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Aneuploidy causes premature differentiation of neural and intestinal stem cells.

Gogendeau D, Siudeja K, Gambarotto D, Pennetier C, Bardin AJ, Basto R - Nat Commun (2015)

Bottom Line: We show that aneuploidy causes brain size reduction due to a decrease in the number of proliferative neural stem cells (NSCs), but not through apoptosis.Moreover, we show that this response to aneuploidy is also present in adult intestinal stem cells but not in the wing disc.Our work highlights a neural and intestine stem cell-specific response to aneuploidy, which prevents their proliferation and expansion.

View Article: PubMed Central - PubMed

Affiliation: Institut Curie, PSL Research University, CNRS UMR144, 12 rue Lhomond, Paris 75005, France.

ABSTRACT
Aneuploidy is associated with a variety of diseases such as cancer and microcephaly. Although many studies have addressed the consequences of a non-euploid genome in cells, little is known about their overall consequences in tissue and organism development. Here we use two different mutant conditions to address the consequences of aneuploidy during tissue development and homeostasis in Drosophila. We show that aneuploidy causes brain size reduction due to a decrease in the number of proliferative neural stem cells (NSCs), but not through apoptosis. Instead, aneuploid NSCs present an extended G1 phase, which leads to cell cycle exit and premature differentiation. Moreover, we show that this response to aneuploidy is also present in adult intestinal stem cells but not in the wing disc. Our work highlights a neural and intestine stem cell-specific response to aneuploidy, which prevents their proliferation and expansion.

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Related in: MedlinePlus

Apoptosis is not the cause of Nbs loss in aneuploid brains.(a) Schematic representation of L3 type I Nbs asymmetric divisions. The larger pink cell represents one Nb that asymmetrically segregates polarity cues and cell fate determinants. Spindle positioning along the polarity axis generates two daughter cells of unequal fate and size. The larger self-renewing cell, inherits the apical Par complex and Insc/Pins/Mud/Gαi complexes and maintains Nb identity whereas the small green daughter cell (the GMC) receives Numb, Pros and Brat, which promote differentiation and suppress self-renewal. The GMC divides once more to generate two terminally differentiated neurons or glial cells (purple cells). (b) Pictures of WT, SakOE,mad2 and bub3 L3 brain lobes stained for Deadpan (Dpn) a Nb marker. Aneuploid brains show a reduced number of Nbs in the CB region, highlighted by the yellow dashed line. Scale bar, 50μm. (c) Dot plot chart showing the quantification of Nbs number (Dpn+ cells) in WT (red dots, n=14 lobes), SakOE,mad2 (green dots, n=17 lobes) and bub3 (blue dots, n=32 lobes) CBs. Each dot represents a brain lobe. The line represents the mean and the error bars the s.d. Statistical significance (SS) was assessed by an unpaired t-test. ****(P<0.0001). (d) Pictures of WT, SakOE,mad2, bub3 and p35,bub3 L3 brain lobes stained with antibodies against cleaved caspase 3 (CC3, shown in red). DNA is shown in blue. The yellow dashed line marks the CB region. Scale bar, 50 μm. (e) Dot plot chart showing the quantification of the ratio between CC3 positive cells per CB area in WT (red dots), SakOE,mad2 (green dots), bub3 (blue dots) and p35, bub3 (blue circles) brains. Each dot represents the rate measured in each brain lobe. The line represents the mean and the error bars the s.d. SS**** was assessed by an unpaired t-test. **(P=0.005). (f) Dot plot chart showing the quantification of Nbs number in bub3 (full blue circles) and p35,bub3 brain lobes (empty blue circles) where apoptosis has been inhibited. The line represents the mean and the error bars the s.d. SS was assessed by an unpaired t-test.
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f2: Apoptosis is not the cause of Nbs loss in aneuploid brains.(a) Schematic representation of L3 type I Nbs asymmetric divisions. The larger pink cell represents one Nb that asymmetrically segregates polarity cues and cell fate determinants. Spindle positioning along the polarity axis generates two daughter cells of unequal fate and size. The larger self-renewing cell, inherits the apical Par complex and Insc/Pins/Mud/Gαi complexes and maintains Nb identity whereas the small green daughter cell (the GMC) receives Numb, Pros and Brat, which promote differentiation and suppress self-renewal. The GMC divides once more to generate two terminally differentiated neurons or glial cells (purple cells). (b) Pictures of WT, SakOE,mad2 and bub3 L3 brain lobes stained for Deadpan (Dpn) a Nb marker. Aneuploid brains show a reduced number of Nbs in the CB region, highlighted by the yellow dashed line. Scale bar, 50μm. (c) Dot plot chart showing the quantification of Nbs number (Dpn+ cells) in WT (red dots, n=14 lobes), SakOE,mad2 (green dots, n=17 lobes) and bub3 (blue dots, n=32 lobes) CBs. Each dot represents a brain lobe. The line represents the mean and the error bars the s.d. Statistical significance (SS) was assessed by an unpaired t-test. ****(P<0.0001). (d) Pictures of WT, SakOE,mad2, bub3 and p35,bub3 L3 brain lobes stained with antibodies against cleaved caspase 3 (CC3, shown in red). DNA is shown in blue. The yellow dashed line marks the CB region. Scale bar, 50 μm. (e) Dot plot chart showing the quantification of the ratio between CC3 positive cells per CB area in WT (red dots), SakOE,mad2 (green dots), bub3 (blue dots) and p35, bub3 (blue circles) brains. Each dot represents the rate measured in each brain lobe. The line represents the mean and the error bars the s.d. SS**** was assessed by an unpaired t-test. **(P=0.005). (f) Dot plot chart showing the quantification of Nbs number in bub3 (full blue circles) and p35,bub3 brain lobes (empty blue circles) where apoptosis has been inhibited. The line represents the mean and the error bars the s.d. SS was assessed by an unpaired t-test.

Mentions: SakOE,mad2 brains appeared smaller than WT brains (Fig. 1a) and we investigated the CB cell population. At early L3, previously quiescent type I Nbs re-enter the cell cycle and divide asymmetrically several times to self-renew91027 (Fig. 2a) generating around 100 daughter cells2829. SakOE,mad2 brains contained fewer Nbs positive for the Deadpan (Dpn) (Dpn+) marker when compared with WT brains (Fig. 2b,c). We then extended our analysis to the previously characterized aneuploid mutant with normal centrosome content, bub3 (refs 30, 31, 32). We used bub3 mutants because they die at the same developmental stage as SakOE,mad2 and bub3 Nbs display similar levels of aneuploidy although we did not detect polyploidy (Supplementary Fig. 2A,B). We characterized bub3 mitoses and found that all mitoses were bipolar (see below) and that frequently lagging chromosomes could be seen, as described before31. Similarly to SakOE,mad2 brains, we did not detect an increase in γ-H2Av-positive nuclei (Supplementary Fig. 2C,D). Importantly, we found that just like in SakOE,mad2 brains, the number of Nbs was reduced in bub3 mutant brains (Fig. 2b,c).


Aneuploidy causes premature differentiation of neural and intestinal stem cells.

Gogendeau D, Siudeja K, Gambarotto D, Pennetier C, Bardin AJ, Basto R - Nat Commun (2015)

Apoptosis is not the cause of Nbs loss in aneuploid brains.(a) Schematic representation of L3 type I Nbs asymmetric divisions. The larger pink cell represents one Nb that asymmetrically segregates polarity cues and cell fate determinants. Spindle positioning along the polarity axis generates two daughter cells of unequal fate and size. The larger self-renewing cell, inherits the apical Par complex and Insc/Pins/Mud/Gαi complexes and maintains Nb identity whereas the small green daughter cell (the GMC) receives Numb, Pros and Brat, which promote differentiation and suppress self-renewal. The GMC divides once more to generate two terminally differentiated neurons or glial cells (purple cells). (b) Pictures of WT, SakOE,mad2 and bub3 L3 brain lobes stained for Deadpan (Dpn) a Nb marker. Aneuploid brains show a reduced number of Nbs in the CB region, highlighted by the yellow dashed line. Scale bar, 50μm. (c) Dot plot chart showing the quantification of Nbs number (Dpn+ cells) in WT (red dots, n=14 lobes), SakOE,mad2 (green dots, n=17 lobes) and bub3 (blue dots, n=32 lobes) CBs. Each dot represents a brain lobe. The line represents the mean and the error bars the s.d. Statistical significance (SS) was assessed by an unpaired t-test. ****(P<0.0001). (d) Pictures of WT, SakOE,mad2, bub3 and p35,bub3 L3 brain lobes stained with antibodies against cleaved caspase 3 (CC3, shown in red). DNA is shown in blue. The yellow dashed line marks the CB region. Scale bar, 50 μm. (e) Dot plot chart showing the quantification of the ratio between CC3 positive cells per CB area in WT (red dots), SakOE,mad2 (green dots), bub3 (blue dots) and p35, bub3 (blue circles) brains. Each dot represents the rate measured in each brain lobe. The line represents the mean and the error bars the s.d. SS**** was assessed by an unpaired t-test. **(P=0.005). (f) Dot plot chart showing the quantification of Nbs number in bub3 (full blue circles) and p35,bub3 brain lobes (empty blue circles) where apoptosis has been inhibited. The line represents the mean and the error bars the s.d. SS was assessed by an unpaired t-test.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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f2: Apoptosis is not the cause of Nbs loss in aneuploid brains.(a) Schematic representation of L3 type I Nbs asymmetric divisions. The larger pink cell represents one Nb that asymmetrically segregates polarity cues and cell fate determinants. Spindle positioning along the polarity axis generates two daughter cells of unequal fate and size. The larger self-renewing cell, inherits the apical Par complex and Insc/Pins/Mud/Gαi complexes and maintains Nb identity whereas the small green daughter cell (the GMC) receives Numb, Pros and Brat, which promote differentiation and suppress self-renewal. The GMC divides once more to generate two terminally differentiated neurons or glial cells (purple cells). (b) Pictures of WT, SakOE,mad2 and bub3 L3 brain lobes stained for Deadpan (Dpn) a Nb marker. Aneuploid brains show a reduced number of Nbs in the CB region, highlighted by the yellow dashed line. Scale bar, 50μm. (c) Dot plot chart showing the quantification of Nbs number (Dpn+ cells) in WT (red dots, n=14 lobes), SakOE,mad2 (green dots, n=17 lobes) and bub3 (blue dots, n=32 lobes) CBs. Each dot represents a brain lobe. The line represents the mean and the error bars the s.d. Statistical significance (SS) was assessed by an unpaired t-test. ****(P<0.0001). (d) Pictures of WT, SakOE,mad2, bub3 and p35,bub3 L3 brain lobes stained with antibodies against cleaved caspase 3 (CC3, shown in red). DNA is shown in blue. The yellow dashed line marks the CB region. Scale bar, 50 μm. (e) Dot plot chart showing the quantification of the ratio between CC3 positive cells per CB area in WT (red dots), SakOE,mad2 (green dots), bub3 (blue dots) and p35, bub3 (blue circles) brains. Each dot represents the rate measured in each brain lobe. The line represents the mean and the error bars the s.d. SS**** was assessed by an unpaired t-test. **(P=0.005). (f) Dot plot chart showing the quantification of Nbs number in bub3 (full blue circles) and p35,bub3 brain lobes (empty blue circles) where apoptosis has been inhibited. The line represents the mean and the error bars the s.d. SS was assessed by an unpaired t-test.
Mentions: SakOE,mad2 brains appeared smaller than WT brains (Fig. 1a) and we investigated the CB cell population. At early L3, previously quiescent type I Nbs re-enter the cell cycle and divide asymmetrically several times to self-renew91027 (Fig. 2a) generating around 100 daughter cells2829. SakOE,mad2 brains contained fewer Nbs positive for the Deadpan (Dpn) (Dpn+) marker when compared with WT brains (Fig. 2b,c). We then extended our analysis to the previously characterized aneuploid mutant with normal centrosome content, bub3 (refs 30, 31, 32). We used bub3 mutants because they die at the same developmental stage as SakOE,mad2 and bub3 Nbs display similar levels of aneuploidy although we did not detect polyploidy (Supplementary Fig. 2A,B). We characterized bub3 mitoses and found that all mitoses were bipolar (see below) and that frequently lagging chromosomes could be seen, as described before31. Similarly to SakOE,mad2 brains, we did not detect an increase in γ-H2Av-positive nuclei (Supplementary Fig. 2C,D). Importantly, we found that just like in SakOE,mad2 brains, the number of Nbs was reduced in bub3 mutant brains (Fig. 2b,c).

Bottom Line: We show that aneuploidy causes brain size reduction due to a decrease in the number of proliferative neural stem cells (NSCs), but not through apoptosis.Moreover, we show that this response to aneuploidy is also present in adult intestinal stem cells but not in the wing disc.Our work highlights a neural and intestine stem cell-specific response to aneuploidy, which prevents their proliferation and expansion.

View Article: PubMed Central - PubMed

Affiliation: Institut Curie, PSL Research University, CNRS UMR144, 12 rue Lhomond, Paris 75005, France.

ABSTRACT
Aneuploidy is associated with a variety of diseases such as cancer and microcephaly. Although many studies have addressed the consequences of a non-euploid genome in cells, little is known about their overall consequences in tissue and organism development. Here we use two different mutant conditions to address the consequences of aneuploidy during tissue development and homeostasis in Drosophila. We show that aneuploidy causes brain size reduction due to a decrease in the number of proliferative neural stem cells (NSCs), but not through apoptosis. Instead, aneuploid NSCs present an extended G1 phase, which leads to cell cycle exit and premature differentiation. Moreover, we show that this response to aneuploidy is also present in adult intestinal stem cells but not in the wing disc. Our work highlights a neural and intestine stem cell-specific response to aneuploidy, which prevents their proliferation and expansion.

Show MeSH
Related in: MedlinePlus