -
Smith Kelly P.,
Carter Kenneth C.,
Johnson Carol V.,
Lawrence Jeanne Bentley
Publication year - 1995
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240590408
Subject(s) - locus (genetics) , gene , biology , small nuclear rna , genetics , microbiology and biotechnology , gene expression , non coding rna
The coiled bodies are nuclear structures rich in a variety of nuclear and nucleolar components including snRNAs. We have investigated the possibility that coiled bodies may associate with snRNA genes and report here that there is a high degree of association between U2 and U1 genes with a subset of coiled bodies. As investigated in human HeLa cells grown in monolayer culture, about 75% of the nuclei had at least one U2 gene associated with a coiled body, and 45% had at least one U1 locus associated. In another suspension‐grown HeLa cell strain, 92% of cells showed association of one or more U2 genes with coiled bodies. In contrast to the U2 and U1 gene associations, a locus closely linked to the U2 gene cluster appeared associated with a coiled body only in 10% of cells. Associated snRNA gene signals were repeatedly positioned at the edge of the coiled body. Thus, this association was highly nonrandom and spatically precise. Our analysis revealed a much higher frequency of association for closely spaced “doublet” U2 gene signals, with over 80% of paired signals associated as opposed to 35% for single U2 signals. This finding, coupled with the fact that not all genes were associated in all cells, suggested the possibility of a cell‐cycle‐dependent, possibly S‐phase, association. However, an analysis of S‐ and non‐S‐phase cells using BrdU incorporation or cell synchronization did not indicate an increased level of association in S‐phase. These and other results suggested that a substantial fraction of paired U2 signals represented association of U2 genes on homologous chromosomes rather than only replicated DNA. Furthermore, triple lable analysis showed that in a significant fraction of cells U1 and U2 genes were both associated with the same coiled body. U1 and U2 genes were closely paired in approximately 20% of cells, over 60% of which were associated with a readily identifiable coiled body. This finding raises the possibility that multiple genes of a particular class may be in association with each coiled body. Thus, the coiled body may be a dynamic structure which transiently interacts with or is formed by one or more specific genetic loci, possibly carrying out some function related to their expression. © 1995 Wiley‐Liss, Inc.