Mre11 is essential for the maintenance of chromosomal DNA in vertebrate cells

Yeast Mre11 functions with Rad50 and Xrs2 in a complex that has pivotal rol es in homologous recombination (HR) and non-homologous end-joining (NHEJ) D NA double-strand break (DSB) repair pathways. Vertebrate Mre11 is essential . Conditionally, MRE11 null chicken DT40 cells accumulate chromosome breaks and die upon Mre11 repression, showing frequent centrosome amplification. Mre11 deficiency also causes increased radiosensitivity and strongly reduce d targeted integration frequencies. Mre11 is, therefore, crucial for HR and essential in mitosis through its role in chromosome maintenance by recombi national repair Surprisingly perhaps, given the role of Mre11 in yeast NHEJ , disruption of NHEJ by deletion of KU70 greatly exacerbates the effects of MRE11 deficiency, revealing a significant Mre11-independent component of m etazoan NHEJ.