TNF‐α inhibits UCP‐1 expression in brown adipocytes via ERKs

Abstract
Tumor necrosis factor-α (TNF-α) activates extracellular-regulated kinases (ERKs) and p38 mitogen-activated protein kinase (p38MAPK), and inhibits the expression of uncoupling protein-1 (UCP-1) and adipocyte-specific genes in rat fetal brown adipocytes. MEK inhibition with PD98059 abolished the inhibitory effect of TNF-α on UCP-1, but not on adipogenic genes. In contrast, inhibition of p38MAPK with SB203580 potentiated the negative effect of TNF-α on UCP-1 and adipogenic genes. The inhibitory action of TNF-α was partially correlated with changes in C/EBPα and β protein levels and in their DNA binding activity, suggesting a role for these transcription factors. However, other transcription factors might explain the different regulation of UCP-1 and adipogenic genes by ERKs.