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Dll1 maintains quiescence of adult neural stem cells and segregates asymmetrically during mitosis.

Kawaguchi D, Furutachi S, Kawai H, Hozumi K, Gotoh Y - Nat Commun (2013)

Bottom Line: Dll1 protein is induced in activated NSCs and segregates to one daughter cell during mitosis.Dll1-expressing cells reside in close proximity to quiescent NSCs, suggesting a feedback signal for NSC maintenance by their sister cells and progeny.Our data suggest a model in which NSCs produce their own niche cells for their maintenance through asymmetric Dll1 inheritance at mitosis.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.

ABSTRACT
Stem cells often divide asymmetrically to produce one stem cell and one differentiating cell, thus maintaining the stem cell pool. Although neural stem cells (NSCs) in the adult mouse subventricular zone have been suggested to divide asymmetrically, intrinsic cell fate determinants for asymmetric NSC division are largely unknown. Stem cell niches are important for stem cell maintenance, but the niche for the maintenance of adult quiescent NSCs has remained obscure. Here we show that the Notch ligand Delta-like 1 (Dll1) is required to maintain quiescent NSCs in the adult mouse subventricular zone. Dll1 protein is induced in activated NSCs and segregates to one daughter cell during mitosis. Dll1-expressing cells reside in close proximity to quiescent NSCs, suggesting a feedback signal for NSC maintenance by their sister cells and progeny. Our data suggest a model in which NSCs produce their own niche cells for their maintenance through asymmetric Dll1 inheritance at mitosis.

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Quiescent NSCs positive for activated Notch are located adjacent to Dll1-expressing cells in the adult mouse SVZ.Mice injected daily with IdU for 15 days were examined 21 days after the last injection. (a) Sections of the SVZ were subjected to immunofluorescence staining of IdU (for detection of LRCs), NICD and Dll1. Nuclei were stained with Hoechst 33342. LV, lateral ventricle. Arrows indicate NICD+ IdU-LRCs, and arrowheads indicate Dll1+ cells. Broken lines indicate the ventricular surface. (b) The boxed region in a is shown at higher magnification. (c) The proportions of NICD+ cells among LRCs (i), of NICD– cells among Dll1+ cells (ii) and of LRCs (iii) or NICD+ LRCs (iv) that were adjacent to Dll1+ cells (within a distance of 10 μm between nuclei) are indicated (means±s.d., n=3 brains). Total counted cells were LRCs=101 (i, iii), Dll1-positive cells=86 (ii) and NICD-positive LRCs=78 (iv). Scale bar, 10 μm.
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f1: Quiescent NSCs positive for activated Notch are located adjacent to Dll1-expressing cells in the adult mouse SVZ.Mice injected daily with IdU for 15 days were examined 21 days after the last injection. (a) Sections of the SVZ were subjected to immunofluorescence staining of IdU (for detection of LRCs), NICD and Dll1. Nuclei were stained with Hoechst 33342. LV, lateral ventricle. Arrows indicate NICD+ IdU-LRCs, and arrowheads indicate Dll1+ cells. Broken lines indicate the ventricular surface. (b) The boxed region in a is shown at higher magnification. (c) The proportions of NICD+ cells among LRCs (i), of NICD– cells among Dll1+ cells (ii) and of LRCs (iii) or NICD+ LRCs (iv) that were adjacent to Dll1+ cells (within a distance of 10 μm between nuclei) are indicated (means±s.d., n=3 brains). Total counted cells were LRCs=101 (i, iii), Dll1-positive cells=86 (ii) and NICD-positive LRCs=78 (iv). Scale bar, 10 μm.

Mentions: The activation of Notch signalling in adult NSCs would be expected to require their interaction with cells expressing a Notch ligand. Given that Dll1 is a major ligand for Notch activation in NSCs of the embryonic telencephalon35, we examined whether Dll1-expressing cells also make contact with NSCs in the adult SVZ. Slowly dividing (or quiescent) adult NSCs can be detected as label-retaining cells (LRCs) after pulse-chase treatment with a nucleotide analogue such as iododeoxyuridine (IdU)436. Immunohistofluorescence staining revealed that most (80.9±13.8%) LRCs in the SVZ of the adult mouse forebrain were positive for the active form of Notch (NICD) (Fig. 1), confirming that Notch is activated in NSCs1226. We found that Dll1 exhibited a characteristic punctate staining pattern, which is thought to reflect the active state of Notch ligand373839, in a subset of SVZ cells in the adult mouse forebrain (Fig. 1) (a movie of three-dimensional (3D) reconstruction from confocal images is shown in Supplementary Movie 1). The disappearance of Dll1-immunostaining puncta in Dll1-deleted brains (Fig. 2a) and the detection of Dll1-immunostaining puncta in most Dll1-mRNA-expressing cells confirm the specificity of the antibody (Supplementary Fig. S1). Using this antibody, we found that most (96.3±1.1%) of the Dll1+ cells were NICD negative (Fig. 1). Importantly, Dll1+ cells were detected in close proximity (within a distance of 10 μm between nuclei) to most (84.4±7.2%) NICD+ LRCs (Fig. 1), suggesting that Dll1 might activate Notch in NSCs.


Dll1 maintains quiescence of adult neural stem cells and segregates asymmetrically during mitosis.

Kawaguchi D, Furutachi S, Kawai H, Hozumi K, Gotoh Y - Nat Commun (2013)

Quiescent NSCs positive for activated Notch are located adjacent to Dll1-expressing cells in the adult mouse SVZ.Mice injected daily with IdU for 15 days were examined 21 days after the last injection. (a) Sections of the SVZ were subjected to immunofluorescence staining of IdU (for detection of LRCs), NICD and Dll1. Nuclei were stained with Hoechst 33342. LV, lateral ventricle. Arrows indicate NICD+ IdU-LRCs, and arrowheads indicate Dll1+ cells. Broken lines indicate the ventricular surface. (b) The boxed region in a is shown at higher magnification. (c) The proportions of NICD+ cells among LRCs (i), of NICD– cells among Dll1+ cells (ii) and of LRCs (iii) or NICD+ LRCs (iv) that were adjacent to Dll1+ cells (within a distance of 10 μm between nuclei) are indicated (means±s.d., n=3 brains). Total counted cells were LRCs=101 (i, iii), Dll1-positive cells=86 (ii) and NICD-positive LRCs=78 (iv). Scale bar, 10 μm.
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Related In: Results  -  Collection

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f1: Quiescent NSCs positive for activated Notch are located adjacent to Dll1-expressing cells in the adult mouse SVZ.Mice injected daily with IdU for 15 days were examined 21 days after the last injection. (a) Sections of the SVZ were subjected to immunofluorescence staining of IdU (for detection of LRCs), NICD and Dll1. Nuclei were stained with Hoechst 33342. LV, lateral ventricle. Arrows indicate NICD+ IdU-LRCs, and arrowheads indicate Dll1+ cells. Broken lines indicate the ventricular surface. (b) The boxed region in a is shown at higher magnification. (c) The proportions of NICD+ cells among LRCs (i), of NICD– cells among Dll1+ cells (ii) and of LRCs (iii) or NICD+ LRCs (iv) that were adjacent to Dll1+ cells (within a distance of 10 μm between nuclei) are indicated (means±s.d., n=3 brains). Total counted cells were LRCs=101 (i, iii), Dll1-positive cells=86 (ii) and NICD-positive LRCs=78 (iv). Scale bar, 10 μm.
Mentions: The activation of Notch signalling in adult NSCs would be expected to require their interaction with cells expressing a Notch ligand. Given that Dll1 is a major ligand for Notch activation in NSCs of the embryonic telencephalon35, we examined whether Dll1-expressing cells also make contact with NSCs in the adult SVZ. Slowly dividing (or quiescent) adult NSCs can be detected as label-retaining cells (LRCs) after pulse-chase treatment with a nucleotide analogue such as iododeoxyuridine (IdU)436. Immunohistofluorescence staining revealed that most (80.9±13.8%) LRCs in the SVZ of the adult mouse forebrain were positive for the active form of Notch (NICD) (Fig. 1), confirming that Notch is activated in NSCs1226. We found that Dll1 exhibited a characteristic punctate staining pattern, which is thought to reflect the active state of Notch ligand373839, in a subset of SVZ cells in the adult mouse forebrain (Fig. 1) (a movie of three-dimensional (3D) reconstruction from confocal images is shown in Supplementary Movie 1). The disappearance of Dll1-immunostaining puncta in Dll1-deleted brains (Fig. 2a) and the detection of Dll1-immunostaining puncta in most Dll1-mRNA-expressing cells confirm the specificity of the antibody (Supplementary Fig. S1). Using this antibody, we found that most (96.3±1.1%) of the Dll1+ cells were NICD negative (Fig. 1). Importantly, Dll1+ cells were detected in close proximity (within a distance of 10 μm between nuclei) to most (84.4±7.2%) NICD+ LRCs (Fig. 1), suggesting that Dll1 might activate Notch in NSCs.

Bottom Line: Dll1 protein is induced in activated NSCs and segregates to one daughter cell during mitosis.Dll1-expressing cells reside in close proximity to quiescent NSCs, suggesting a feedback signal for NSC maintenance by their sister cells and progeny.Our data suggest a model in which NSCs produce their own niche cells for their maintenance through asymmetric Dll1 inheritance at mitosis.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.

ABSTRACT
Stem cells often divide asymmetrically to produce one stem cell and one differentiating cell, thus maintaining the stem cell pool. Although neural stem cells (NSCs) in the adult mouse subventricular zone have been suggested to divide asymmetrically, intrinsic cell fate determinants for asymmetric NSC division are largely unknown. Stem cell niches are important for stem cell maintenance, but the niche for the maintenance of adult quiescent NSCs has remained obscure. Here we show that the Notch ligand Delta-like 1 (Dll1) is required to maintain quiescent NSCs in the adult mouse subventricular zone. Dll1 protein is induced in activated NSCs and segregates to one daughter cell during mitosis. Dll1-expressing cells reside in close proximity to quiescent NSCs, suggesting a feedback signal for NSC maintenance by their sister cells and progeny. Our data suggest a model in which NSCs produce their own niche cells for their maintenance through asymmetric Dll1 inheritance at mitosis.

Show MeSH