Limits...
Foxc1 dependent mesenchymal signalling drives embryonic cerebellar growth.

Haldipur P, Gillies GS, Janson OK, Chizhikov VV, Mithal DS, Miller RJ, Millen KJ - Elife (2014)

Bottom Line: In vitro, SDF1α, a direct Foxc1 target also expressed in the head mesenchyme, acts as a cerebellar radial glial mitogen and a chemoattractant for nascent Purkinje cells.SDF1α also rescues the Foxc1-/- phenotype.Our data emphasizes that the head mesenchyme exerts a considerable influence on early embryonic brain development and its disruption contributes to neurodevelopmental disorders in humans.

View Article: PubMed Central - PubMed

Affiliation: Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States.

ABSTRACT
Loss of Foxc1 is associated with Dandy-Walker malformation, the most common human cerebellar malformation characterized by cerebellar hypoplasia and an enlarged posterior fossa and fourth ventricle. Although expressed in the mouse posterior fossa mesenchyme, loss of Foxc1 non-autonomously induces a rapid and devastating decrease in embryonic cerebellar ventricular zone radial glial proliferation and concurrent increase in cerebellar neuronal differentiation. Subsequent migration of cerebellar neurons is disrupted, associated with disordered radial glial morphology. In vitro, SDF1α, a direct Foxc1 target also expressed in the head mesenchyme, acts as a cerebellar radial glial mitogen and a chemoattractant for nascent Purkinje cells. Its receptor, Cxcr4, is expressed in cerebellar radial glial cells and conditional Cxcr4 ablation with Nes-Cre mimics the Foxc1-/- cerebellar phenotype. SDF1α also rescues the Foxc1-/- phenotype. Our data emphasizes that the head mesenchyme exerts a considerable influence on early embryonic brain development and its disruption contributes to neurodevelopmental disorders in humans.

Show MeSH

Related in: MedlinePlus

Radial glial and Bergmann glial morphology is severely disrupted in Foxc1−/− mice.(A–H) Sagittal sections of the embryonic mouse cerebellum in WT (A, C, C′, E, G) and Foxc1  mutants (B, D, D′, F, H) at e13.5 (A, B), e15.5 (C–D′), e17.5 (E, F) and 19.5 (G, H) stained for Nestin. While radial glial fibers extended from the ventricular zone to the pial surface in the WT cerebellum (C, C′, arrows), in the Foxc1  mutant, fibers were discontinuous and did not extend all the way to the pial surface (D, D′, arrows). In the WT cerebellum, Bergmann glial fibers extended from the EGL to the PL at e17.5 (E) and e19.5 (G, L; arrows). The white straight line in (E) demarcates the anlage into two regions—an anterior (left) region where fibers extend from the VZ to the pia, and the other (right) where Bergmann glial fibers extend from the EGL to the IGL. In the Foxc1  mutant, these two zones were not apparent and fiber morphology was severely disrupted (F, H; arrows). (I) Graph showing the number of TUNEL positive cells that span the length of the cerebellar ventricular zone. The number of TUNEL positive cells in the ventricular zone of the Foxc1−/− cerebellum was significantly higher than WT at e13.5 and e15.5. Data represented as average number of TUNEL positive cells per section analysed ± s.e.m. *** indicates significance with respect to corresponding WT Control (p < 0.05). (J–M) Sagittal sections of the WT (J, L) and Foxc1−/− cerebellum (K, M) stained for BLBP. In the e19.5 WT cerebellum (J, box; L, arrow), BG were present as a layer overlapping with the PL. However, in the Foxc1  mutant, (K, box; M, arrow) BG were ectopically located in the EGL. Abbreviations used; NTZ—Nuclear Transitory Zone and VZ—Ventricular Zone. The white dashed line indicates the outer boundary of the EGL and the mesenchyme, while the yellow dotted line represents the cerebellar ventricular surface. The white straight line in Image E represents the boundary between two zones—one where fibers extend from the VZ to the pia, and the other where BG fibers extend from the EGL to the IGL. C′–D′ are high magnification images of C–D respectively. Scale bar = 100 µm.DOI:http://dx.doi.org/10.7554/eLife.03962.007
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4281880&req=5

fig3: Radial glial and Bergmann glial morphology is severely disrupted in Foxc1−/− mice.(A–H) Sagittal sections of the embryonic mouse cerebellum in WT (A, C, C′, E, G) and Foxc1 mutants (B, D, D′, F, H) at e13.5 (A, B), e15.5 (C–D′), e17.5 (E, F) and 19.5 (G, H) stained for Nestin. While radial glial fibers extended from the ventricular zone to the pial surface in the WT cerebellum (C, C′, arrows), in the Foxc1 mutant, fibers were discontinuous and did not extend all the way to the pial surface (D, D′, arrows). In the WT cerebellum, Bergmann glial fibers extended from the EGL to the PL at e17.5 (E) and e19.5 (G, L; arrows). The white straight line in (E) demarcates the anlage into two regions—an anterior (left) region where fibers extend from the VZ to the pia, and the other (right) where Bergmann glial fibers extend from the EGL to the IGL. In the Foxc1 mutant, these two zones were not apparent and fiber morphology was severely disrupted (F, H; arrows). (I) Graph showing the number of TUNEL positive cells that span the length of the cerebellar ventricular zone. The number of TUNEL positive cells in the ventricular zone of the Foxc1−/− cerebellum was significantly higher than WT at e13.5 and e15.5. Data represented as average number of TUNEL positive cells per section analysed ± s.e.m. *** indicates significance with respect to corresponding WT Control (p < 0.05). (J–M) Sagittal sections of the WT (J, L) and Foxc1−/− cerebellum (K, M) stained for BLBP. In the e19.5 WT cerebellum (J, box; L, arrow), BG were present as a layer overlapping with the PL. However, in the Foxc1 mutant, (K, box; M, arrow) BG were ectopically located in the EGL. Abbreviations used; NTZ—Nuclear Transitory Zone and VZ—Ventricular Zone. The white dashed line indicates the outer boundary of the EGL and the mesenchyme, while the yellow dotted line represents the cerebellar ventricular surface. The white straight line in Image E represents the boundary between two zones—one where fibers extend from the VZ to the pia, and the other where BG fibers extend from the EGL to the IGL. C′–D′ are high magnification images of C–D respectively. Scale bar = 100 µm.DOI:http://dx.doi.org/10.7554/eLife.03962.007

Mentions: Since we observed dramatic Purkinje cell migration defects, we next examined the status of radial glial cells (Figure 3A–H) and Bergmann glia (Figure 3J–M). RG cells serve as both neuronal progenitors (Feng et al., 1994) and a scaffold for Purkinje cell neurons as they migrate towards the cerebellar cortex (Yuasa et al., 1996; Hatten, 1999) while BG serve as a scaffold for migrating granule neurons from the EGL. In wild-type animals at e13.5 and e15.5, the nestin-positive soma of RG were located in the ventricular zone with radial fibers extending to the NTZ or pial surface (Figure 3A, arrows). By e15.5, plentiful nestin-positive radial glial fibers extending from the ventricular surface to the pial surface were apparent in the wild-type anterior cerebellar anlage (Figure 3C–C′, arrows). However, by e17.5, radial glial cells in the posterior wild-type anlage transitioned into Bergmann Glial cells with radial fibers spanning just the presumptive molecular layer in the developing cerebellar cortex (Li et al., 2014) (Figure 3E,G; arrows). In Foxc1−/− mutants at e13.5, nestin-positive staining was evident; however extended radial fibers were absent (Figure 3B). By e15.5 nestin-positive fibers were discontinuous with very few extending to the pial surface (Figure 3D,D′, arrows). A similar absence of long radial fibers was evident in the e17.5 mutant (Figure 3F, arrows). Additionally, Bergmann glial morphology and arrangement were found to be disrupted in the Foxc1−/− mutant (Figure 3F–H,J–M, Figure 3K,M; arrows). In the WT, BG were found to overlap with the PL (Figure 3E,G,J,L), while in the Foxc1−/− mutant cells were found to be present ectopically in the EGL and ML indicating abnormal migration (Figure 3K,M). These changes were accompanied by increased cell death in the ventricular zone of Foxc1−/− mutants as measured by TUNEL labeling (Figure 3I). Together, our results suggest that the disruption of radial glial migratory scaffold in Foxc1−/− mutants contributes to aberrant PC migratory phenotypes in Foxc1−/− mutant mice, which in turn also contribute to an abnormal BG phenotype.10.7554/eLife.03962.007Figure 3.Radial glial and Bergmann glial morphology is severely disrupted in Foxc1−/− mice.


Foxc1 dependent mesenchymal signalling drives embryonic cerebellar growth.

Haldipur P, Gillies GS, Janson OK, Chizhikov VV, Mithal DS, Miller RJ, Millen KJ - Elife (2014)

Radial glial and Bergmann glial morphology is severely disrupted in Foxc1−/− mice.(A–H) Sagittal sections of the embryonic mouse cerebellum in WT (A, C, C′, E, G) and Foxc1  mutants (B, D, D′, F, H) at e13.5 (A, B), e15.5 (C–D′), e17.5 (E, F) and 19.5 (G, H) stained for Nestin. While radial glial fibers extended from the ventricular zone to the pial surface in the WT cerebellum (C, C′, arrows), in the Foxc1  mutant, fibers were discontinuous and did not extend all the way to the pial surface (D, D′, arrows). In the WT cerebellum, Bergmann glial fibers extended from the EGL to the PL at e17.5 (E) and e19.5 (G, L; arrows). The white straight line in (E) demarcates the anlage into two regions—an anterior (left) region where fibers extend from the VZ to the pia, and the other (right) where Bergmann glial fibers extend from the EGL to the IGL. In the Foxc1  mutant, these two zones were not apparent and fiber morphology was severely disrupted (F, H; arrows). (I) Graph showing the number of TUNEL positive cells that span the length of the cerebellar ventricular zone. The number of TUNEL positive cells in the ventricular zone of the Foxc1−/− cerebellum was significantly higher than WT at e13.5 and e15.5. Data represented as average number of TUNEL positive cells per section analysed ± s.e.m. *** indicates significance with respect to corresponding WT Control (p < 0.05). (J–M) Sagittal sections of the WT (J, L) and Foxc1−/− cerebellum (K, M) stained for BLBP. In the e19.5 WT cerebellum (J, box; L, arrow), BG were present as a layer overlapping with the PL. However, in the Foxc1  mutant, (K, box; M, arrow) BG were ectopically located in the EGL. Abbreviations used; NTZ—Nuclear Transitory Zone and VZ—Ventricular Zone. The white dashed line indicates the outer boundary of the EGL and the mesenchyme, while the yellow dotted line represents the cerebellar ventricular surface. The white straight line in Image E represents the boundary between two zones—one where fibers extend from the VZ to the pia, and the other where BG fibers extend from the EGL to the IGL. C′–D′ are high magnification images of C–D respectively. Scale bar = 100 µm.DOI:http://dx.doi.org/10.7554/eLife.03962.007
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4281880&req=5

fig3: Radial glial and Bergmann glial morphology is severely disrupted in Foxc1−/− mice.(A–H) Sagittal sections of the embryonic mouse cerebellum in WT (A, C, C′, E, G) and Foxc1 mutants (B, D, D′, F, H) at e13.5 (A, B), e15.5 (C–D′), e17.5 (E, F) and 19.5 (G, H) stained for Nestin. While radial glial fibers extended from the ventricular zone to the pial surface in the WT cerebellum (C, C′, arrows), in the Foxc1 mutant, fibers were discontinuous and did not extend all the way to the pial surface (D, D′, arrows). In the WT cerebellum, Bergmann glial fibers extended from the EGL to the PL at e17.5 (E) and e19.5 (G, L; arrows). The white straight line in (E) demarcates the anlage into two regions—an anterior (left) region where fibers extend from the VZ to the pia, and the other (right) where Bergmann glial fibers extend from the EGL to the IGL. In the Foxc1 mutant, these two zones were not apparent and fiber morphology was severely disrupted (F, H; arrows). (I) Graph showing the number of TUNEL positive cells that span the length of the cerebellar ventricular zone. The number of TUNEL positive cells in the ventricular zone of the Foxc1−/− cerebellum was significantly higher than WT at e13.5 and e15.5. Data represented as average number of TUNEL positive cells per section analysed ± s.e.m. *** indicates significance with respect to corresponding WT Control (p < 0.05). (J–M) Sagittal sections of the WT (J, L) and Foxc1−/− cerebellum (K, M) stained for BLBP. In the e19.5 WT cerebellum (J, box; L, arrow), BG were present as a layer overlapping with the PL. However, in the Foxc1 mutant, (K, box; M, arrow) BG were ectopically located in the EGL. Abbreviations used; NTZ—Nuclear Transitory Zone and VZ—Ventricular Zone. The white dashed line indicates the outer boundary of the EGL and the mesenchyme, while the yellow dotted line represents the cerebellar ventricular surface. The white straight line in Image E represents the boundary between two zones—one where fibers extend from the VZ to the pia, and the other where BG fibers extend from the EGL to the IGL. C′–D′ are high magnification images of C–D respectively. Scale bar = 100 µm.DOI:http://dx.doi.org/10.7554/eLife.03962.007
Mentions: Since we observed dramatic Purkinje cell migration defects, we next examined the status of radial glial cells (Figure 3A–H) and Bergmann glia (Figure 3J–M). RG cells serve as both neuronal progenitors (Feng et al., 1994) and a scaffold for Purkinje cell neurons as they migrate towards the cerebellar cortex (Yuasa et al., 1996; Hatten, 1999) while BG serve as a scaffold for migrating granule neurons from the EGL. In wild-type animals at e13.5 and e15.5, the nestin-positive soma of RG were located in the ventricular zone with radial fibers extending to the NTZ or pial surface (Figure 3A, arrows). By e15.5, plentiful nestin-positive radial glial fibers extending from the ventricular surface to the pial surface were apparent in the wild-type anterior cerebellar anlage (Figure 3C–C′, arrows). However, by e17.5, radial glial cells in the posterior wild-type anlage transitioned into Bergmann Glial cells with radial fibers spanning just the presumptive molecular layer in the developing cerebellar cortex (Li et al., 2014) (Figure 3E,G; arrows). In Foxc1−/− mutants at e13.5, nestin-positive staining was evident; however extended radial fibers were absent (Figure 3B). By e15.5 nestin-positive fibers were discontinuous with very few extending to the pial surface (Figure 3D,D′, arrows). A similar absence of long radial fibers was evident in the e17.5 mutant (Figure 3F, arrows). Additionally, Bergmann glial morphology and arrangement were found to be disrupted in the Foxc1−/− mutant (Figure 3F–H,J–M, Figure 3K,M; arrows). In the WT, BG were found to overlap with the PL (Figure 3E,G,J,L), while in the Foxc1−/− mutant cells were found to be present ectopically in the EGL and ML indicating abnormal migration (Figure 3K,M). These changes were accompanied by increased cell death in the ventricular zone of Foxc1−/− mutants as measured by TUNEL labeling (Figure 3I). Together, our results suggest that the disruption of radial glial migratory scaffold in Foxc1−/− mutants contributes to aberrant PC migratory phenotypes in Foxc1−/− mutant mice, which in turn also contribute to an abnormal BG phenotype.10.7554/eLife.03962.007Figure 3.Radial glial and Bergmann glial morphology is severely disrupted in Foxc1−/− mice.

Bottom Line: In vitro, SDF1α, a direct Foxc1 target also expressed in the head mesenchyme, acts as a cerebellar radial glial mitogen and a chemoattractant for nascent Purkinje cells.SDF1α also rescues the Foxc1-/- phenotype.Our data emphasizes that the head mesenchyme exerts a considerable influence on early embryonic brain development and its disruption contributes to neurodevelopmental disorders in humans.

View Article: PubMed Central - PubMed

Affiliation: Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States.

ABSTRACT
Loss of Foxc1 is associated with Dandy-Walker malformation, the most common human cerebellar malformation characterized by cerebellar hypoplasia and an enlarged posterior fossa and fourth ventricle. Although expressed in the mouse posterior fossa mesenchyme, loss of Foxc1 non-autonomously induces a rapid and devastating decrease in embryonic cerebellar ventricular zone radial glial proliferation and concurrent increase in cerebellar neuronal differentiation. Subsequent migration of cerebellar neurons is disrupted, associated with disordered radial glial morphology. In vitro, SDF1α, a direct Foxc1 target also expressed in the head mesenchyme, acts as a cerebellar radial glial mitogen and a chemoattractant for nascent Purkinje cells. Its receptor, Cxcr4, is expressed in cerebellar radial glial cells and conditional Cxcr4 ablation with Nes-Cre mimics the Foxc1-/- cerebellar phenotype. SDF1α also rescues the Foxc1-/- phenotype. Our data emphasizes that the head mesenchyme exerts a considerable influence on early embryonic brain development and its disruption contributes to neurodevelopmental disorders in humans.

Show MeSH
Related in: MedlinePlus