RESUMO
The histamine H(1) receptor (H1R) gene is up-regulated in patients with allergic rhinitis. However, the mechanism and reason underlying this up-regulation are still unknown. Recently, we reported that the H1R expression level is strongly correlated with the severity of allergic symptoms. Therefore, understanding the mechanism of this up-regulation will help to develop new anti-allergic drugs targeted for H1R gene expression. Here we studied the molecular mechanism of H1R up-regulation in HeLa cells that express H1R endogenously in response to histamine and phorbol 12-myristate 13-acetate (PMA). In HeLa cells, histamine stimulation caused up-regulation of H1R gene expression. Rottlerin, a PKCδ-selective inhibitor, inhibited up-regulation of H1R gene expression, but Go6976, an inhibitor of Ca(2+)-dependent PKCs, did not. Histamine or PMA stimulation resulted in PKCδ phosphorylation at Tyr(311) and Thr(505). Activation of PKCδ by H(2)O(2) resulted in H1R mRNA up-regulation. Overexpression of PKCδ enhanced up-regulation of H1R gene expression, and knockdown of the PKCδ gene suppressed this up-regulation. Histamine or PMA caused translocation PKCδ from the cytosol to the Golgi. U0126, an MEK inhibitor, and DPQ, a poly(ADP-ribose) polymerase-1 inhibitor, suppressed PMA-induced up-regulation of H1R gene expression. These results were confirmed by a luciferase assay using the H1R promoter. Phosphorylation of ERK and Raf-1 in response to PMA was also observed. However, real-time PCR analysis showed no inhibition of H1R mRNA up-regulation by a Raf-1 inhibitor. These results suggest the involvement of the PKCδ/ERK/poly(ADP-ribose) polymerase-1 signaling pathway in histamine- or PMA-induced up-regulation of H1R gene expression in HeLa cells.
