Gene-repressing epigenetic reader EED unexpectedly enhances cyclinD1 gene activation

• Published in: Molecular therapy. Nucleic acids 2023-03, Vol.31, p.717-729
• Main Authors: Zhang, Mengxue, Li, Jing, Wang, Qingwei, Urabe, Go, Tang, Runze, Huang, Yitao, Mosquera, Jose Verdezoto, Kent, K. Craig, Wang, Bowen, Miller, Clint L., Guo, Lian-Wang
• Format: Article
• Language: English
• Subjects: BRD4 in p57 repression; cooperativity between EED and BRD4; EED in Ccnd1 activation; epigenetic readers; MT: Oligonucleotides: Therapies and Applications; neointima; Original; smooth muscle cell proliferation
• ISSN: 2162-2531; 2162-2531
• DOI: 10.1016/j.omtn.2023.02.024

Epigenetically switched, proliferative vascular smooth muscle cells (SMCs) form neointima, engendering stenotic diseases. Histone-3 lysine-27 trimethylation (H3K27me3) and acetylation (H3K27ac) marks are associated with gene repression and activation, respectively. The polycomb protein embryonic ectoderm development (EED) reads H3K27me3 and also enhances its deposition, hence is a canonical gene repressor. However, herein we found an unexpected role for EED in activating the bona fide pro-proliferative gene Ccnd1 (cyclinD1). EED overexpression in SMCs increased Ccnd1 mRNA, seemingly contradicting its gene-repressing function. However, consistently, EED co-immunoprecipitated with gene-activating H3K27ac reader BRD4, and they co-occupied at both mitogen-activated Ccnd1 and mitogen-repressed P57 (bona fide anti-proliferative gene), as indicated by chromatin immunoprecipitation qPCR. These results were abolished by an inhibitor of either the EED/H3K27me3 or BRD4/H3K27ac reader function. In accordance, elevating BRD4 increased H3K27me3. In vivo, while EED was upregulated in rat and human neointimal lesions, selective EED inhibition abated angioplasty-induced neointima and reduced cyclinD1 in rat carotid arteries. Thus, results uncover a previously unknown role for EED in Ccnd1 activation, likely via its cooperativity with BRD4 that enhances each other’s reader function; i.e., activating pro-proliferative Ccnd1 while repressing anti-proliferative P57. As such, this study confers mechanistic implications for the epigenetic intervention of neointimal pathology. [Display omitted] Guo and colleagues report a surprising finding that two histone-code readers, EED and BRD4 which are commonly known for their opposing roles in gene regulation, interact and cooperate to enhance each other’s function.