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The crucial role of Atg5 in cortical neurogenesis during early brain development.

Lv X, Jiang H, Li B, Liang Q, Wang S, Zhao Q, Jiao J - Sci Rep (2014)

Bottom Line: The β-Catenin phosphorylation level decreased when Atg5 was blocked.Atg5 cooperated with β-Catenin to modulate cortical NPCs differentiation and proliferation.Our results revealed that Atg5 has a crucial role in cortical neurogenesis during early embryonic brain development, which may contribute to the understanding of neurodevelopmental disorders caused by autophagy dysregulation.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China [2].

ABSTRACT
Autophagy plays an important role in the central nervous system. However, it is unknown how autophagy regulates cortical neurogenesis during early brain development. Here, we report that autophagy-related gene 5 (Atg5) expression increased with cortical development and differentiation. The suppression of Atg5 expression by knockdown led to inhibited differentiation and increased proliferation of cortical neural progenitor cells (NPCs). Additionally, Atg5 suppression impaired cortical neuronal cell morphology. We lastly observed that Atg5 was involved in the regulation of the β-Catenin signaling pathway. The β-Catenin phosphorylation level decreased when Atg5 was blocked. Atg5 cooperated with β-Catenin to modulate cortical NPCs differentiation and proliferation. Our results revealed that Atg5 has a crucial role in cortical neurogenesis during early embryonic brain development, which may contribute to the understanding of neurodevelopmental disorders caused by autophagy dysregulation.

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Atg5 expression in the embryonic cerebral cortex.(a). A western blot shows the protein level of Atg5 in the mouse cortex during embryonic development. β-actin was used as a control. Blot images were cropped for comparison. (b). The bar graph shows the relative band intensity of Atg5 from embryonic day 10 to 16 (E10–E16). (c). The expression of Atg5 in the developing cortex. CP, cortical plate; IZ, intermediate zone; SVZ, subventricular zone; VZ, ventricular zone. Boxed areas are enlarged in the bottom. (d). Atg5 is co-localized with Sox2 in the VZ/SVZ of E15 brain sections. Boxed areas are enlarged in the bottom. (e). The protein levels of Atg5 and Tuj1were determined by a western blot in mouse neural stem cells over 7 days of differentiation. β-actin was used as a control. Blot images were cropped for comparison. (f, g).The bar graphs show the relative band intensity of Atg5 (f) and Tuj1 (g) in mouse neural stem cells during a differentiation time course. Scale bars, 50 μm (c and d).
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f1: Atg5 expression in the embryonic cerebral cortex.(a). A western blot shows the protein level of Atg5 in the mouse cortex during embryonic development. β-actin was used as a control. Blot images were cropped for comparison. (b). The bar graph shows the relative band intensity of Atg5 from embryonic day 10 to 16 (E10–E16). (c). The expression of Atg5 in the developing cortex. CP, cortical plate; IZ, intermediate zone; SVZ, subventricular zone; VZ, ventricular zone. Boxed areas are enlarged in the bottom. (d). Atg5 is co-localized with Sox2 in the VZ/SVZ of E15 brain sections. Boxed areas are enlarged in the bottom. (e). The protein levels of Atg5 and Tuj1were determined by a western blot in mouse neural stem cells over 7 days of differentiation. β-actin was used as a control. Blot images were cropped for comparison. (f, g).The bar graphs show the relative band intensity of Atg5 (f) and Tuj1 (g) in mouse neural stem cells during a differentiation time course. Scale bars, 50 μm (c and d).

Mentions: To determine the role of Atg5 in cortical development, we initially examined the expression of Atg5 in the embryonic cortex from embryonic day 10 to embryonic day 16 (E10–E16). A western blot revealed that Atg5 expression increased with embryonic developmental proceeding (Fig. 1a, b). To further investigate the results, we performed the experiments in vivo. The immunostaining results displayed higher expression of Atg5 in the cortical plate (CP), subventricular zone (SVZ), and ventricular zone (VZ) in the developing cortex but lower in the intermediate zone (IZ) (Fig. 1c). NPCs mainly reside in the VZ and SVZ2, which suggested the possibility of Atg5 expression in NPCs. To examine whether Atg5 was expressed in NPCs, we investigated Atg5 expression in Sox2-positive NPCs using E15 brain sections (Fig. 1d). Double immunostaining revealed that Atg5 was co-localized with Sox2 in the VZ/SVZ, suggesting that Atg5 has important roles in NPCs and may affect neuronal differentiation. To address this possibility, we examined the levels of Atg5 expression with neuronal differentiation. Primary neural stem cells were derived from E12 mouse brains and further cultured over 7 days in the differentiation medium. Notably, a western blot revealed that Atg5 expression increased in parallel with the upregulation of Tuj1 expression during the differentiation time course (Fig. 1e–g). These data suggested the potential roles of Atg5 in cortical NPCs differentiation.


The crucial role of Atg5 in cortical neurogenesis during early brain development.

Lv X, Jiang H, Li B, Liang Q, Wang S, Zhao Q, Jiao J - Sci Rep (2014)

Atg5 expression in the embryonic cerebral cortex.(a). A western blot shows the protein level of Atg5 in the mouse cortex during embryonic development. β-actin was used as a control. Blot images were cropped for comparison. (b). The bar graph shows the relative band intensity of Atg5 from embryonic day 10 to 16 (E10–E16). (c). The expression of Atg5 in the developing cortex. CP, cortical plate; IZ, intermediate zone; SVZ, subventricular zone; VZ, ventricular zone. Boxed areas are enlarged in the bottom. (d). Atg5 is co-localized with Sox2 in the VZ/SVZ of E15 brain sections. Boxed areas are enlarged in the bottom. (e). The protein levels of Atg5 and Tuj1were determined by a western blot in mouse neural stem cells over 7 days of differentiation. β-actin was used as a control. Blot images were cropped for comparison. (f, g).The bar graphs show the relative band intensity of Atg5 (f) and Tuj1 (g) in mouse neural stem cells during a differentiation time course. Scale bars, 50 μm (c and d).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4127499&req=5

f1: Atg5 expression in the embryonic cerebral cortex.(a). A western blot shows the protein level of Atg5 in the mouse cortex during embryonic development. β-actin was used as a control. Blot images were cropped for comparison. (b). The bar graph shows the relative band intensity of Atg5 from embryonic day 10 to 16 (E10–E16). (c). The expression of Atg5 in the developing cortex. CP, cortical plate; IZ, intermediate zone; SVZ, subventricular zone; VZ, ventricular zone. Boxed areas are enlarged in the bottom. (d). Atg5 is co-localized with Sox2 in the VZ/SVZ of E15 brain sections. Boxed areas are enlarged in the bottom. (e). The protein levels of Atg5 and Tuj1were determined by a western blot in mouse neural stem cells over 7 days of differentiation. β-actin was used as a control. Blot images were cropped for comparison. (f, g).The bar graphs show the relative band intensity of Atg5 (f) and Tuj1 (g) in mouse neural stem cells during a differentiation time course. Scale bars, 50 μm (c and d).
Mentions: To determine the role of Atg5 in cortical development, we initially examined the expression of Atg5 in the embryonic cortex from embryonic day 10 to embryonic day 16 (E10–E16). A western blot revealed that Atg5 expression increased with embryonic developmental proceeding (Fig. 1a, b). To further investigate the results, we performed the experiments in vivo. The immunostaining results displayed higher expression of Atg5 in the cortical plate (CP), subventricular zone (SVZ), and ventricular zone (VZ) in the developing cortex but lower in the intermediate zone (IZ) (Fig. 1c). NPCs mainly reside in the VZ and SVZ2, which suggested the possibility of Atg5 expression in NPCs. To examine whether Atg5 was expressed in NPCs, we investigated Atg5 expression in Sox2-positive NPCs using E15 brain sections (Fig. 1d). Double immunostaining revealed that Atg5 was co-localized with Sox2 in the VZ/SVZ, suggesting that Atg5 has important roles in NPCs and may affect neuronal differentiation. To address this possibility, we examined the levels of Atg5 expression with neuronal differentiation. Primary neural stem cells were derived from E12 mouse brains and further cultured over 7 days in the differentiation medium. Notably, a western blot revealed that Atg5 expression increased in parallel with the upregulation of Tuj1 expression during the differentiation time course (Fig. 1e–g). These data suggested the potential roles of Atg5 in cortical NPCs differentiation.

Bottom Line: The β-Catenin phosphorylation level decreased when Atg5 was blocked.Atg5 cooperated with β-Catenin to modulate cortical NPCs differentiation and proliferation.Our results revealed that Atg5 has a crucial role in cortical neurogenesis during early embryonic brain development, which may contribute to the understanding of neurodevelopmental disorders caused by autophagy dysregulation.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China [2].

ABSTRACT
Autophagy plays an important role in the central nervous system. However, it is unknown how autophagy regulates cortical neurogenesis during early brain development. Here, we report that autophagy-related gene 5 (Atg5) expression increased with cortical development and differentiation. The suppression of Atg5 expression by knockdown led to inhibited differentiation and increased proliferation of cortical neural progenitor cells (NPCs). Additionally, Atg5 suppression impaired cortical neuronal cell morphology. We lastly observed that Atg5 was involved in the regulation of the β-Catenin signaling pathway. The β-Catenin phosphorylation level decreased when Atg5 was blocked. Atg5 cooperated with β-Catenin to modulate cortical NPCs differentiation and proliferation. Our results revealed that Atg5 has a crucial role in cortical neurogenesis during early embryonic brain development, which may contribute to the understanding of neurodevelopmental disorders caused by autophagy dysregulation.

Show MeSH
Related in: MedlinePlus