Author: ["Anaïck Lagana","Jonas F. Dorn","Valérie De Rop","Anne-Marie Ladouceur","Amy S. Maddox","Paul S. Maddox"]
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Abstract
The histone H3 variant CENP-A defines centromeric chromatin, but it is not known how it is maintained at these loci. The CENP-A licensing factor HsKNL2, the small GTPases Cdc42 and Rac, and their regulators Ect2 and MgcRacGAP, coordinately promote the stability of newly loaded CENP-A at centromeres. Epigenetic mechanisms regulate genome activation in diverse events, including normal development and cancerous transformation. Centromeres are epigenetically designated chromosomal regions that maintain genomic stability by directing chromosome segregation during cell division. The histone H3 variant CENP-A resides specifically at centromeres, is fundamental to centromere function and is thought to act as the epigenetic mark defining centromere loci. Mechanisms directing assembly of CENP-A nucleosomes have recently emerged, but how CENP-A is maintained after assembly is unknown. Here, we show that a small GTPase switch functions to maintain newly assembled CENP-A nucleosomes. Using functional proteomics, we found that MgcRacGAP (a Rho family GTPase activating protein) interacts with the CENP-A licensing factor HsKNL2. High-resolution live-cell imaging assays, designed in this study, demonstrated that MgcRacGAP, the Rho family guanine nucleotide exchange factor (GEF) Ect2, and the small GTPases Cdc42 and Rac, are required for stability of newly incorporated CENP-A at centromeres. Thus, a small GTPase switch ensures epigenetic centromere maintenance after loading of new CENP-A.Cite this article
Lagana, A., Dorn, J., De Rop, V. et al. A small GTPase molecular switch regulates epigenetic centromere maintenance by stabilizing newly incorporated CENP-A. Nat Cell Biol 12, 1186–1193 (2010). https://doi.org/10.1038/ncb2129 