ABSTRACT: Th17 cell fate is shaped by cytokines, transcriptional regulators and metabolic cues, yet the contribution of extracellular guanine nucleotides to CD4⁺ T-cell polarization remains poorly defined. Here, we asked whether extracellular GDP acts as an instructive purine signal and whether RANBP1, a regulator of Ran-GTP hydrolysis and nucleo-cytoplasmic trafficking, mediates the GDP-dependent phenotype. In primary human CD4⁺ T and Th17 cells, we integrated Raman imaging, RNA-seq, proteomics, purine metabolomics, Seahorse bioenergetics, lactate assays, flow cytometry, western blotting and RANBP1 perturbation. GDP stimulation induced a coordinated nucleo-metabolic program rather than nonspecific activation. In CD4⁺ T cells, GDP remodeled nuclear biochemical composition, altered purine pools, enriched mitochondrial membrane and nucleotide-transporter pathways, and promoted a Th17-like signature marked by IL-23R, RORγt and IL-17A. Integrated RNA-seq/proteomic analysis revealed convergence on mitochondrial ATP/ADP transport, purine handling and immune differentiation, while western blotting showed modulation of PNP, LDHA and MCT1 together with lysine and histone-associated acetylation signals. In committed Th17 cells, GDP amplified central carbon metabolism, pyruvate-to-acetyl-CoA conversion, branched-chain amino acid degradation and DNA replication/repair, while reshaping inflammatory plasticity. RANBP1 overexpression faithfully reproduced key GDP-associated bioenergetic and Th17-like features, whereas RANBP1 silencing restrained metabolic fitness and allowed GDP to rescue a bioenergetic pattern reminiscent of GDP-treated naïve CD4⁺ cells. Exploratory pediatric B-ALL RNA-seq showed that purine, lactate/glucose, mitochondrial and nuclear-transport modules remained traceable during therapy. Together, purinergic signaling emerges as a microenvironmental and intracellular controller of T-cell fate. These findings position RANBP1 as a pivotal intracellular transducer linking extracellular GDP to metabolic rewiring and Th17-like polarization.
