High affinity binding of H3K14ac through collaboration of bromodomains 2, 4 and 5 is critical for the molecular and tumor suppressor functions of PBRM1.

Authors

Lili Liao, Thomas Jefferson University; Yale UniversityFollow
Nilda L. Alicea-Velázquez, State University of New York Upstate Medical University; Central Connecticut State University
Lauren Langbein, Thomas Jefferson UniversityFollow
Xiaohua Niu, The Sixth Affiliated Hospital of Guangzhou Medical University
Weijia Cai, Thomas Jefferson UniversityFollow
Eun-Ah Cho, Thomas Jefferson University; Fox Chase Cancer CenterFollow
Meiling Zhang, Yale University
Celeste B. Greer, Vanderbilt University
Qin Yan, Yale University
Michael S. Cosgrove, State University of New York Upstate Medical University
Haifeng Yang, Thomas Jefferson UniversityFollow

Document Type

Article

Publication Date

12-26-2018

Comments

This article has been peer reviewed. It is the author’s final published version in Molecular Oncology, December 2018.

The published version is available at https://doi.org/10.1002/1878-0261.12434. Copyright © Liao et al.

Abstract

Polybromo-1 (PBRM1) is an important tumor suppressor in kidney cancer. It contains six tandem bromodomains (BDs), which are specialized structures that recognize acetyl-lysine residues. While BD2 has been found to bind acetylated histone H3 lysine 14 (H3K14ac), it is not known whether other BDs collaborate with BD2 to generate strong binding to H3K14ac, and the importance of H3K14ac recognition for the molecular and tumor suppressor function of PBRM1 is also unknown. We discovered that full-length PBRM1, but not its individual BDs, strongly binds H3K14ac. BDs 2, 4, and 5 were found to collaborate to facilitate strong binding to H3K14ac. Quantitative measurement of the interactions between purified BD proteins and H3K14ac or nonacetylated peptides confirmed the tight and specific association of the former. Interestingly, while the structural integrity of BD4 was found to be required for H3K14ac recognition, the conserved acetyl-lysine binding site of BD4 was not. Furthermore, simultaneous point mutations in BDs 2, 4, and 5 prevented recognition of H3K14ac, altered promoter binding and gene expression, and caused PBRM1 to relocalize to the cytoplasm. In contrast, tumor-derived point mutations in BD2 alone lowered PBRM1's affinity to H3K14ac and also disrupted promoter binding and gene expression without altering cellular localization. Finally, overexpression of PBRM1 variants containing point mutations in BDs 2, 4, and 5 or BD2 alone failed to suppress tumor growth in a xenograft model. Taken together, our study demonstrates that BDs 2, 4, and 5 of PBRM1 collaborate to generate high affinity to H3K14ac and tether PBRM1 to chromatin. Mutations in BD2 alone weaken these interactions, and this is sufficient to abolish its molecular and tumor suppressor functions.

Recommended Citation

Liao, Lili; Alicea-Velázquez, Nilda L.; Langbein, Lauren; Niu, Xiaohua; Cai, Weijia; Cho, Eun-Ah; Zhang, Meiling; Greer, Celeste B.; Yan, Qin; Cosgrove, Michael S.; and Yang, Haifeng, "High affinity binding of H3K14ac through collaboration of bromodomains 2, 4 and 5 is critical for the molecular and tumor suppressor functions of PBRM1." (2018). Department of Pathology, Anatomy, and Cell Biology Faculty Papers. Paper 267.
https://jdc.jefferson.edu/pacbfp/267

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 License.

PubMed ID

30585695

Language

English