Activation of nuclear factor-κB pathway is responsible for tumor necrosis factor-α-induced up-regulation of endothelin B2 receptor expression in vascular smooth muscle cells in vitro

The endothelin B2 (ETB2) receptors are induced in vascular smooth muscle cells (VSMCs) in cardiovascular diseases. We tested if in vitro short-term exposure to the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) could up-regulate ETB2 receptors in rat mesenteric arteries, and if this effect is through activation of intracellular nuclear factor-κB (NF-κB) pathway. The mesenteric arteries were dissected from male Sprague-Dawley rats and the endothelium was removed. The arteries were co-incubated with TNF-α in serum-free Dulbecco's modified Eagle's medium. Real-time reverse transcription-PCR, Western blot and immunohistochemical staining were employed to assess the mRNA/protein expression of ETB2 receptors and activation of NF-κB pathway. The results showed that, during organ culture, TNF-α concentration-dependently enhanced ETB2 receptors expression at both mRNA and protein levels, paralleled with activation of NF-κB pathway in VSMC. The up-regulated ETB2 receptor expression and NF-κB activation could be effectively suppressed by general transcriptional inhibitor actinomycin D, or either of the selective IκB kinase inhibitors wedelolactone and IMD-0354. Conclusively, the activation of intracellular NF-κB pathway is responsible for the up-regulation of ETB2 receptors induced by short-term exposure to TNF-α. This could partly explain the toxic effects of TNF-α on VSMCs that account for cardiovascular diseases.

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► We examined the mechanism of TNF-α on regulating ETB2 receptors during organ culture.
► TNF-α augmented ETB2 receptor expression and activated NF-κB pathway in VSMC.
► The inhibition of transcription or NF-κB abolished the ETB2 receptor up-regulation.
► NF-κB pathway is responsible for the ETB2 receptor up-regulation by TNF-α.