Limits...
Rae1 is an essential mitotic checkpoint regulator that cooperates with Bub3 to prevent chromosome missegregation.

Babu JR, Jeganathan KB, Baker DJ, Wu X, Kang-Decker N, van Deursen JM - J. Cell Biol. (2003)

Bottom Line: Here we show that haplo-insufficiency of either Rae1 or Bub3 results in a similar phenotype involving mitotic checkpoint defects and chromosome missegregation.We also show that overexpression of Rae1 can correct for Rae1 haplo-insufficiency and, surprisingly, Bub3 haplo-insufficiency.Thus, our data demonstrate a novel function for Rae1 and characterize Rae1 and Bub3 as related proteins with essential, overlapping, and cooperating roles in the mitotic checkpoint.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN 55905, USA.

ABSTRACT
The WD-repeat proteins Rae1 and Bub3 show extensive sequence homology, indicative of functional similarity. However, previous studies have suggested that Rae1 is involved in the mRNA export pathway and Bub3 in the mitotic checkpoint. To determine the in vivo roles of Rae1 and Bub3 in mammals, we generated knockout mice that have these genes deleted individually or in combination. Here we show that haplo-insufficiency of either Rae1 or Bub3 results in a similar phenotype involving mitotic checkpoint defects and chromosome missegregation. We also show that overexpression of Rae1 can correct for Rae1 haplo-insufficiency and, surprisingly, Bub3 haplo-insufficiency. Rae1- and Bub3- mice are embryonic lethal, although cells from these mice did not have a detectable defect in nuclear export of mRNA. Unlike mice, compound haplo-insufficient Rae1/Bub3 mice are viable. However, cells from these mice exhibit much greater rates of premature sister chromatid separation and chromosome missegregation than single haplo-insufficient cells. Finally, we show that mice with mitotic checkpoint defects are more susceptible to dimethylbenzanthrene-induced tumorigenesis than wild-type mice. Thus, our data demonstrate a novel function for Rae1 and characterize Rae1 and Bub3 as related proteins with essential, overlapping, and cooperating roles in the mitotic checkpoint.

Show MeSH

Related in: MedlinePlus

Bub3+/− cells display increased chromosome number instability. (A) Analysis of the degree of aneuploidy in MEF cultures at passage 5. Values are from three independent Bub3+/+ and three independent Bub3+/− MEF cultures. 50 metaphase spreads were counted for each MEF culture. (B) Distribution of chromosome numbers of wild-type and Bub3 haplo-insufficient MEF lines (combined values of each genotype).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2172680&req=5

fig6: Bub3+/− cells display increased chromosome number instability. (A) Analysis of the degree of aneuploidy in MEF cultures at passage 5. Values are from three independent Bub3+/+ and three independent Bub3+/− MEF cultures. 50 metaphase spreads were counted for each MEF culture. (B) Distribution of chromosome numbers of wild-type and Bub3 haplo-insufficient MEF lines (combined values of each genotype).

Mentions: Next, we determined whether Bub3 haplo-insufficiency affects the fidelity of chromosome segregation in M phase. Chromosome counts on metaphase spreads revealed that the percentage of aneuploid cells was significantly higher in Bub3+/− cultures than in Bub3+/+ cultures (21 ± 2% vs. 9 ± 3%; Fig. 6 A; see also Fig. 8, B and D). Like Rae1+/− spreads, Bub3+/− spreads displayed a broader spectrum of nonmodal chromosome numbers than control spreads (Fig. 6 B; see also Fig. 8, B and D). Collectively, these studies reveal that the loss of a single Bub3 allele perturbs the mitotic checkpoint and establishes a higher rate of chromosome number instability.


Rae1 is an essential mitotic checkpoint regulator that cooperates with Bub3 to prevent chromosome missegregation.

Babu JR, Jeganathan KB, Baker DJ, Wu X, Kang-Decker N, van Deursen JM - J. Cell Biol. (2003)

Bub3+/− cells display increased chromosome number instability. (A) Analysis of the degree of aneuploidy in MEF cultures at passage 5. Values are from three independent Bub3+/+ and three independent Bub3+/− MEF cultures. 50 metaphase spreads were counted for each MEF culture. (B) Distribution of chromosome numbers of wild-type and Bub3 haplo-insufficient MEF lines (combined values of each genotype).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172680&req=5

fig6: Bub3+/− cells display increased chromosome number instability. (A) Analysis of the degree of aneuploidy in MEF cultures at passage 5. Values are from three independent Bub3+/+ and three independent Bub3+/− MEF cultures. 50 metaphase spreads were counted for each MEF culture. (B) Distribution of chromosome numbers of wild-type and Bub3 haplo-insufficient MEF lines (combined values of each genotype).
Mentions: Next, we determined whether Bub3 haplo-insufficiency affects the fidelity of chromosome segregation in M phase. Chromosome counts on metaphase spreads revealed that the percentage of aneuploid cells was significantly higher in Bub3+/− cultures than in Bub3+/+ cultures (21 ± 2% vs. 9 ± 3%; Fig. 6 A; see also Fig. 8, B and D). Like Rae1+/− spreads, Bub3+/− spreads displayed a broader spectrum of nonmodal chromosome numbers than control spreads (Fig. 6 B; see also Fig. 8, B and D). Collectively, these studies reveal that the loss of a single Bub3 allele perturbs the mitotic checkpoint and establishes a higher rate of chromosome number instability.

Bottom Line: Here we show that haplo-insufficiency of either Rae1 or Bub3 results in a similar phenotype involving mitotic checkpoint defects and chromosome missegregation.We also show that overexpression of Rae1 can correct for Rae1 haplo-insufficiency and, surprisingly, Bub3 haplo-insufficiency.Thus, our data demonstrate a novel function for Rae1 and characterize Rae1 and Bub3 as related proteins with essential, overlapping, and cooperating roles in the mitotic checkpoint.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN 55905, USA.

ABSTRACT
The WD-repeat proteins Rae1 and Bub3 show extensive sequence homology, indicative of functional similarity. However, previous studies have suggested that Rae1 is involved in the mRNA export pathway and Bub3 in the mitotic checkpoint. To determine the in vivo roles of Rae1 and Bub3 in mammals, we generated knockout mice that have these genes deleted individually or in combination. Here we show that haplo-insufficiency of either Rae1 or Bub3 results in a similar phenotype involving mitotic checkpoint defects and chromosome missegregation. We also show that overexpression of Rae1 can correct for Rae1 haplo-insufficiency and, surprisingly, Bub3 haplo-insufficiency. Rae1- and Bub3- mice are embryonic lethal, although cells from these mice did not have a detectable defect in nuclear export of mRNA. Unlike mice, compound haplo-insufficient Rae1/Bub3 mice are viable. However, cells from these mice exhibit much greater rates of premature sister chromatid separation and chromosome missegregation than single haplo-insufficient cells. Finally, we show that mice with mitotic checkpoint defects are more susceptible to dimethylbenzanthrene-induced tumorigenesis than wild-type mice. Thus, our data demonstrate a novel function for Rae1 and characterize Rae1 and Bub3 as related proteins with essential, overlapping, and cooperating roles in the mitotic checkpoint.

Show MeSH
Related in: MedlinePlus