RESUMO
Histone H3 lysine 9 methylation (H3K9me) is essential for cellular homeostasis; however, its contribution to development is not well established. Here, we demonstrate that the H3K9me2 demethylase PHF2 is essential for neural progenitor proliferation in vitro and for early neurogenesis in the chicken spinal cord. Using genome-wide analyses and biochemical assays we show that PHF2 controls the expression of critical cell cycle progression genes, particularly those related to DNA replication, by keeping low levels of H3K9me3 at promoters. Accordingly, PHF2 depletion induces R-loop accumulation that leads to extensive DNA damage and cell cycle arrest. These data reveal a role of PHF2 as a guarantor of genome stability that allows proper expansion of neural progenitors during development.
Assuntos
Dano ao DNA , Histona Desmetilases/metabolismo , Proteínas de Homeodomínio/metabolismo , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismo , Animais , Diferenciação Celular/fisiologia , Proliferação de Células/fisiologia , Embrião de Galinha , Metilação de DNA , Células-Tronco Embrionárias , Epigênese Genética , Estudo de Associação Genômica Ampla , Histona Desmetilases/genética , Histonas/metabolismo , Proteínas de Homeodomínio/genética , Camundongos , Camundongos Endogâmicos C57BL , Células-Tronco Neurais/enzimologia , Neurogênese/fisiologia , Regiões Promotoras Genéticas , Fatores de Transcrição/metabolismoRESUMO
The minichromosome maintenance (MCM) helicase physically interacts with the recombination proteins Rad51 and Rad52 from yeast to human cells. We show, in Saccharomyces cerevisiae, that these interactions occur within a nuclease-insoluble scaffold enriched in replication/repair factors. Rad51 accumulates in a MCM- and DNA-binding-independent manner and interacts with MCM helicases located outside of the replication origins and forks. MCM, Rad51, and Rad52 accumulate in this scaffold in G1 and are released during the S phase. In the presence of replication-blocking lesions, Cdc7 prevents their release from the scaffold, thus maintaining the interactions. We identify a rad51 mutant that is impaired in its ability to bind to MCM but not to the scaffold. This mutant is proficient in recombination but partially defective in single-stranded DNA (ssDNA) gap filling and replication fork progression through damaged DNA. Therefore, cells accumulate MCM/Rad51/Rad52 complexes at specific nuclear scaffolds in G1 to assist stressed forks through non-recombinogenic functions.