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A unique role for enhancers is revealed during early mouse development
Author(s) -
Majumder Sadhan,
Depamphilis Melvin L.
Publication year - 1995
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/bies.950171010
Subject(s) - enhancer , biology , pronucleus , tata box , enhancer rnas , transcription factor , chromatin , genetics , microbiology and biotechnology , transcription (linguistics) , psychological repression , coactivator , gene , promoter , gene expression , zygote , embryogenesis , linguistics , philosophy
Transcription and replication of genes in mammalian cells always requires a promoter or replication origin, respectively, but the ability of enhancers to stimulate these regulatory elements and the interactions that mediate this stimulation are developmentally acquired. The primary function of enhancers is to prevent repression, which appears to result from particular components of chromatin structure. Factors responsible for this repression are present in the maternal nucleus of oocytes and its descendant, the maternal pronucleus of mouse 1‐cell embryos and in mouse 2‐cell embryos, but are absent in the paternal pronucleus. Thus, enhancers are not needed to achieve efficient transcription and replication in paternal pronuclei. However, enhancers, even in the presence of their specific activation protein, are inactive prior to formation of a 2‐cell embryo, suggesting that a coactivator essential for enhancer function is not available until zygotic gene expression begins. Furthermore, enhancer stimulation of transcription appears to be mediated through a promoter transcription factor, but this interaction can change as cells undergo differentiation, switching from a TATA‐box independent to a TATA‐box dependent mode.