Description
- Abstract:
- The regulation of gene expression in eukaryotic cells is controlled by both chromatin dynamics and the actions of myriad components of the transcriptional machinery. While the roles of transcriptional machinery are fairly well understood, how they work in concert with different chromatin states to modulate gene expression is unclear. The histone code hypothesis suggests that histone modifications guide the inheritance of chromatin states to daughter cells as well as provide distinct sets of recognition motifs to recruit chromatin binding proteins to the gene locus. This recruitment of chromatin proteins would then result in stabilization or alteration of modifications and appropriately modulate gene transcription.<br/> One chromatin associated protein, Bromodomain-containing protein 2 (BRD2) is known to selectively bind acetylated histone H4. While previous work identified molecular interactions between BRD2 and transcriptional machinery, functions of BRD2 in mammalian embryogenesis remained unknown. In this work, we developed a mouse model deficient in BRD2 and found that the protein is required for the completion of embryogenesis. Embryos lacking BRD2 died soon after mid-gestation and displayed fully penetrant neurulation defects, resulting in hindbrain exencephaly. Additionally, we demonstrated that embryos lacking Brd2 expression display altered gene expression programs, including the mis-expression of multiple genes which guide neuronal development. Together these results implicate essential roles for BRD2 as a critical integrator of chromatin structure and transcription during mammalian embryogenesis and neurogenesis.<br/> As neural tube defects seen in BRD2-null embryos are strikingly similar to those seen in GCN5 mutant mice, we tested the hypothesis that these two proteins interact. We identified that in vivo BRD2 and GCN5 co-localize in developing neuroepithelium and also co-immunoprecipitate in mid-gestation whole embryo extracts. In mouse ES cell extracts, purification of GCN5-containing complexes revealed the co-association of BRD2. Finally, in cultured N2A cells, the C-terminal ET domain of BRD2 is shown to be dispensable for its association with GCN5 but important for its correct nuclear localization. Taken together, these results suggest that BRD2 may be acting to integrate the reading and the writing of chromatin modifications by guiding the histone acetyltransferase activity of GCN5.
- Notes:
- Thesis (Ph.D. -- Brown University (2013)
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Citation
Donovan, Diana J.,
"The Genetic and Biochemical Analysis of the Chromatin-Targeting Protein BRD2 in Mammalian Development"
(2013).
Molecular Biology, Cell Biology, and Biochemistry Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0NP22R9
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Molecular Biology, Cell Biology, and Biochemistry Theses and Dissertations
Theses and Dissertations for the Molecular Biology, Cell Biology, and Biochemistry department....