Limits...
Nucleotide synthesis is regulated by cytoophidium formation during neurodevelopment and adaptive metabolism.

Aughey GN, Grice SJ, Shen QJ, Xu Y, Chang CC, Azzam G, Wang PY, Freeman-Mills L, Pai LM, Sung LY, Yan J, Liu JL - Biol Open (2014)

Bottom Line: Furthermore, our global metabolic profiling demonstrates that CTPsyn overexpression does not significantly alter CTPsyn-related enzymatic activity, suggesting that cytoophidium formation facilitates metabolic stabilisation.In addition, we show that overexpression of CTPsyn only results in moderate increase of CTP pool in human stable cell lines.Together, our study provides experimental evidence, and a mathematical model, for the hypothesis that inactive CTPsyn is incorporated into cytoophidia.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom.

No MeSH data available.


AKT1 knockdown induces Cytoophida formation.(A) When nutrients are available insulin-like peptides (ILPs) bind the insulin receptor (InR), activating the PI3K/AKT pathway. This in turn inhibits the growth inhibitor Foxo and activates TOR, leading to growth and division of cells, including neuroblasts. (B) AKT1 was knocked down in neuroblasts using Insc-GAL4, UAS-AKT1-RNAi to mimic nutritional stress. AKT1 knockdown induces cytophidia formation. (C) Insc-GAL4 controls displayed very few neuroblasts with cytophidia. (D) Cytophidia in Insc-GAL4, UAS-AKT1-RNAi neuroblasts. These images are representative of >6 animals imaged. Scale bars: 10 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4232762&req=5

f04: AKT1 knockdown induces Cytoophida formation.(A) When nutrients are available insulin-like peptides (ILPs) bind the insulin receptor (InR), activating the PI3K/AKT pathway. This in turn inhibits the growth inhibitor Foxo and activates TOR, leading to growth and division of cells, including neuroblasts. (B) AKT1 was knocked down in neuroblasts using Insc-GAL4, UAS-AKT1-RNAi to mimic nutritional stress. AKT1 knockdown induces cytophidia formation. (C) Insc-GAL4 controls displayed very few neuroblasts with cytophidia. (D) Cytophidia in Insc-GAL4, UAS-AKT1-RNAi neuroblasts. These images are representative of >6 animals imaged. Scale bars: 10 µm.

Mentions: To mimic nutritional stress, we also knocked-down the serine-threonine kinase AKT1 in neuroblasts using Insc-GAL4, UAS-AKT1-RNAi. During L1 and L2, normal food intake activates insulin signalling and the PI3K/AKT pathway. This in turn activates TOR, and represses the growth inhibitor Foxo, leading to the initiation of neuroblast division and cell proliferation (Fig. 4A) (Chell and Brand, 2010; Goberdhan and Wilson, 2003; Sousa-Nunes et al., 2011). Insc-GAL4, UAS-AKT1-RNAi neuroblasts have increased numbers of cytoophidia when compared to controls (Fig. 4B–D), suggesting that inactivation of the AKT1 pathway induces cytoophidia formation. The prolonged presence of cytoophidia in the neuroblast however, appears to have no detrimental effect. Overexpression of CTPsyn in the neuroblasts (Pros-GAL4, UAS-CTPsyn-A) generates extremely large cytoophidia, but this has no overt effect on overall development (supplementary material Fig. S1). In summary, cytoophidia are formed in neuroblasts that are quiescent, or in neuroblasts from the CNS of starved and developmentally stalled larvae. These results are consistent with the hypothesis that CTPsyn in cytoophidia is inactive.


Nucleotide synthesis is regulated by cytoophidium formation during neurodevelopment and adaptive metabolism.

Aughey GN, Grice SJ, Shen QJ, Xu Y, Chang CC, Azzam G, Wang PY, Freeman-Mills L, Pai LM, Sung LY, Yan J, Liu JL - Biol Open (2014)

AKT1 knockdown induces Cytoophida formation.(A) When nutrients are available insulin-like peptides (ILPs) bind the insulin receptor (InR), activating the PI3K/AKT pathway. This in turn inhibits the growth inhibitor Foxo and activates TOR, leading to growth and division of cells, including neuroblasts. (B) AKT1 was knocked down in neuroblasts using Insc-GAL4, UAS-AKT1-RNAi to mimic nutritional stress. AKT1 knockdown induces cytophidia formation. (C) Insc-GAL4 controls displayed very few neuroblasts with cytophidia. (D) Cytophidia in Insc-GAL4, UAS-AKT1-RNAi neuroblasts. These images are representative of >6 animals imaged. Scale bars: 10 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232762&req=5

f04: AKT1 knockdown induces Cytoophida formation.(A) When nutrients are available insulin-like peptides (ILPs) bind the insulin receptor (InR), activating the PI3K/AKT pathway. This in turn inhibits the growth inhibitor Foxo and activates TOR, leading to growth and division of cells, including neuroblasts. (B) AKT1 was knocked down in neuroblasts using Insc-GAL4, UAS-AKT1-RNAi to mimic nutritional stress. AKT1 knockdown induces cytophidia formation. (C) Insc-GAL4 controls displayed very few neuroblasts with cytophidia. (D) Cytophidia in Insc-GAL4, UAS-AKT1-RNAi neuroblasts. These images are representative of >6 animals imaged. Scale bars: 10 µm.
Mentions: To mimic nutritional stress, we also knocked-down the serine-threonine kinase AKT1 in neuroblasts using Insc-GAL4, UAS-AKT1-RNAi. During L1 and L2, normal food intake activates insulin signalling and the PI3K/AKT pathway. This in turn activates TOR, and represses the growth inhibitor Foxo, leading to the initiation of neuroblast division and cell proliferation (Fig. 4A) (Chell and Brand, 2010; Goberdhan and Wilson, 2003; Sousa-Nunes et al., 2011). Insc-GAL4, UAS-AKT1-RNAi neuroblasts have increased numbers of cytoophidia when compared to controls (Fig. 4B–D), suggesting that inactivation of the AKT1 pathway induces cytoophidia formation. The prolonged presence of cytoophidia in the neuroblast however, appears to have no detrimental effect. Overexpression of CTPsyn in the neuroblasts (Pros-GAL4, UAS-CTPsyn-A) generates extremely large cytoophidia, but this has no overt effect on overall development (supplementary material Fig. S1). In summary, cytoophidia are formed in neuroblasts that are quiescent, or in neuroblasts from the CNS of starved and developmentally stalled larvae. These results are consistent with the hypothesis that CTPsyn in cytoophidia is inactive.

Bottom Line: Furthermore, our global metabolic profiling demonstrates that CTPsyn overexpression does not significantly alter CTPsyn-related enzymatic activity, suggesting that cytoophidium formation facilitates metabolic stabilisation.In addition, we show that overexpression of CTPsyn only results in moderate increase of CTP pool in human stable cell lines.Together, our study provides experimental evidence, and a mathematical model, for the hypothesis that inactive CTPsyn is incorporated into cytoophidia.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom.

No MeSH data available.