title: Loss of RBF1 changes glutamine catabolism.
abstract: Inactivation of the retinoblastoma tumor suppressor (pRB) alters the expression of a myriad of genes. To understand the altered cellular environment that these changes create, we took advantage of the Drosophila model system and used targeted liquid chromatography tandem mass spectrometry (LC-MS/MS) to profile the metabolic changes that occur when RBF1, the fly ortholog of pRB, is removed. We show that RBF1-depleted tissues and larvae are sensitive to fasting. Depletion of RBF1 causes major changes in nucleotide synthesis and glutathione metabolism. Under fasting conditions, these changes interconnect, and the increased replication demand of RBF1-depleted larvae is associated with the depletion of glutathione pools. In vivo (13)C isotopic tracer analysis shows that RBF1-depleted larvae increase the flux of glutamine toward glutathione synthesis, presumably to minimize oxidative stress. Concordantly, H(2)O(2) preferentially promoted apoptosis in RBF1-depleted tissues, and the sensitivity of RBF1-depleted animals to fasting was specifically suppressed by either a glutamine supplement or the antioxidant N-acetyl-cysteine. Effects of pRB activation/inactivation on glutamine catabolism were also detected in human cell lines. These results show that the inactivation of RB proteins causes metabolic reprogramming and that these consequences of RBF/RB function are present in both flies and human cell lines.
authors: Laboratory of Molecular Oncology, Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA. bnicolay@partners.org
authors: Brandon N
authors: BN
authors: Nicolay
authors: Paulo A
authors: PA
authors: Gameiro
authors: Katrin
authors: K
authors: Tschöp
authors: Michael
authors: M
authors: Korenjak
authors: Andreas M
authors: AM
authors: Heilmann
authors: John M
authors: JM
authors: Asara
authors: Gregory
authors: G
authors: Stephanopoulos
authors: Othon
authors: O
authors: Iliopoulos
authors: Nicholas J
authors: NJ
authors: Dyson
mesh_terms: D000818:Animals; D017209:Apoptosis; D045744:Cell Line, Tumor; D004249:DNA Damage; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism*; D005215:Fasting / Q000378:metabolism; D005973:Glutamine / Q000096:biosynthesis*; D005978:Glutathione / Q000096:biosynthesis; D006801:Humans; D007814:Larva; D009154:Mutation; D009711:Nucleotides / Q000096:biosynthesis; D018384:Oxidative Stress; D016160:Retinoblastoma Protein; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D009711:Nucleotides; C099965:Rbf protein, Drosophila; D016160:Retinoblastoma Protein; D014157:Transcription Factors; D005973:Glutamine; D005978:Glutathione