RESUMEN
The centromere, a chromosome locus defined by the histone H3-like protein centromeric protein A (CENP-A), promotes assembly of the kinetochore to bind microtubules during cell division. Centromere maintenance requires CENP-A to be actively replenished by dedicated protein machinery in the early G1 phase of the cell cycle to compensate for its dilution after DNA replication. Cyclin-dependent kinases (CDKs) limit CENP-A deposition to once per cell cycle and function as negative regulators outside of early G1. Antithetically, Polo-like kinase 1 (PLK1) promotes CENP-A deposition in early G1, but the molecular details of this process are still unknown. We reveal here a phosphorylation network that recruits PLK1 to the deposition machinery to control a conformational switch required for licensing the CENP-A deposition reaction. Our findings clarify how PLK1 contributes to the epigenetic maintenance of centromeres.
Asunto(s)
Proteínas de Ciclo Celular , Proteína A Centromérica , Centrómero , Proteínas Cromosómicas no Histona , Epigénesis Genética , Quinasa Tipo Polo 1 , Humanos , Proteínas de Ciclo Celular/metabolismo , Centrómero/metabolismo , Proteína A Centromérica/metabolismo , Proteínas Cromosómicas no Histona/metabolismo , Fase G1 , Células HeLa , Cinetocoros/metabolismo , Fosforilación , Quinasa Tipo Polo 1/genética , Quinasa Tipo Polo 1/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas/genéticaRESUMEN
Chromosome instability (CIN) contributes to resistance to therapies and tumor evolution. Although natural killer (NK) cells can eliminate cells with complex karyotypes, high-CIN human tumors have an immunosuppressive phenotype. To understand which CIN-associated molecular features alter immune recognition during tumor evolution, we overexpress Polo-like kinase 1 (Plk1) in a Her2+ breast cancer model. These high-CIN tumors activate a senescence-associated secretory phenotype (SASP), upregulate PD-L1 and CD206, and induce non-cell-autonomous nuclear factor κB (NF-κß) signaling, facilitating immune evasion. Single-cell RNA sequencing from pre-neoplastic mammary glands unveiled the presence of Arg1+ macrophages, NK cells with reduced effector functions, and increased resting regulatory T cell infiltration. We further show that high PLK1-expressing human breast tumors display gene expression patterns associated with SASP, NF-κß signaling, and immune suppression. These findings underscore the need to understand the immune landscape in CIN tumors to identify more effective therapies, potentially combining immune checkpoint or NF-κß inhibitors with current treatments.
