RAD50 regulates mitotic progression independent of DNA repair functions

Abstract

The Mre11A/RAD50/NBN complex (MRN) is an essential regulator of the cellular damage response after DNA double‐strand breaks (DSBs). More recent work has indicated that MRN may also impact on the duration of mitosis. We show here that RAD50‐deficient fibroblasts exhibit a marked delay in mitotic progression that can be rescued by lentiviral transduction of RAD50. The delay was observed throughout all mitotic phases in live cell imaging using GFP‐labeled H2B as a fluorescent marker. In complementation assays with RAD50 phosphorylation mutants, modifications at Ser635 had little effect on mitotic progression. By contrast with RAD50, fibroblast strains deficient in ATM or NBN did not show a significant slowing of mitotic progression. Ataxia‐telangiectasia‐like disorder (ATLD) fibroblasts with nuclease‐deficient MRE11A (p.W210C) tended to show slower mitosis, though by far not as significant as RAD50‐deficient cells. Inhibitor studies indicated that ATM kinase activity might not grossly impact on mitotic progression, while treatment with MRE11A inhibitor PFM39 modestly prolonged mitosis. Inhibition of ATR kinase significantly prolonged mitosis but this effect was mostly independent of RAD50 status. Taken together, our data unravel a mitotic role of RAD50 that can be separated from its known functions in DNA repair.

The deacetylation-phosphorylation regulation of SIRT2-SMC1A axis as a mechanism of antimitotic catastrophe in early tumorigenesis

“…Rad50, which is not found among the high-scoring interaction proteins, is a key component of the Mre11-Rad50-Nbs1 (MRN) complex involved in DNA double-strand break repair. Although RAD50 is reported to regulate mitotic progression independent of DNA repair functions, it is preferentially colocalized with chromosomes rather than centrosomes, spindle poles, or spindles, which more directly affect the assembly of cell division (54). Considering that SIRT2 is localized on the mitotic spindles and spindle pole from prophase until telophase, SIRT2 is colocalized with SMC1A but not RAD50 in mitosis.…”

Single-Cell Atlas of the Chinese Tongue Sole (Cynoglossus semilaevis) Ovary Reveals Transcriptional Programs of Oogenesis in Fish

“…Typical marker genes of oogenesis, such as gdf9 and dnd1 ( Liu and Ge, 2007 ; Yang et al, 2012 ), were widely expressed in the three identified germ cell types. Dazl ( Bachvarova et al, 2004 ; Li et al, 2016 ; Bertho et al, 2021 ) was highly expressed in early oogonia, while the mitotic marker rad50 ( Kostyrko et al, 2015 ; Völkening et al, 2020 ; Liu et al, 2021 ) was mainly expressed in mitotic oogonia ( Figure 1D ). In addition, we identified somatic cells based on the following markers: follicle cells ( foxl2 , amh and hsd17b1 ) ( Pisarska et al, 2011 ; Luo et al, 2020 ; Moolhuijsen and Visser, 2020 ; Li et al, 2021 ), endothelial cells ( fli1 and fn1a ) ( Nagai et al, 2018 ; Wu et al, 2021 ), T cells ( cd2 , cd247 and cd28 ) ( Hurley et al, 1994 ; Lundholm et al, 2010 ), macrophages ( cd68 , epx and mmp9 ) ( Hunyady et al, 1996 ; Sendler et al, 2018 ) and erythrocytes ( alas2 ) ( Munday et al, 2000 ; Tsang et al, 2017 ) ( Figure 1E ).…”

Mutation Spectra of the MRN (MRE11, RAD50, NBS1/NBN) Break Sensor in Cancer Cells

“…As the progression of cancer selects for advantageous mutations [133], disruption of some MRE11 conserved residues might not be beneficial. Supporting this, there is evidence that these three genes may also have independent functions [125,134]. Thus, some components of the MRN complex may be more critical for DSB repair than others.…”