Loss of TET2 impairs endothelial angiogenesis via downregulating STAT3 target genes

Endothelial TET2 regulates the white adipose browning and metabolism via fatty acid oxidation in obesity

Obesity is a complex metabolic disorder, manifesting as excessive accumulation of body fat. Ten-Eleven Translocation-2 (TET2) has garnered significant attention in the context of obesity due to its crucial role in epigenetic regulation and metabolic homeostasis. In this study, we aimed to investigate the effect of endothelial TET2 on obesity and explore the potential mechanism. We generated endothelial cell-specific TET2 deficiency mice and investigated endothelial TET2 using transcriptomic and epigenomic analyses. We determined the downregulation of endothelial TET2 in white adipose tissues. Furthermore, we identified that endothelial TET2 loss aggravated high-fat diet-induced obesity by inhibiting vascularization and thus suppressing white adipose tissue browning. Mechanistically, endothelial TET2 modulates obesity by engaging in endothelial fatty acid oxidation and angiocrine-mediated secretion of bone morphogenetic protein 4 (BMP4), in which nuclear factor-erythroid 2-related factor 2 (NRF2) serves as a key mediator. Our study reveals that endothelial TET2 regulates white adipose tissue browning by interacting with NRF2 to facilitate fatty acid oxidation and lipolysis in adipocytes.

Hypoxia-induced P4HA1 overexpression promotes post-ischemic angiogenesis by enhancing endothelial glycolysis through downregulating FBP1

BACKGROUND

Angiogenesis is essential for tissue repair in ischemic diseases, relying on glycolysis as its primary energy source. Prolyl 4-hydroxylase subunit alpha 1 (P4HA1), the catalytic subunit of collagen prolyl 4-hydroxylase, is a glycolysis-related gene in cancers. However, its role in glycolysis-induced angiogenesis remains unclear.

METHODS

P4HA1 expression was modulated using adenoviruses. Endothelial angiogenesis was evaluated through 5-ethynyl-2'-deoxyuridine incorporation, transwell migration, and tube formation assays in vitro. In vivo experiments measured blood flow and capillary density in the hindlimb ischemia (HLI) model. Glycolytic stress assays, glucose uptake, lactate production, and quantitative reverse transcription-polymerase chain reaction (RT-PCR) were employed to assess glycolytic capacity. Transcriptome sequencing, validated by western blotting and RT-PCR, was utilized to determine underlying mechanisms.

RESULTS

P4HA1 was upregulated in endothelial cells under hypoxia and in the HLI model. P4HA1 overexpression promoted angiogenesis in vitro and in vivo, while its knockdown had the opposite effect. P4HA1 overexpression reduced cellular α-ketoglutarate (α-KG) levels by consuming α-KG during collagen hydroxylation. Downregulation of α-KG reduced the protein level of a DNA dioxygenase, ten-eleven translocation 2 (TET2), and its recruitment to the fructose-1,6-biphosphatase (FBP1) promoter, resulting in decreased FBP1 expression. The decrease in FBP1 enhanced glycolytic metabolism, thereby promoting endothelial angiogenesis.

CONCLUSIONS

Hypoxia-induced endothelial P4HA1 overexpression enhanced angiogenesis by promoting glycolytic metabolism reprogramming through the P4HA1/α-KG/TET2/FBP1 pathway. The study's findings underscore the significance of P4HA1 in post-ischemic angiogenesis, suggesting its therapeutic potential for post-ischemic tissue repair.