The replication initiation determinant protein (RepID) modulates replication by recruiting CUL4 to chromatin

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Cell cycle progression relies on ubiquitin ligase complexes like CRL4 and SCF for DNA replication regulation.
• These complexes degrade chromatin substrates essential for controlling DNA synthesis.

Purpose of the Study:

• To elucidate the role of RepID (DCAF14/PHIP), a CRL4 complex member, in DNA replication.
• To investigate the functional relationship between RepID, CRL4, and the SCF complex involving SKP2 in cell cycle control.

Main Methods:

• Chromatin immunoprecipitation assays to identify protein-DNA interactions.
• Cellular sensitivity assays to SKP2 inhibitors upon RepID depletion.
• Analysis of genome re-replication events.

Main Results:

• RepID recruits the CRL4 complex to chromatin, playing a key role in chromosome licensing before DNA synthesis.
• Cells lacking RepID utilize the SKP2-containing SCF complex for cell cycle progression.
• RepID depletion enhances sensitivity to SKP2 inhibitors, leading to massive genome re-replication.
• RepID and SKP2 target distinct, non-overlapping sets of replication origins.

Conclusions:

• RepID is essential for CRL4-mediated DNA replication licensing.
• Distinct replication origin targeting by CRL components (RepID/CRL4 and SKP2/SCF) is crucial for executing the DNA replication program.
• This selective targeting ensures genomic stability by preventing re-initiation of DNA replication.