Macromolecular Synthesis and Degradation during Terminal Erythroid Cell Development

Bonanou‐Tzedaki, Sophia A.; Arnstein, H. R. V.

doi:10.1007/978-1-4757-9528-8_5

Cited by 2 publications

(1 citation statement)

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“…During terminal erythroid differentiation, the nucleus is progressively condensed and eventually becomes transcriptionally inactive. The globin loci, which are transcribed during the terminal phase of erythroid differentiation when heterochromatinization is occurring, are adapted to remain active in this context (2). However, most sites into which a transgene may randomly integrate will be inactivated during terminal differentiation.…”

Section: Discussionmentioning

confidence: 99%

A Globin Enhancer Acts by Increasing the Proportion of Erythrocytes Expressing a Linked Transgene

Sutherland

Martin

Whitelaw

1997

Molecular and Cellular Biology

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Enhancer elements have been shown to affect the probability of a gene establishing an active transcriptional state and suppress the silencing of reporter genes in cell lines, but their effect in transgenic mice has been obscured by the use of assays that do not assess expression on a cell-by-cell basis. We have examined the effect of a globin enhancer on the variegation of lacZ expression in erythrocytes of transgenic mice. Mice carrying lacZ driven by the ␣-globin promoter exhibit ␤-galactosidase (␤-Gal) expression in only a very small proportion of embryonic erythrocytes. When the transgenic construct also contains the ␣HS-40 enhancer, which controls expression of the ␣-globin gene, expression is seen in a high proportion of embryonic erythrocytes, although there are variations between transgenic lines which can be attributed to different sites of integration. Analysis of ␤-Gal expression levels suggests that expressing cells in lines carrying only the ␣-globin promoter express as much ␤-Gal as those in which the transgene also contains ␣HS-40. A marked decline in transgene expression occurs as mice age, which is mainly due to a decrease in the proportion of cells expressing the transgene. Thus, a globin enhancer can act to suppress variegation of a linked transgene; this result is consistent with a model in which enhancers act to establish and maintain an active domain without directly affecting the transcriptional rate.

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Section: Discussionmentioning

confidence: 99%