RESUMO
The DNA polymerase zeta (Polζ) plays a critical role in bypassing DNA damage. REV3L, the catalytic subunit of Polζ, is also essential in mouse embryonic development and cell proliferation for reasons that remain incompletely understood. In this study, we reveal that REV3L protein interacts with heterochromatin components including repressive histone marks and localizes in pericentromeric regions through direct interaction with HP1 dimer. We demonstrate that Polζ/REV3L ensures progression of replication forks through difficult-to-replicate pericentromeric heterochromatin, thereby preventing spontaneous chromosome break formation. We also find that Rev3l-deficient cells are compromised in the repair of heterochromatin-associated double-stranded breaks, eliciting deletions in late-replicating regions. Lack of REV3L leads to further consequences that may be ascribed to heterochromatin replication and repair-associated functions of Polζ, with a disruption of the temporal replication program at specific loci. This is correlated with changes in epigenetic landscape and transcriptional control of developmentally regulated genes. These results reveal a new function of Polζ in preventing chromosome instability during replication of heterochromatic regions.
Assuntos
Replicação do DNA , Proteínas de Ligação a DNA/genética , DNA Polimerase Dirigida por DNA/genética , DNA/genética , Células-Tronco Embrionárias/metabolismo , Epigênese Genética , Heterocromatina/metabolismo , Animais , Linhagem Celular , Linhagem Celular Transformada , Proliferação de Células , Homólogo 5 da Proteína Cromobox/genética , Homólogo 5 da Proteína Cromobox/metabolismo , Instabilidade Cromossômica , DNA/metabolismo , Quebras de DNA de Cadeia Dupla , Proteínas de Ligação a DNA/metabolismo , DNA Polimerase Dirigida por DNA/metabolismo , Embrião de Mamíferos , Células-Tronco Embrionárias/citologia , Fibroblastos/citologia , Fibroblastos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Células HeLa , Heterocromatina/química , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Células NIH 3T3 , Transdução de SinaisRESUMO
Passive cavitation detection can be performed to monitor microbubble activity during brain therapy. Microbubbles under ultrasound exposure generate a response characterized by multiple nonlinear emissions. Here, the wide bandwidth of capacitive micromachined ultrasonic transducers (CMUTs) was exploited to monitor the microbubble signature through a rat skull and a macaque skull. The intrinsic nonlinearity of the CMUTs was characterized in receive mode. Indeed, undesirable nonlinear components generated by the CMUTs must be minimized as they can mask the microbubble harmonic response. The microbubble signature at harmonic and ultra-harmonic components (0.5-6 MHz) was successfully extracted through a rat skull using moderate bias voltage.
