Extended Data Fig. 3: XBP1 inhibits glutamine influx in response to glucose deprivation.

a, b, Naive splenic CD4⁺ T cells isolated from wild-type mice were activated by CD3 and CD28 stimulation for 48 h and then incubated for 6 h in the indicated medium. a, Expression of gene markers related to ER stress (n = 4 from two independent experiments). Data are shown as per cent response change compared with control in the presence of medium containing glucose and glutamine. b, Maximal OCR was measured in CD4⁺ T cells in the presence or absence of glucose, and treated with corresponding medium (untreated, n = 5) or inhibitors blocking pyruvate (UK5099, n = 5), glutamine (BPTES, n = 4) or fatty acid (etomoxir, n = 4) oxidation. Data are presented as per cent response change compared with untreated control in the presence of glucose. c–i, Naive splenic CD4⁺ T cells isolated from wild-type (solid bars) or XBP1-deficient (hatched bars) mice were activated by CD3 and CD28 stimulation for 48 h, followed by culture in the presence or absence of glucose for 4.5 h, and then pulsed with [U-¹³C]glutamine for an additional 1.5 h in the same culture condition. Relative abundance of ¹³C-labelled metabolites and TCA intermediates including glutamine (c), glutamate (d), α-ketoglutarate (e), succinate (f), malate (g), citrate (h) and aspartate (i) was determined by LC–MS/MS. Data were normalized to cell number in all cases and are representative of two independent experiments with n = 2 biologically distinct samples per group. Data are shown as mean ± s.e.m. n values represent biologically independent samples (a, b). One-way ANOVA with Bonferroni’s multiple comparisons test (a); one-way ANOVA with Tukey’s multiple comparisons test (b); *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.

Source data