Molecular chaperone Hsp90 regulates REV1-mediated mutagenesis

Area of Science:

• Molecular Biology
• DNA Repair Mechanisms
• Cancer Biology

Background:

• REV1 is a Y-family polymerase crucial for mutagenic translesion DNA synthesis (TLS), implicated in tumor development.
• Monoubiquitinated proliferating cell nuclear antigen (PCNA) is thought to recruit REV1 to DNA damage sites.
• Regulation of REV1 in higher eukaryotes remains largely unknown, despite evidence in yeast.

Purpose of the Study:

• To investigate the regulatory mechanisms of REV1 in human cells.
• To determine the role of the molecular chaperone Hsp90 in REV1 regulation.
• To elucidate the impact of Hsp90 on TLS-mediated mutagenesis.

Main Methods:

• In vivo and in vitro binding assays to assess Hsp90-REV1 interaction.
• Hsp90 inhibition studies using specific inhibitors.
• Analysis of REV1 protein levels and proteasomal degradation.
• Assessment of UV-induced mutagenesis and focus formation.
• Investigation of the interaction between REV1 and monoubiquitinated PCNA.

Main Results:

• Hsp90 specifically binds to REV1 in human cells.
• Hsp90 inhibition leads to decreased REV1 protein levels via proteasomal degradation.
• Hsp90 inhibition suppresses UV-induced mutagenesis.
• Hsp90 inhibition disrupts the REV1-monoubiquitinated PCNA interaction.
• Hsp90 inhibition suppresses UV-induced focus formation of REV1.

Conclusions:

• Hsp90 is a critical regulator of REV1 stability and function in human cells.
• Hsp90 facilitates the interaction between REV1 and monoubiquitinated PCNA, essential for TLS.
• Hsp90 plays a novel role in regulating TLS-mediated mutagenesis through REV1 stabilization.