BPGM shapes NFAT5-driven cellular responses

Abstract

Osmotic stress represents a major challenge to cells, particularly in the kidney, where tonicity gradients are both physiologically relevant and pathologically altered. The transcription factor nuclear factor of activated T cells 5 (NFAT5) is a key regulator of the osmoadaptive response, yet its downstream metabolic effectors remain incompletely understood. In this study, we identify the glycolytic side-branch enzyme 2,3-bisphosphoglycerate mutase (BPGM) as a transcriptional NFAT5 target that is induced under hypertonic conditions. RNA-seq analysis revealed that Bpgm knockdown significantly alters gene expression under osmotic stress (450 mOsmol/kg), with substantial overlap between BPGM- and NFAT5-responsive transcriptional programs. Bpgm depletion impairs the induction of canonical NFAT5 target genes, suggesting a functional interplay between metabolic and transcriptional adaptation. Promoter enrichment analysis showed that genes regulated by both NFAT5 and BPGM under hypertonic conditions are associated with CpG islands and GC-rich elements, supporting a link to chromatin structure and transcriptional accessibility. Consistently, we show that HIF-1α expression is regulated downstream of NFAT5 and BPGM, indicating a hierarchical organization of osmotic and hypoxic stress responses. We propose that BPGM facilitates NFAT5 function through metabolic-epigenetic coupling, acting as an amplifier of protective gene expression. Notably, this axis is active in BPGM-expressing cells such as those of the distal convoluted tubule. Thus, our findings establish BPGM as a critical node in the osmoadaptive gene regulatory network and highlight how cell type-specific metabolic profiles influence the transcriptional response to hypertonic stress.