| Abstract: |
We used micrococcal nuclease to separate murine erythroleukemia cell (MELC) chromatin into soluble and insoluble fractions which differ in gene content and chromatin structure. Genes that are not expressed in the erythroid lineage, such as the Igα and albumin genes. distribute preferentially into the soluble rather than the insoluble fraction, and are organized into nucleosomes in both fractions. Both α1- and βmaj-globin genes are enriched in the insoluble fraction and are organized into structures that are partially devoid of nucleosomes in uninduced MELC, when the genes are transcriptionally inactive. Following chemical induction of MELC and the onset of globin gene transcription, globin gene enrichment and nucleosome disruption in the insoluble chromatin fraction increase. Using seven DNA subclones that span the βmaj-globin gene we show that insolubility and nucleosome disruption are largely limited to DNA sequences lying within the transcribed domain. Non-transcribed, flanking sequences are soluble and organized into nucleosomes. In addition, the globin genes found in insoluble, non-nucleosomal chromatin contain previously engaged RNA polymerases which can elongate globin RNA chains in vitro in a pattern qualitatively and quantitatively similar to intact nuclei. These results are discussed in terms of a model for globin gene activation during erythropoeisis. © 1985. |
| Keywords: |
nonhuman; animal cell; mouse; animal; mice; heredity; genes; cell line; genetic transcription; transcription, genetic; in vitro study; rna; gene activation; genetic engineering; chromatin; globin gene; models, genetic; radioisotope; nucleic acid hybridization; electrophoresis, polyacrylamide gel; globins; nucleosome; nucleosomes; leukemia, erythroblastic, acute; micrococcal nuclease; priority journal; support, non-u.s. gov't; support, u.s. gov't, p.h.s.; erythroleukemia cell; blood and hemopoietic system
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