Measuring Genome-Wide Nascent Nucleosome Assembly Using ReIN-Map.

Area of Science:

• Molecular Biology
• Epigenetics
• Genomics

Background:

• Nucleosome assembly after DNA replication is vital for transmitting epigenetic information and maintaining genome integrity.
• This process, known as replication-coupled (RC) nucleosome assembly, necessitates tight coordination between DNA replication and nucleosome formation.
• Understanding RC nucleosome assembly is key to comprehending inheritance of epigenetic marks and overall genome stability.

Purpose of the Study:

• To introduce a novel genome-wide method, Replication-Intermediate Nucleosome Mapping (ReIN-Map), for assessing RC nucleosome assembly in vivo.
• To provide a tool for monitoring nucleosome occupancy on newly synthesized DNA strands.
• To enable detailed analysis of the dynamics of nucleosome assembly during DNA replication.

Main Methods:

• ReIN-Map utilizes next-generation sequencing and in vivo labeling of newly synthesized DNA with 5-bromo-2'-deoxyuridine (BrdU).
• The method involves parallel analyses: micrococcal nuclease digestion (MNase-seq) for nucleosome formation and sonication shearing (Sonication-seq) for newly synthesized DNA.
• Chromatin containing newly replicated DNA is enriched via BrdU immunoprecipitation (BrdU-IP) followed by strand-specific sequencing.

Main Results:

• The study presents ReIN-Map as a viable method for genome-wide analysis of RC nucleosome assembly.
• The methodology allows for precise measurement of nucleosome occupancy on nascent DNA strands.
• This enables a detailed, in vivo snapshot of nucleosome assembly dynamics during replication.

Conclusions:

• ReIN-Map offers a powerful approach to study the fundamental process of RC nucleosome assembly.
• This method facilitates a deeper understanding of epigenetic information inheritance and genome integrity maintenance.
• The developed technique provides new avenues for investigating the coordination between DNA replication and chromatin organization.