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.


Related in: MedlinePlus

CTPsyn distribution in Drosophila larval post embryonic neuroblasts (pNbs).(A) A schematic of the larval CNS showing the location of the pNbs. The box represents the section of the CNS represented in panels C and D. The majority of larval pNbs exit quiescence during the late L1 (1st instar) and early L2 (2nd instar) stages. This is characterised by pNb enlargement and the expression of markers such as Miranda (Mir). (B) Counts of pNbs containing cytoophidia in L2 early, L2 late and L3 larvae early reared under different feeding conditions (ND, normal diet; FR, food removed). n>10 animals per group. (C) CTPsyn localisation in early and late L2 when on a normal diet (see Materials and Methods). CTPsyn forms cytoophidia in quiescent pNbs (Mir negative). (D) As neuroblasts exit quiescence (late L2, normal diet) and begin to divide CTPsyn becomes diffuse. (E) CTPsyn localisation in late L2 when food is removed (late L2, food removed) after 24 hrs. CTPsyn aggregates into filaments when nutritional stresses are present. These images are representative of all 10 animals imaged. Scale bars: 10 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f02: CTPsyn distribution in Drosophila larval post embryonic neuroblasts (pNbs).(A) A schematic of the larval CNS showing the location of the pNbs. The box represents the section of the CNS represented in panels C and D. The majority of larval pNbs exit quiescence during the late L1 (1st instar) and early L2 (2nd instar) stages. This is characterised by pNb enlargement and the expression of markers such as Miranda (Mir). (B) Counts of pNbs containing cytoophidia in L2 early, L2 late and L3 larvae early reared under different feeding conditions (ND, normal diet; FR, food removed). n>10 animals per group. (C) CTPsyn localisation in early and late L2 when on a normal diet (see Materials and Methods). CTPsyn forms cytoophidia in quiescent pNbs (Mir negative). (D) As neuroblasts exit quiescence (late L2, normal diet) and begin to divide CTPsyn becomes diffuse. (E) CTPsyn localisation in late L2 when food is removed (late L2, food removed) after 24 hrs. CTPsyn aggregates into filaments when nutritional stresses are present. These images are representative of all 10 animals imaged. Scale bars: 10 µm.

Mentions: Having seen that cytoophidium formation was responsive to nutrient stress in vivo we asked whether cytoophidium formation may be required during normal developmental processes. The post embryonic neuroblasts of the Drosophila CNS have previously been shown to exhibit high levels of cytoplasmic (i.e. non-filamentous) CTPsyn (Chen et al., 2011). The majority of these neuroblasts remain in a quiescent state during the early 1st instar larval stage (Fig. 2A). When the larvae have the required access to food, neuroblasts exit quiescence and re-enter the cell cycle during late 1st (L1) and early 2nd instar (L2) stages (Chell and Brand, 2010; Sousa-Nunes et al., 2011; Truman and Bate, 1988). As the demand for nucleotides is upregulated in proliferating cells, we hypothesised that there may be a concomitant switch in cytoophidium assembly/disassembly. We dissected 1st and 2nd instar larvae and investigated CTPsyn distribution by immunofluorescence. In well fed larvae, CTPsyn can be observed in filaments in the early 3rd instar thoracic ganglion, however these filaments disappear as larvae develop through L2 and L3 stages (Fig. 2A,B). The cytoophidia appear on the ventral surface in cells corresponding to the regions where the quiescent neuroblasts reside (Fig. 2C). As neuroblasts exit quiescence they enlarge and begin to divide. Following this process CTPsyn filaments disappear, and CTPsyn is localised in the cytoplasm in a diffuse pattern (Fig. 2D).


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)

CTPsyn distribution in Drosophila larval post embryonic neuroblasts (pNbs).(A) A schematic of the larval CNS showing the location of the pNbs. The box represents the section of the CNS represented in panels C and D. The majority of larval pNbs exit quiescence during the late L1 (1st instar) and early L2 (2nd instar) stages. This is characterised by pNb enlargement and the expression of markers such as Miranda (Mir). (B) Counts of pNbs containing cytoophidia in L2 early, L2 late and L3 larvae early reared under different feeding conditions (ND, normal diet; FR, food removed). n>10 animals per group. (C) CTPsyn localisation in early and late L2 when on a normal diet (see Materials and Methods). CTPsyn forms cytoophidia in quiescent pNbs (Mir negative). (D) As neuroblasts exit quiescence (late L2, normal diet) and begin to divide CTPsyn becomes diffuse. (E) CTPsyn localisation in late L2 when food is removed (late L2, food removed) after 24 hrs. CTPsyn aggregates into filaments when nutritional stresses are present. These images are representative of all 10 animals imaged. Scale bars: 10 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f02: CTPsyn distribution in Drosophila larval post embryonic neuroblasts (pNbs).(A) A schematic of the larval CNS showing the location of the pNbs. The box represents the section of the CNS represented in panels C and D. The majority of larval pNbs exit quiescence during the late L1 (1st instar) and early L2 (2nd instar) stages. This is characterised by pNb enlargement and the expression of markers such as Miranda (Mir). (B) Counts of pNbs containing cytoophidia in L2 early, L2 late and L3 larvae early reared under different feeding conditions (ND, normal diet; FR, food removed). n>10 animals per group. (C) CTPsyn localisation in early and late L2 when on a normal diet (see Materials and Methods). CTPsyn forms cytoophidia in quiescent pNbs (Mir negative). (D) As neuroblasts exit quiescence (late L2, normal diet) and begin to divide CTPsyn becomes diffuse. (E) CTPsyn localisation in late L2 when food is removed (late L2, food removed) after 24 hrs. CTPsyn aggregates into filaments when nutritional stresses are present. These images are representative of all 10 animals imaged. Scale bars: 10 µm.
Mentions: Having seen that cytoophidium formation was responsive to nutrient stress in vivo we asked whether cytoophidium formation may be required during normal developmental processes. The post embryonic neuroblasts of the Drosophila CNS have previously been shown to exhibit high levels of cytoplasmic (i.e. non-filamentous) CTPsyn (Chen et al., 2011). The majority of these neuroblasts remain in a quiescent state during the early 1st instar larval stage (Fig. 2A). When the larvae have the required access to food, neuroblasts exit quiescence and re-enter the cell cycle during late 1st (L1) and early 2nd instar (L2) stages (Chell and Brand, 2010; Sousa-Nunes et al., 2011; Truman and Bate, 1988). As the demand for nucleotides is upregulated in proliferating cells, we hypothesised that there may be a concomitant switch in cytoophidium assembly/disassembly. We dissected 1st and 2nd instar larvae and investigated CTPsyn distribution by immunofluorescence. In well fed larvae, CTPsyn can be observed in filaments in the early 3rd instar thoracic ganglion, however these filaments disappear as larvae develop through L2 and L3 stages (Fig. 2A,B). The cytoophidia appear on the ventral surface in cells corresponding to the regions where the quiescent neuroblasts reside (Fig. 2C). As neuroblasts exit quiescence they enlarge and begin to divide. Following this process CTPsyn filaments disappear, and CTPsyn is localised in the cytoplasm in a diffuse pattern (Fig. 2D).

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.


Related in: MedlinePlus