Project description:With the aim to identify new therapeutic targets for T-ALL treatment, we integrated transcriptomics and metabolomics data, including live-cell NMR-spectroscopy, of cell lines and patient samples. We found that T-ALL cells have limited energy availability, resulting in down-regulated mTOR-signalling and reduced autophagy. Despite this, mTOR kinase activity is essential for the glutamine-uptake and rapid proliferation. T-ALL cells use glutamine as a source for all nitrogen atoms in purines and for all but one carbon in pyrimidines. We show that EAAT1, the glutamate-aspartate transporter normally only expressed in the CNS, is a crucial facilitator of the glutamine conversion to nucleotides. T-ALL cell proliferation depends on EAAT1 function, identifying it as a target for T-ALL treatment.
Project description:The PI3K-PKB/c-akt-FOXO signalling network provides a major intracellular hub for regulation of cell proliferation, survival and stress resistance1. Here we report a novel function for FOXO transcription factors in regulating autophagy through modulation of intracellular glutamine levels. To identify novel transcriptional targets of this module we performed an unbiased microarray analysis after conditional activation of the key components PI3K, PKB, FOXO3 and FOXO4. Utilising this global pathway approach we identified glutamine synthetase (GS) as being transcriptionally regulated by PI3K-PKB-FOXO signalling. FOXO-mediated increase in GS expression specifically induced glutamine production independently of cell type, and this was evolutionary conserved. FOXO activation resulted in mTOR inhibition by preventing the translocation of mTOR to lysosomal membranes, which was dependent on GS activity. Increased GS activity resulted in increased autophagosome turnover as measured by LC3 lipidation, p62 degradation, and confocal imaging of LC3, p62, WIPI-1, ULK2 and Atg12. Inhibition of FOXO3-mediated autophagy resulted in increased apoptosis, suggesting that the induction of autophagy by FOXO3-mediated upregulation of GS is important for cellular survival. These findings reveal a novel signalling network that can directly modulate autophagy through regulation of glutamine metabolism. conditional activation of pkb and pi3k were followed in a timeseries. Each timepoint consists of 4 independent replicates, labeled with either cy3 or cy5 and put on array against time0.
Project description:The PI3K-PKB/c-akt-FOXO signalling network provides a major intracellular hub for regulation of cell proliferation, survival and stress resistance1. Here we report a novel function for FOXO transcription factors in regulating autophagy through modulation of intracellular glutamine levels. To identify novel transcriptional targets of this module we performed an unbiased microarray analysis after conditional activation of the key components PI3K, PKB, FOXO3 and FOXO4. Utilising this global pathway approach we identified glutamine synthetase (GS) as being transcriptionally regulated by PI3K-PKB-FOXO signalling. FOXO-mediated increase in GS expression specifically induced glutamine production independently of cell type, and this was evolutionary conserved. FOXO activation resulted in mTOR inhibition by preventing the translocation of mTOR to lysosomal membranes, which was dependent on GS activity. Increased GS activity resulted in increased autophagosome turnover as measured by LC3 lipidation, p62 degradation, and confocal imaging of LC3, p62, WIPI-1, ULK2 and Atg12. Inhibition of FOXO3-mediated autophagy resulted in increased apoptosis, suggesting that the induction of autophagy by FOXO3-mediated upregulation of GS is important for cellular survival. These findings reveal a novel signalling network that can directly modulate autophagy through regulation of glutamine metabolism. conditional activation of foxo3 and foxo4 were followed in a timeseries. Each timepoint consists of 4 independent replicates, labeled with either cy3 or cy5 and put on array against time0 as reference.
Project description:The PI3K-PKB/c-akt-FOXO signalling network provides a major intracellular hub for regulation of cell proliferation, survival and stress resistance1. Here we report a novel function for FOXO transcription factors in regulating autophagy through modulation of intracellular glutamine levels. To identify novel transcriptional targets of this module we performed an unbiased microarray analysis after conditional activation of the key components PI3K, PKB, FOXO3 and FOXO4. Utilising this global pathway approach we identified glutamine synthetase (GS) as being transcriptionally regulated by PI3K-PKB-FOXO signalling. FOXO-mediated increase in GS expression specifically induced glutamine production independently of cell type, and this was evolutionary conserved. FOXO activation resulted in mTOR inhibition by preventing the translocation of mTOR to lysosomal membranes, which was dependent on GS activity. Increased GS activity resulted in increased autophagosome turnover as measured by LC3 lipidation, p62 degradation, and confocal imaging of LC3, p62, WIPI-1, ULK2 and Atg12. Inhibition of FOXO3-mediated autophagy resulted in increased apoptosis, suggesting that the induction of autophagy by FOXO3-mediated upregulation of GS is important for cellular survival. These findings reveal a novel signalling network that can directly modulate autophagy through regulation of glutamine metabolism.
Project description:The PI3K-PKB/c-akt-FOXO signalling network provides a major intracellular hub for regulation of cell proliferation, survival and stress resistance1. Here we report a novel function for FOXO transcription factors in regulating autophagy through modulation of intracellular glutamine levels. To identify novel transcriptional targets of this module we performed an unbiased microarray analysis after conditional activation of the key components PI3K, PKB, FOXO3 and FOXO4. Utilising this global pathway approach we identified glutamine synthetase (GS) as being transcriptionally regulated by PI3K-PKB-FOXO signalling. FOXO-mediated increase in GS expression specifically induced glutamine production independently of cell type, and this was evolutionary conserved. FOXO activation resulted in mTOR inhibition by preventing the translocation of mTOR to lysosomal membranes, which was dependent on GS activity. Increased GS activity resulted in increased autophagosome turnover as measured by LC3 lipidation, p62 degradation, and confocal imaging of LC3, p62, WIPI-1, ULK2 and Atg12. Inhibition of FOXO3-mediated autophagy resulted in increased apoptosis, suggesting that the induction of autophagy by FOXO3-mediated upregulation of GS is important for cellular survival. These findings reveal a novel signalling network that can directly modulate autophagy through regulation of glutamine metabolism.
Project description:STAT3 (Signal transducer and activator of transcription 3) expression is associated with with t(12;21) acute lymphoblastic leukaemia (ALL) and it is crucial for the survival of the t(12;21) ALL . Our study investigated the STAT3 regulated pathways and discovered a novel STAT3-TP53 axis in B-ALL. In order to determine the STAT3 regulated pathways in t(12;21) ALL cells, we performed RNAseq analysis on the Pre-B Acute Lymphoblastic Leukemia (ALL) cell line REH following shRNA-mediated STAT3 knockdown
Project description:Mosca2012 - Central Carbon Metabolism Regulated by AKT
The role of the PI3K/Akt/PKB signalling pathway in oncogenesis has been extensively investigated and altered expression or mutations of many components of this pathway have been implicated in human cancers. Indeed, expression of constitutively active forms of Akt/PKB can prevent cell death upon growth factor withdrawal. PI3K/Akt/mTOR-mediated survival relies on a profound metabolic adaptation, including aerobic glycolysis. Here, the link between the PI3K/Akt/mTOR pathway, glycolysis, lactic acid production and nucleotide biosynthesis has been modelled, considering two states - high and low PI3K/Akt/mTOR activity. The high PI3K/Akt/mTOR activity represents cancer cell line where PI3K/Akt/mTOR promotes a high rate of glucose metabolism (condition H) and the low PI3K/Akt/mTOR activity is characterised by a lower glycolytic rate due to a reduced PI3K/Akt/mTOR signal (condition L). This model corresponds to the high PI3K/Akt/mTOR signal (condition H).
This model is described in the article:
Computational Modelling of the Metabolic States Regulated by the Kinase Akt.
Mosca E, Alfieri R, Maj C, Bevilacqua A, Canti G, Milanesi L.
Frontiers in Systems Biology. 2012 Oct 13
Abstract:
Signal transduction pathways and gene regulation determine a major reorganization of metabolic activities in order to support cell proliferation. Protein Kinase B (PKB), also known as Akt, participates in the PI3K/Akt/mTOR pathway, a master regulator of aerobic glycolysis and cellular biosynthesis, two activities shown by both normal and cancer proliferating cells. Not surprisingly considering its relevance for cellular metabolism, Akt/PKB is often found hyperactive in cancer cells. In the last decade, many efforts have been made to improve the understanding of the control of glucose metabolism and the identification of a therapeutic window between proliferating cancer cells and proliferating normal cells. In this context, we have modelled the link between the PI3K/Akt/mTOR pathway, glycolysis, lactic acid production and nucleotide biosynthesis. We used a computational model in order to compare two metabolic states generated by the specific variation of the metabolic fluxes regulated by the activity of the PI3K/Akt/mTOR pathway. One of the two states represented the metabolism of a growing cancer cell characterised by aerobic glycolysis and cellular biosynthesis, while the other state represented the same metabolic network with a reduced glycolytic rate and a higher mitochondrial pyruvate metabolism, as reported in literature in relation to the activity of the PI3K/Akt/mTOR. Some steps that link glycolysis and pentose phosphate pathway revealed their importance for controlling the dynamics of cancer glucose metabolism.
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Project description:STAT3 (Signal transducer and activator of transcription 3) expression is associated with with t(12;21) acute lymphoblastic leukaemia (ALL) and it is crucial for the survival of the t(12;21) ALL . Our study investigated the STAT3 regulated pathways and discovered a novel STAT3-TP53 axis in B-ALL. In order to determine the STAT3 regulated pathways in t(12;21) ALL cells, we performed RNAseq analysis on the Pre-B Acute Lymphoblastic Leukemia (ALL) cell line REH, treated with DMSO vehicle control in comparison to 50uM S3I-021, a specific STAT3 inhibitor
Project description:The MondoA transcription factor forms a heterocomplex with its obligate partner Mlx to regulate ~75% of glucose-dependent transcription. By mediating glucose-induced activation of thioredoxin-interacting protein (TXNIP), MondoA directly represses glucose uptake. Given the predominant role of MondoA in controlling glucose-dependent transcription and glucose uptake, we asked whether glutamine regulates MondoA activity. Expression profiles from glucose and glutamine starved BxPC-3 cells (-G-Q) were compared with those from cells grown in glucose only (+G-Q), glutamine only (-G+Q) or glucose plus glutamine (+G+Q). As expected, TXNIP expression was highly induced by glucose. However, the addition of glutamine repressed the glucose-dependent induction of TXNIP. We show that glutamine inhibits MondoA-dependent transcriptional activation of TXNIP by triggering the recruitment of a histone deacetylase-dependent corepressor to the amino terminus of MondoA. Consistent with the repression of TXNIP, glucose uptake is elevated in cells grown in the presence of glucose and glutamine. Finally, alpha-ketoglutarate, a tricarboxylic acid cycle intermediate, also blocks MondoA-dependent activation of TXNIP and stimulates glucose uptake. Together, these results suggest that glutamine-dependent mitochondrial anapleurosis stimulates glucose uptake by restricting TXNIP expression via MondoA:Mlx complexes. Four growth conditons; four biological replicates
Project description:The MondoA transcription factor forms a heterocomplex with its obligate partner Mlx to regulate ~75% of glucose-dependent transcription. By mediating glucose-induced activation of thioredoxin-interacting protein (TXNIP), MondoA directly represses glucose uptake. Given the predominant role of MondoA in controlling glucose-dependent transcription and glucose uptake, we asked whether glutamine regulates MondoA activity. Expression profiles from glucose and glutamine starved BxPC-3 cells (-G-Q) were compared with those from cells grown in glucose only (+G-Q), glutamine only (-G+Q) or glucose plus glutamine (+G+Q). As expected, TXNIP expression was highly induced by glucose. However, the addition of glutamine repressed the glucose-dependent induction of TXNIP. We show that glutamine inhibits MondoA-dependent transcriptional activation of TXNIP by triggering the recruitment of a histone deacetylase-dependent corepressor to the amino terminus of MondoA. Consistent with the repression of TXNIP, glucose uptake is elevated in cells grown in the presence of glucose and glutamine. Finally, alpha-ketoglutarate, a tricarboxylic acid cycle intermediate, also blocks MondoA-dependent activation of TXNIP and stimulates glucose uptake. Together, these results suggest that glutamine-dependent mitochondrial anapleurosis stimulates glucose uptake by restricting TXNIP expression via MondoA:Mlx complexes.