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Fanconi anemia signaling and Mus81 cooperate to safeguard development and crosslink repair.

Larin M, Gallo D, Tamblyn L, Yang J, Liao H, Sabat N, Brown GW, McPherson JP - Nucleic Acids Res. (2014)

Bottom Line: Individuals with Fanconi anemia (FA) are susceptible to bone marrow failure, congenital abnormalities, cancer predisposition and exhibit defective DNA crosslink repair.This cooperativity of FancC and Mus81 in developmental outcome was also mirrored in response to crosslink damage and chromosomal integrity.Thus, our findings reveal that both pathways safeguard against DNA damage from exceeding a critical threshold that triggers proliferation arrest and apoptosis, leading to compromised in utero development.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Toxicology, University of Toronto, Toronto, M5S 1A8, Canada.

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Genomic instability in FkoMko immortalized cells treated with DNA damaging agents. (a) Representative chromosomal aberrations scored (arrows). (b) Untreated immortalized fibroblasts: total aberrations, fragments and double minutes. Data represent the mean incidence per metaphase ±SD. **P < 0.005 for FkoMhet or FkoMko versus FhetMhet or FhetMko, †P < 0.05 for FkoMko or FkoMhet versus FhetMko or FhetMhet. (c) Immortalized fibroblasts exposed to mitomycin-C: total aberrations, fragments, breaks, radials and pulverized chromosomes. ***P < 0.001 for FkoMko or FkoMhet versus FhetMhet and FhetMko, †P < 0.05 for FkoMko versus FhetMhet or FhetMko, ±P < 0.05 for FkoMko versus FhetMhet, ††P < 0.01 for FkoMko versus FhetMhet or FhetMko. (d) Immortalized fibroblasts exposed to Ara-C: total aberrations, fragments and double minutes. *P < 0.05 for FkoMko versus FhetMhet, †P < 0.05 for FkoMhet or FkoMko versus FhetMhet or FhetMko, +P < 0.05 for FkoMhet versus FhetMko, ††P < 0.005 for FkoMko versus FhetMko and FhetMhet. All data analyzed by one-way ANOVA followed by Holm–Sidak post hoc.
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Figure 7: Genomic instability in FkoMko immortalized cells treated with DNA damaging agents. (a) Representative chromosomal aberrations scored (arrows). (b) Untreated immortalized fibroblasts: total aberrations, fragments and double minutes. Data represent the mean incidence per metaphase ±SD. **P < 0.005 for FkoMhet or FkoMko versus FhetMhet or FhetMko, †P < 0.05 for FkoMko or FkoMhet versus FhetMko or FhetMhet. (c) Immortalized fibroblasts exposed to mitomycin-C: total aberrations, fragments, breaks, radials and pulverized chromosomes. ***P < 0.001 for FkoMko or FkoMhet versus FhetMhet and FhetMko, †P < 0.05 for FkoMko versus FhetMhet or FhetMko, ±P < 0.05 for FkoMko versus FhetMhet, ††P < 0.01 for FkoMko versus FhetMhet or FhetMko. (d) Immortalized fibroblasts exposed to Ara-C: total aberrations, fragments and double minutes. *P < 0.05 for FkoMko versus FhetMhet, †P < 0.05 for FkoMhet or FkoMko versus FhetMhet or FhetMko, +P < 0.05 for FkoMhet versus FhetMko, ††P < 0.005 for FkoMko versus FhetMko and FhetMhet. All data analyzed by one-way ANOVA followed by Holm–Sidak post hoc.

Mentions: To determine whether the heightened repair defect in FkoMko cells reflects distinct contributions by FancC and Mus81 in the repair of specific lesions, we analyzed metaphase chromosomes from immortalized fibroblasts that were either untreated or exposed to either mitomycin-C or Ara-C (Figure 7). FkoMko-immortalized cells demonstrated a significantly higher number of chromosomal aberrations per metaphase than either FhetMhet (P < 0.001) or FhetMko (P = 0.001) cells, however they did not differ significantly from FkoMhet cells with regard to total aberrations. FkoMhet-immortalized fibroblasts demonstrated a significantly higher number of aberrations per metaphase than FhetMhet or FhetMko cells (P = 0.003; Figure 7B). Interestingly, pulverized chromosomes were not detected in untreated immortalized fibroblasts. Instead, significant changes in the incidence of aberrations were restricted to fragments and another distinct aberration appearing as paired chromosomal fragments or ‘double minutes’. The incidence of fragments was higher in both FkoMko and FkoMhet cells (P = 0.03 versus FhetMko and P = 0.02 versus FhetMhet), similarly incidence of double minutes was higher in FkoMko (P < 0.001 versus FhetMko and P = 0.001 versus FhetMhet) and FkoMhet cells (P = 0.009 versus FhetMko and P = 0.01 versus FhetMhet).


Fanconi anemia signaling and Mus81 cooperate to safeguard development and crosslink repair.

Larin M, Gallo D, Tamblyn L, Yang J, Liao H, Sabat N, Brown GW, McPherson JP - Nucleic Acids Res. (2014)

Genomic instability in FkoMko immortalized cells treated with DNA damaging agents. (a) Representative chromosomal aberrations scored (arrows). (b) Untreated immortalized fibroblasts: total aberrations, fragments and double minutes. Data represent the mean incidence per metaphase ±SD. **P < 0.005 for FkoMhet or FkoMko versus FhetMhet or FhetMko, †P < 0.05 for FkoMko or FkoMhet versus FhetMko or FhetMhet. (c) Immortalized fibroblasts exposed to mitomycin-C: total aberrations, fragments, breaks, radials and pulverized chromosomes. ***P < 0.001 for FkoMko or FkoMhet versus FhetMhet and FhetMko, †P < 0.05 for FkoMko versus FhetMhet or FhetMko, ±P < 0.05 for FkoMko versus FhetMhet, ††P < 0.01 for FkoMko versus FhetMhet or FhetMko. (d) Immortalized fibroblasts exposed to Ara-C: total aberrations, fragments and double minutes. *P < 0.05 for FkoMko versus FhetMhet, †P < 0.05 for FkoMhet or FkoMko versus FhetMhet or FhetMko, +P < 0.05 for FkoMhet versus FhetMko, ††P < 0.005 for FkoMko versus FhetMko and FhetMhet. All data analyzed by one-way ANOVA followed by Holm–Sidak post hoc.
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Figure 7: Genomic instability in FkoMko immortalized cells treated with DNA damaging agents. (a) Representative chromosomal aberrations scored (arrows). (b) Untreated immortalized fibroblasts: total aberrations, fragments and double minutes. Data represent the mean incidence per metaphase ±SD. **P < 0.005 for FkoMhet or FkoMko versus FhetMhet or FhetMko, †P < 0.05 for FkoMko or FkoMhet versus FhetMko or FhetMhet. (c) Immortalized fibroblasts exposed to mitomycin-C: total aberrations, fragments, breaks, radials and pulverized chromosomes. ***P < 0.001 for FkoMko or FkoMhet versus FhetMhet and FhetMko, †P < 0.05 for FkoMko versus FhetMhet or FhetMko, ±P < 0.05 for FkoMko versus FhetMhet, ††P < 0.01 for FkoMko versus FhetMhet or FhetMko. (d) Immortalized fibroblasts exposed to Ara-C: total aberrations, fragments and double minutes. *P < 0.05 for FkoMko versus FhetMhet, †P < 0.05 for FkoMhet or FkoMko versus FhetMhet or FhetMko, +P < 0.05 for FkoMhet versus FhetMko, ††P < 0.005 for FkoMko versus FhetMko and FhetMhet. All data analyzed by one-way ANOVA followed by Holm–Sidak post hoc.
Mentions: To determine whether the heightened repair defect in FkoMko cells reflects distinct contributions by FancC and Mus81 in the repair of specific lesions, we analyzed metaphase chromosomes from immortalized fibroblasts that were either untreated or exposed to either mitomycin-C or Ara-C (Figure 7). FkoMko-immortalized cells demonstrated a significantly higher number of chromosomal aberrations per metaphase than either FhetMhet (P < 0.001) or FhetMko (P = 0.001) cells, however they did not differ significantly from FkoMhet cells with regard to total aberrations. FkoMhet-immortalized fibroblasts demonstrated a significantly higher number of aberrations per metaphase than FhetMhet or FhetMko cells (P = 0.003; Figure 7B). Interestingly, pulverized chromosomes were not detected in untreated immortalized fibroblasts. Instead, significant changes in the incidence of aberrations were restricted to fragments and another distinct aberration appearing as paired chromosomal fragments or ‘double minutes’. The incidence of fragments was higher in both FkoMko and FkoMhet cells (P = 0.03 versus FhetMko and P = 0.02 versus FhetMhet), similarly incidence of double minutes was higher in FkoMko (P < 0.001 versus FhetMko and P = 0.001 versus FhetMhet) and FkoMhet cells (P = 0.009 versus FhetMko and P = 0.01 versus FhetMhet).

Bottom Line: Individuals with Fanconi anemia (FA) are susceptible to bone marrow failure, congenital abnormalities, cancer predisposition and exhibit defective DNA crosslink repair.This cooperativity of FancC and Mus81 in developmental outcome was also mirrored in response to crosslink damage and chromosomal integrity.Thus, our findings reveal that both pathways safeguard against DNA damage from exceeding a critical threshold that triggers proliferation arrest and apoptosis, leading to compromised in utero development.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Toxicology, University of Toronto, Toronto, M5S 1A8, Canada.

Show MeSH
Related in: MedlinePlus