Fig. 3. ATF4 binds to the promoters of fructolytic genes to activate fructolysis upon glucose deprivation.

a U87 cells were treated without or with glucose deprivation for 18 h. Chromatin immunoprecipitation (ChIP) combined with high-throughput sequencing (ChIP-seq) was performed using the ATF4 antibody and the promoters of indicated genes were visualized using Integrated Genome Browser. This experiment was performed twice independently with similar results. b U87 cells were infected with luciferase-reporter lentiviruses carrying SLC2A5 (−593 to +255 bp) or ALDOB (−661 to +214 bp) promoter without or with disruption of the CARE motif. These cells were treated without or with glucose deprivation for 18 h. The firefly luciferase activity was normalized with the cell numbers obtained from the duplicated samples and presented as fold change induced by glucose deprivation. CARE, C/EBP-ATF response element. c–f U87 and LN229 cells without or with disruption of the CARE motifs located within the promoters of SLC2A5 or ALDOB were treated without or with glucose deprivation for 18 h. c, d Quantitative PCR (c) and immunoblotting with indicated antibodies (d) were performed. Data were normalized with β-actin mRNA levels and presented as fold change induced by glucose deprivation (c). e Indicated GBM cells were treated without or with glucose deprivation for 18 h. Fructose metabolic rate was measured by monitoring the conversion of D-[5-³H] fructose to ³H₂O and normalized to cell number. c.p.m, counts per minute. f Indicated GBM cells treated without or with glucose deprivation for 18 h were incubated with 10 mM of fructose for another 18 h. The media were collected for analysis of fructose consumption. WT, wild type; dSLC2A5-C1/2 and dALDOB-C1/2, cell clone 1/2 with disruption of the CARE motifs located within the promoters of SLC2A5 and ALDOB, respectively (c–f). Data represent the mean ± SD of three (b, e, f) or four (c) independent experiments. The experiments were repeated three times independently with similar results (d). P values were determined by the two-tailed Student’s t-test (e, f). Source data are provided as a Source Data file.