Abstract
Adipose tissue enlargement in obesity leads to hypoxia, which may promote premature aging. This study aimed to understand the hypoxic response in 3D cultures of SGBS cells, a model for brown-like adipose tissue expressing uncoupling protein 1 (UCP1). Single-nucleus RNA sequencing of SGBS organoids revealed a heterogeneous composition and sub-population-specific responses to hypoxia. The analysis identified a cluster of transcriptional repression, indicating dying cells, and implied a role of ferroptosis in this model. Further experiments with SGBS cells and white adipose tissue-derived stem/progenitor cells showed that Acyl-CoA synthetase long-chain family member 4 (ACSL4), a key enzyme in ferroptosis, is expressed only in the presence of browning factors. Hypoxia downregulated ACSL4 protein in SGBS organoids but induced an inflammaging phenotype. Analysis of brown-like epicardial adipose tissue from cardiac surgery patients revealed a significant positive correlation of ACSL4 mRNA with UCP1 and hypoxia-inducible pro-inflammatory markers, while ACSL4 protein appeared to be inversely correlated. In conclusion, this study demonstrates that adipocytes' capability to undergo ACSL4-mediated ferroptosis is linked to brown-like adipogenesis, suggesting an opportunity to modulate ferroptotic signaling in adipose tissue. The dual role of hypoxia by inhibiting ACSL4 but promoting inflammaging indicates a relationship between ferroptosis and aging that warrants further investigation.