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Repulsive cues combined with physical barriers and cell-cell adhesion determine progenitor cell positioning during organogenesis.

Paksa A, Bandemer J, Hoeckendorf B, Razin N, Tarbashevich K, Minina S, Meyen D, Biundo A, Leidel SA, Peyrieras N, Gov NS, Keller PJ, Raz E - Nat Commun (2016)

Bottom Line: Using primordial germ cells that participate in gonad formation, we present the developmental mechanisms maintaining a motile progenitor cell population at the site where the organ develops.Employing high-resolution live-cell microscopy, we find that repulsive cues coupled with physical barriers confine the cells to the correct bilateral positions.This analysis revealed that cell polarity changes on interaction with the physical barrier and that the establishment of compact clusters involves increased cell-cell interaction time.

View Article: PubMed Central - PubMed

Affiliation: Institute for Cell Biology, ZMBE, Von-Esmarch-Street 56, 48149 Muenster, Germany.

ABSTRACT
The precise positioning of organ progenitor cells constitutes an essential, yet poorly understood step during organogenesis. Using primordial germ cells that participate in gonad formation, we present the developmental mechanisms maintaining a motile progenitor cell population at the site where the organ develops. Employing high-resolution live-cell microscopy, we find that repulsive cues coupled with physical barriers confine the cells to the correct bilateral positions. This analysis revealed that cell polarity changes on interaction with the physical barrier and that the establishment of compact clusters involves increased cell-cell interaction time. Using particle-based simulations, we demonstrate the role of reflecting barriers, from which cells turn away on contact, and the importance of proper cell-cell adhesion level for maintaining the tight cell clusters and their correct positioning at the target region. The combination of these developmental and cellular mechanisms prevents organ fusion, controls organ positioning and is thus critical for its proper function.

No MeSH data available.


Related in: MedlinePlus

Lack of the developing gut causes PGC cluster fusion.(a) Whole-mount in situ hybridization on 30 hpf wild-type (N=420) and sox32 mutant embryos (N=89). PGCs are labelled with nanos3 (nos3, arrows) and the gut with foxa3 probe (arrowhead, missing in sox32 mutant embryos), both in blue. Unlike the separated PGC clusters in wild-type embryos, clusters are fused at the midline in sox32 mutant embryos (upper and lower panel images, respectively). Lateral (left panels) and dorsal (right panels) views are shown. (b) Cross-sections of 28 hpf sox17:dsred transgenic embryos whose gut is labelled in red and the PGCs membrane with EGFP. In control embryos (upper panel; N=5) bilateral PGC clusters form on either side of the gut tube. In embryos lacking the gut (Sox32-deficient; N=4) the PGC clusters fuse (lower panel). Nuclei counterstained with Hoechst. Scale bars, 25 μm. (c) Generation of mosaic embryos lacking Sox32 function in all cells whose endoderm is restored by providing Sox17 function to a group of cells (Scheme). The Sox32-deficient PGC clusters (green) are separated by the gut tissue at 28 hpf (red in lower panel, arrow; N=13), while in control embryos lacking endodermal tissues fused PGC clusters are observed (upper panel; N=24). Anterior is up. (d) PGC clusters in wild-type (N=20) and sox32 mutant (N=7) embryos lacking the gut tissue at 18, 24 and 28 hpf showing the dynamics of the fusion. N is the number of embryos analysed. Scale bar, 50 μm. Anterior is up.
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f5: Lack of the developing gut causes PGC cluster fusion.(a) Whole-mount in situ hybridization on 30 hpf wild-type (N=420) and sox32 mutant embryos (N=89). PGCs are labelled with nanos3 (nos3, arrows) and the gut with foxa3 probe (arrowhead, missing in sox32 mutant embryos), both in blue. Unlike the separated PGC clusters in wild-type embryos, clusters are fused at the midline in sox32 mutant embryos (upper and lower panel images, respectively). Lateral (left panels) and dorsal (right panels) views are shown. (b) Cross-sections of 28 hpf sox17:dsred transgenic embryos whose gut is labelled in red and the PGCs membrane with EGFP. In control embryos (upper panel; N=5) bilateral PGC clusters form on either side of the gut tube. In embryos lacking the gut (Sox32-deficient; N=4) the PGC clusters fuse (lower panel). Nuclei counterstained with Hoechst. Scale bars, 25 μm. (c) Generation of mosaic embryos lacking Sox32 function in all cells whose endoderm is restored by providing Sox17 function to a group of cells (Scheme). The Sox32-deficient PGC clusters (green) are separated by the gut tissue at 28 hpf (red in lower panel, arrow; N=13), while in control embryos lacking endodermal tissues fused PGC clusters are observed (upper panel; N=24). Anterior is up. (d) PGC clusters in wild-type (N=20) and sox32 mutant (N=7) embryos lacking the gut tissue at 18, 24 and 28 hpf showing the dynamics of the fusion. N is the number of embryos analysed. Scale bar, 50 μm. Anterior is up.

Mentions: Maintaining a bilateral organization of separated PGC clusters following arrival of the cells at the region where the gonad develops could in principle be achieved by the presence of medial structures that would prevent PGC migration towards the midline. We addressed this possibility by examining the positioning of the cell clusters in embryos lacking different midline structures. We found that in embryos lacking the vasculature or the notochord, the positioning of the PGC clusters was not affected (in cloche and floating head mutant embryos respectively, Supplementary Fig. 10). Conversely, a complete fusion between the two cell groups was invariably observed in embryos in which endoderm development was blocked, such that the developing gut was not positioned in between the two PGC clusters (that is, in casanova mutants lacking the function of the Sox32 protein4041, Fig. 5a,b).


Repulsive cues combined with physical barriers and cell-cell adhesion determine progenitor cell positioning during organogenesis.

Paksa A, Bandemer J, Hoeckendorf B, Razin N, Tarbashevich K, Minina S, Meyen D, Biundo A, Leidel SA, Peyrieras N, Gov NS, Keller PJ, Raz E - Nat Commun (2016)

Lack of the developing gut causes PGC cluster fusion.(a) Whole-mount in situ hybridization on 30 hpf wild-type (N=420) and sox32 mutant embryos (N=89). PGCs are labelled with nanos3 (nos3, arrows) and the gut with foxa3 probe (arrowhead, missing in sox32 mutant embryos), both in blue. Unlike the separated PGC clusters in wild-type embryos, clusters are fused at the midline in sox32 mutant embryos (upper and lower panel images, respectively). Lateral (left panels) and dorsal (right panels) views are shown. (b) Cross-sections of 28 hpf sox17:dsred transgenic embryos whose gut is labelled in red and the PGCs membrane with EGFP. In control embryos (upper panel; N=5) bilateral PGC clusters form on either side of the gut tube. In embryos lacking the gut (Sox32-deficient; N=4) the PGC clusters fuse (lower panel). Nuclei counterstained with Hoechst. Scale bars, 25 μm. (c) Generation of mosaic embryos lacking Sox32 function in all cells whose endoderm is restored by providing Sox17 function to a group of cells (Scheme). The Sox32-deficient PGC clusters (green) are separated by the gut tissue at 28 hpf (red in lower panel, arrow; N=13), while in control embryos lacking endodermal tissues fused PGC clusters are observed (upper panel; N=24). Anterior is up. (d) PGC clusters in wild-type (N=20) and sox32 mutant (N=7) embryos lacking the gut tissue at 18, 24 and 28 hpf showing the dynamics of the fusion. N is the number of embryos analysed. Scale bar, 50 μm. Anterior is up.
© Copyright Policy - open-access
Related In: Results  -  Collection

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f5: Lack of the developing gut causes PGC cluster fusion.(a) Whole-mount in situ hybridization on 30 hpf wild-type (N=420) and sox32 mutant embryos (N=89). PGCs are labelled with nanos3 (nos3, arrows) and the gut with foxa3 probe (arrowhead, missing in sox32 mutant embryos), both in blue. Unlike the separated PGC clusters in wild-type embryos, clusters are fused at the midline in sox32 mutant embryos (upper and lower panel images, respectively). Lateral (left panels) and dorsal (right panels) views are shown. (b) Cross-sections of 28 hpf sox17:dsred transgenic embryos whose gut is labelled in red and the PGCs membrane with EGFP. In control embryos (upper panel; N=5) bilateral PGC clusters form on either side of the gut tube. In embryos lacking the gut (Sox32-deficient; N=4) the PGC clusters fuse (lower panel). Nuclei counterstained with Hoechst. Scale bars, 25 μm. (c) Generation of mosaic embryos lacking Sox32 function in all cells whose endoderm is restored by providing Sox17 function to a group of cells (Scheme). The Sox32-deficient PGC clusters (green) are separated by the gut tissue at 28 hpf (red in lower panel, arrow; N=13), while in control embryos lacking endodermal tissues fused PGC clusters are observed (upper panel; N=24). Anterior is up. (d) PGC clusters in wild-type (N=20) and sox32 mutant (N=7) embryos lacking the gut tissue at 18, 24 and 28 hpf showing the dynamics of the fusion. N is the number of embryos analysed. Scale bar, 50 μm. Anterior is up.
Mentions: Maintaining a bilateral organization of separated PGC clusters following arrival of the cells at the region where the gonad develops could in principle be achieved by the presence of medial structures that would prevent PGC migration towards the midline. We addressed this possibility by examining the positioning of the cell clusters in embryos lacking different midline structures. We found that in embryos lacking the vasculature or the notochord, the positioning of the PGC clusters was not affected (in cloche and floating head mutant embryos respectively, Supplementary Fig. 10). Conversely, a complete fusion between the two cell groups was invariably observed in embryos in which endoderm development was blocked, such that the developing gut was not positioned in between the two PGC clusters (that is, in casanova mutants lacking the function of the Sox32 protein4041, Fig. 5a,b).

Bottom Line: Using primordial germ cells that participate in gonad formation, we present the developmental mechanisms maintaining a motile progenitor cell population at the site where the organ develops.Employing high-resolution live-cell microscopy, we find that repulsive cues coupled with physical barriers confine the cells to the correct bilateral positions.This analysis revealed that cell polarity changes on interaction with the physical barrier and that the establishment of compact clusters involves increased cell-cell interaction time.

View Article: PubMed Central - PubMed

Affiliation: Institute for Cell Biology, ZMBE, Von-Esmarch-Street 56, 48149 Muenster, Germany.

ABSTRACT
The precise positioning of organ progenitor cells constitutes an essential, yet poorly understood step during organogenesis. Using primordial germ cells that participate in gonad formation, we present the developmental mechanisms maintaining a motile progenitor cell population at the site where the organ develops. Employing high-resolution live-cell microscopy, we find that repulsive cues coupled with physical barriers confine the cells to the correct bilateral positions. This analysis revealed that cell polarity changes on interaction with the physical barrier and that the establishment of compact clusters involves increased cell-cell interaction time. Using particle-based simulations, we demonstrate the role of reflecting barriers, from which cells turn away on contact, and the importance of proper cell-cell adhesion level for maintaining the tight cell clusters and their correct positioning at the target region. The combination of these developmental and cellular mechanisms prevents organ fusion, controls organ positioning and is thus critical for its proper function.

No MeSH data available.


Related in: MedlinePlus