The Rad50 hook domain regulates DNA damage signaling and tumorigenesis

Abstract

The Mre11 complex (Mre11, Rad50, and Nbs1) is a central component of the DNA damage response (DDR), governing both double-strand break repair and DDR signaling. Rad50 contains a highly conserved Zn 2+ -dependent homodimerization interface, the Rad50 hook domain. Mutations that inactivate the hook domain produce a null phenotype. In this study, we analyzed mutants with reduced hook domain function in an effort to stratify hookdependent Mre11 complex functions. One of these alleles, Rad50 46 , conferred reduced Zn 2+ affinity and dimerization efficiency. Homozygous Rad50 46/46 mutations were lethal in mice. However, in the presence of wildtype Rad50, Rad50 46 exerted a dominant gain-of-function phenotype associated with chronic DDR signaling. At the organismal level, Rad50 +/46 exhibited hydrocephalus, liver tumorigenesis, and defects in primitive hematopoietic and gametogenic cells. These outcomes were dependent on ATM, as all phenotypes were mitigated in Rad50 +/46 Atm +/-mice. These data reveal that the murine Rad50 hook domain strongly influences Mre11 complex-dependent DDR signaling, tissue homeostasis, and tumorigenesis.

The MRE11–RAD50–NBS1 Complex Conducts the Orchestration of Damage Signaling and Outcomes to Stress in DNA Replication and Repair

“…The Zn-hook and coiled-coil domain are critical for functional RAD50 DNA tethering and ATM activation (54–56). Yet, two Rad50 subunits are also held flexibly by the Mre11 dimer, whose subunits form a flexibly linked helix-bundle interface at the base of two Rad50 subunits that allow the Rad50 dimer to open upon ATP hydrolysis and to expose the Mre11 DNA-binding channel for nuclease excision.…”

Structural mechanism of ATP‐dependent DNA binding and DNA end bridging by eukaryotic Rad50

“…Rad50 further possesses a 15-50-nm-long coiled-coil domain with a terminal Znhook dimerization motif (Hopfner et al, 2002;Schiller et al, 2014). The precise mechanistic functions of the coiled-coil domains are still unclear, but they play an important role in NHEJ, ATM activation, and DNA end processing (Hohl et al, 2011;Lee et al, 2013;Roset et al, 2014).…”

The MRE11 complex: An important source of stress relief

“…This domain is crucial for the function and stability of the MRE11 complex and it is thought to primarily act as an interface that facilitates the formation of MRE11 complex multimers. Complete loss of hook function leads to a null phenotype but milder mutations have been identified and were recently generated in mice [18,87,88]. While mice carrying homozygous mutations in the RAD50 hook were inviable, cells and tissues heterozygous for mutant RAD50 hook alleles exhibited increased ATM signaling in the absence of exogenous damage.…”