Polycomb RING1A- and RING1B-dependent histone H2A monoubiquitylation at pericentromeric regions promotes S-phase progression.
The functions of polycomb products extend beyond their well-known activity as transcriptional regulators to include genome duplication processes. Polycomb activities during DNA replication and DNA damage repair are unclear, particularly without induced replicative stress. We have used a cellular model of conditionally inactive polycomb E3 ligases (RING1A and RING1B), which monoubiquitylate lysine 119 of histone H2A (H2AK119Ub), to examine DNA replication in unperturbed cells. We identify slow elongation and fork stalling during DNA replication that is associated with the accumulation of mid and late S-phase cells. Signs of replicative stress and colocalisation of double-strand breaks with chromocenters, the sites of coalesced pericentromeric heterocromatic (PCH) domains, were enriched in cells at mid S-phase, the stage at which PCH is replicated. Altered replication was rescued by targeted monoubiquitylation of PCH through methyl-CpG binding domain protein 1. The acute senescence associated with the depletion of RING1 proteins, which is mediated by p21 (also known as CDKN1A) upregulation, could be uncoupled from a response to DNA damage. These findings link cell proliferation and the polycomb proteins RING1A and RING1B to S-phase progression through a specific function in PCH replication.
Biología Celular y Molecular, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid 28040, Spain.
Mónica
M
Bravo
Biología Celular y Molecular, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid 28040, Spain.
Fabio
F
Nicolini
Biología Celular y Molecular, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid 28040, Spain.
Katarzyna
K
Starowicz
Inestabilidad Genómica, Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla, Sevilla 41092, Spain.
Sonia
S
Barroso
Biología del Cáncer, Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid 28029, Spain.
Carmela
C
Calés
Inestabilidad Genómica, Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla, Sevilla 41092, Spain.
Andrés
A
Aguilera
Biología Celular y Molecular, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid 28040, Spain mvidal@cib.csic.es.
Miguel
M
Vidal
D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D002503:Centromere / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D051379:Mice; D063150:Polycomb Repressive Complex 1 / Q000235:genetics / Q000378:metabolism*; D016196:S Phase / Q000502:physiology; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
D006657:Histones; D063150:Polycomb Repressive Complex 1; C489840:Ring1 protein, mouse; C489842:Rnf2 protein, mouse; D044767:Ubiquitin-Protein Ligases
Pericentric heterochromatin; Polycomb; RING1A; RING1B; Replication