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Rac-GTPases Regulate Microtubule Stability and Axon Growth of Cortical GABAergic Interneurons.

Tivodar S, Kalemaki K, Kounoupa Z, Vidaki M, Theodorakis K, Denaxa M, Kessaris N, de Curtis I, Pachnis V, Karagogeos D - Cereb. Cortex (2014)

Bottom Line: We show that in the absence of both Rac proteins, the embryonic migration of medial ganglionic eminence-derived interneurons is further impaired.In addition, Rac1/Rac3-deficient interneurons show gross cytoskeletal defects in vitro, with the length of their leading processes significantly reduced and a clear multipolar morphology.We propose that in the absence of Rac1/Rac3, cortical interneurons fail to migrate tangentially towards the pallium due to defects in actin and microtubule cytoskeletal dynamics.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Biology and Biotechnology (IMBB, FORTH), Heraklion, Greece Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion, Greece.

No MeSH data available.


Related in: MedlinePlus

Cell autonomous migration defect of MGE-derived Rac1 and Rac1/Rac3-deficient interneurons. Matrigel explants from E13.5 control (A, A′: Rac1+/fl;Rac3+/−;Nkx2.1+/Cre, dhet), Rac1 mutant (B, B′: Rac1fl/fl;Rac3+/−;Nkx2.1+/Cre, Rac1mut), Rac3 mutant (C, C′: Rac1+/fl;Rac3−/−;Nkx2.1+/Cre, Rac3mut) and double mutant (D, D′: Rac1fl/fl;Rac3−/−;Nkx2.1+/Cre, dmut) embryos were included in matrigel and cell migration was monitored. After 24 h very few cells were migrating away from the Rac1 mutant and Rac1/Rac3 mutant explants (B, D) compared with the control or Rac3 mutant explants (A, C). Reduced migration was observed after 48 h in Rac1 mutant and double-mutant cultures (B′, D′). The distance of the neurons positioned furthest away from the explants was measured, and statistical significance was assessed, using Student's t-test (P value ; n = 10). Error bars represent the standard error of mean (E, E′). Scale bars: 50 μm.
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BHU037F2: Cell autonomous migration defect of MGE-derived Rac1 and Rac1/Rac3-deficient interneurons. Matrigel explants from E13.5 control (A, A′: Rac1+/fl;Rac3+/−;Nkx2.1+/Cre, dhet), Rac1 mutant (B, B′: Rac1fl/fl;Rac3+/−;Nkx2.1+/Cre, Rac1mut), Rac3 mutant (C, C′: Rac1+/fl;Rac3−/−;Nkx2.1+/Cre, Rac3mut) and double mutant (D, D′: Rac1fl/fl;Rac3−/−;Nkx2.1+/Cre, dmut) embryos were included in matrigel and cell migration was monitored. After 24 h very few cells were migrating away from the Rac1 mutant and Rac1/Rac3 mutant explants (B, D) compared with the control or Rac3 mutant explants (A, C). Reduced migration was observed after 48 h in Rac1 mutant and double-mutant cultures (B′, D′). The distance of the neurons positioned furthest away from the explants was measured, and statistical significance was assessed, using Student's t-test (P value ; n = 10). Error bars represent the standard error of mean (E, E′). Scale bars: 50 μm.

Mentions: To further study the migrating behavior of double-mutant cells and investigate whether the observed defects are cell autonomous, we cultured MGE explants on matrigel and analyzed the migration of cells out of the explants. MGE explants were collected from 4 different genotypes: control, Rac1 mutant, Rac3 mutant, and double mutant (see Materials and Methods section describing mice). After 24 h, explants from control or Rac3 mutant (Fig. 2A,C) looked similar, with cells migrating from the explant and forming a characteristic halo. Rac1 mutant cells were delayed in leaving the explants (Fig. 2B) as described in Vidaki et al. (2012). In double-mutant explants, even fewer cells were migrating for a short distance from the explant compared with the Rac1 mutant (Fig. 2D,E) at 24 h. At 48 h, while the control and Rac3 mutant cells were covering comparable areas (Fig. 2A′,C′) the distance traveled by the Rac1 mutant and the double-mutant cells (Fig. 2B′,D′) was significantly shorter, with the double-mutant cells covering the least distance of all genotypes (Fig. 2E′). The differences in distance traveled of double-mutant cells compared with control and Rac1 mutant alone is statistically significant (Fig. 2E,E′). We observed in our preliminary live imaging experiments that the emerging cells from the double-mutant MGE explants were less motile and did not display the characteristic growth cone extension/retraction movements (data not shown). Thus we consider that the delay in migration may be related to morphological and cytoskeletal abnormalities.Figure 2.


Rac-GTPases Regulate Microtubule Stability and Axon Growth of Cortical GABAergic Interneurons.

Tivodar S, Kalemaki K, Kounoupa Z, Vidaki M, Theodorakis K, Denaxa M, Kessaris N, de Curtis I, Pachnis V, Karagogeos D - Cereb. Cortex (2014)

Cell autonomous migration defect of MGE-derived Rac1 and Rac1/Rac3-deficient interneurons. Matrigel explants from E13.5 control (A, A′: Rac1+/fl;Rac3+/−;Nkx2.1+/Cre, dhet), Rac1 mutant (B, B′: Rac1fl/fl;Rac3+/−;Nkx2.1+/Cre, Rac1mut), Rac3 mutant (C, C′: Rac1+/fl;Rac3−/−;Nkx2.1+/Cre, Rac3mut) and double mutant (D, D′: Rac1fl/fl;Rac3−/−;Nkx2.1+/Cre, dmut) embryos were included in matrigel and cell migration was monitored. After 24 h very few cells were migrating away from the Rac1 mutant and Rac1/Rac3 mutant explants (B, D) compared with the control or Rac3 mutant explants (A, C). Reduced migration was observed after 48 h in Rac1 mutant and double-mutant cultures (B′, D′). The distance of the neurons positioned furthest away from the explants was measured, and statistical significance was assessed, using Student's t-test (P value ; n = 10). Error bars represent the standard error of mean (E, E′). Scale bars: 50 μm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4537417&req=5

BHU037F2: Cell autonomous migration defect of MGE-derived Rac1 and Rac1/Rac3-deficient interneurons. Matrigel explants from E13.5 control (A, A′: Rac1+/fl;Rac3+/−;Nkx2.1+/Cre, dhet), Rac1 mutant (B, B′: Rac1fl/fl;Rac3+/−;Nkx2.1+/Cre, Rac1mut), Rac3 mutant (C, C′: Rac1+/fl;Rac3−/−;Nkx2.1+/Cre, Rac3mut) and double mutant (D, D′: Rac1fl/fl;Rac3−/−;Nkx2.1+/Cre, dmut) embryos were included in matrigel and cell migration was monitored. After 24 h very few cells were migrating away from the Rac1 mutant and Rac1/Rac3 mutant explants (B, D) compared with the control or Rac3 mutant explants (A, C). Reduced migration was observed after 48 h in Rac1 mutant and double-mutant cultures (B′, D′). The distance of the neurons positioned furthest away from the explants was measured, and statistical significance was assessed, using Student's t-test (P value ; n = 10). Error bars represent the standard error of mean (E, E′). Scale bars: 50 μm.
Mentions: To further study the migrating behavior of double-mutant cells and investigate whether the observed defects are cell autonomous, we cultured MGE explants on matrigel and analyzed the migration of cells out of the explants. MGE explants were collected from 4 different genotypes: control, Rac1 mutant, Rac3 mutant, and double mutant (see Materials and Methods section describing mice). After 24 h, explants from control or Rac3 mutant (Fig. 2A,C) looked similar, with cells migrating from the explant and forming a characteristic halo. Rac1 mutant cells were delayed in leaving the explants (Fig. 2B) as described in Vidaki et al. (2012). In double-mutant explants, even fewer cells were migrating for a short distance from the explant compared with the Rac1 mutant (Fig. 2D,E) at 24 h. At 48 h, while the control and Rac3 mutant cells were covering comparable areas (Fig. 2A′,C′) the distance traveled by the Rac1 mutant and the double-mutant cells (Fig. 2B′,D′) was significantly shorter, with the double-mutant cells covering the least distance of all genotypes (Fig. 2E′). The differences in distance traveled of double-mutant cells compared with control and Rac1 mutant alone is statistically significant (Fig. 2E,E′). We observed in our preliminary live imaging experiments that the emerging cells from the double-mutant MGE explants were less motile and did not display the characteristic growth cone extension/retraction movements (data not shown). Thus we consider that the delay in migration may be related to morphological and cytoskeletal abnormalities.Figure 2.

Bottom Line: We show that in the absence of both Rac proteins, the embryonic migration of medial ganglionic eminence-derived interneurons is further impaired.In addition, Rac1/Rac3-deficient interneurons show gross cytoskeletal defects in vitro, with the length of their leading processes significantly reduced and a clear multipolar morphology.We propose that in the absence of Rac1/Rac3, cortical interneurons fail to migrate tangentially towards the pallium due to defects in actin and microtubule cytoskeletal dynamics.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Biology and Biotechnology (IMBB, FORTH), Heraklion, Greece Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion, Greece.

No MeSH data available.


Related in: MedlinePlus