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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

The distribution and the amount of Ac-Tubulin are different in the Rac1/Rac3-deficient MGE-derived cells. Cells cultured on collagen-coated coverslips were stained with antibodies against: YFP, Ac-Tubulin, and Ty-Tubulin (A, B). A′, B′, A″ and B″ represent high magnification of the boxed areas in A, B. (C) Quantification of Ac-Tub+ neurites at AIS showed a decrease in double-mutant cells. The Ac-Tubulin amount was determined after western blot analysis using MGE-derived cells (D) and statistical significance was assessed, using Student's t-test (P value < 0.05). Error bars represent the standard error of mean. Scale bars A and B: 75 μm; A′, B′, A″, and B″: 20 μm.
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BHU037F7: The distribution and the amount of Ac-Tubulin are different in the Rac1/Rac3-deficient MGE-derived cells. Cells cultured on collagen-coated coverslips were stained with antibodies against: YFP, Ac-Tubulin, and Ty-Tubulin (A, B). A′, B′, A″ and B″ represent high magnification of the boxed areas in A, B. (C) Quantification of Ac-Tub+ neurites at AIS showed a decrease in double-mutant cells. The Ac-Tubulin amount was determined after western blot analysis using MGE-derived cells (D) and statistical significance was assessed, using Student's t-test (P value < 0.05). Error bars represent the standard error of mean. Scale bars A and B: 75 μm; A′, B′, A″, and B″: 20 μm.

Mentions: Post-translational modifications such as tubulin acetylation are correlated with stable microtubules, enriched in the proximal part of axons and at the tip of the leading processes (Janke and Kneussel 2010). We looked for the stability of microtubules in our cultures and found that the signal for Ac-Tubulin was enriched at the axon initial segment and cell body in the cells isolated from the MGE of control animals, but this was not the case in the Rac1/Rac3-deficient cells (Fig. 7A′–B′,C). Moreover western blot analysis showed that the amount of Ac-Tubulin was reduced in protein extracts from double-mutant MGE-derived cells (Fig. 7D). These data are consistent with the hypothesis that in the absence of Rac1/Rac3 proteins the stability of microtubules is affected and this, along with the actin defects reported above (Fig. 5), could cause the morphological defects of leading processes.Figure 7.


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)

The distribution and the amount of Ac-Tubulin are different in the Rac1/Rac3-deficient MGE-derived cells. Cells cultured on collagen-coated coverslips were stained with antibodies against: YFP, Ac-Tubulin, and Ty-Tubulin (A, B). A′, B′, A″ and B″ represent high magnification of the boxed areas in A, B. (C) Quantification of Ac-Tub+ neurites at AIS showed a decrease in double-mutant cells. The Ac-Tubulin amount was determined after western blot analysis using MGE-derived cells (D) and statistical significance was assessed, using Student's t-test (P value < 0.05). Error bars represent the standard error of mean. Scale bars A and B: 75 μm; A′, B′, A″, and B″: 20 μm.
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Related In: Results  -  Collection

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BHU037F7: The distribution and the amount of Ac-Tubulin are different in the Rac1/Rac3-deficient MGE-derived cells. Cells cultured on collagen-coated coverslips were stained with antibodies against: YFP, Ac-Tubulin, and Ty-Tubulin (A, B). A′, B′, A″ and B″ represent high magnification of the boxed areas in A, B. (C) Quantification of Ac-Tub+ neurites at AIS showed a decrease in double-mutant cells. The Ac-Tubulin amount was determined after western blot analysis using MGE-derived cells (D) and statistical significance was assessed, using Student's t-test (P value < 0.05). Error bars represent the standard error of mean. Scale bars A and B: 75 μm; A′, B′, A″, and B″: 20 μm.
Mentions: Post-translational modifications such as tubulin acetylation are correlated with stable microtubules, enriched in the proximal part of axons and at the tip of the leading processes (Janke and Kneussel 2010). We looked for the stability of microtubules in our cultures and found that the signal for Ac-Tubulin was enriched at the axon initial segment and cell body in the cells isolated from the MGE of control animals, but this was not the case in the Rac1/Rac3-deficient cells (Fig. 7A′–B′,C). Moreover western blot analysis showed that the amount of Ac-Tubulin was reduced in protein extracts from double-mutant MGE-derived cells (Fig. 7D). These data are consistent with the hypothesis that in the absence of Rac1/Rac3 proteins the stability of microtubules is affected and this, along with the actin defects reported above (Fig. 5), could cause the morphological defects of leading processes.Figure 7.

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