Extracellular signal-regulated kinase 1/2-mediated transcriptional regulation of G-protein-coupled receptor kinase 3 expression in neuronal cells

S Salim, KM Standifer, DC Eikenburg - Journal of Pharmacology and …, 2007 - ASPET
Journal of Pharmacology and Experimental Therapeutics, 2007ASPET
Relatively small changes in G-protein-coupled receptor kinase (GRK) 3 expression (∼ 2-
fold) profoundly affect α2-adrenergic receptor (AR) function and preferentially regulate
neuronal α2A-and α2B-AR signaling. In the present study, we provide evidence that
epinephrine (EPI)-induced up-regulation of GRK3 protein expression in two neuronal cell
lines, BE (2)-C cells (endogenously express α2A-and β2-AR) and BN17 cells [endogenously
express α2B (NG108) and transfected to express β2-AR] is due in part to increased GRK3 …
Relatively small changes in G-protein-coupled receptor kinase (GRK) 3 expression (∼2-fold) profoundly affect α2-adrenergic receptor (AR) function and preferentially regulate neuronal α2A- and α2B-AR signaling. In the present study, we provide evidence that epinephrine (EPI)-induced up-regulation of GRK3 protein expression in two neuronal cell lines, BE(2)-C cells (endogenously express α2A- and β2-AR) and BN17 cells [endogenously express α2B (NG108) and transfected to express β2-AR] is due in part to increased GRK3 gene expression. In both cell lines, the increase in GRK3 transcription occurred via an extracellular signal-regulated kinase (ERK) 1/2-dependent mechanism because the increase in GRK3 mRNA is eliminated in the presence of the mitogen-activated protein kinase/ERK kinase 1/2 inhibitor, U0126 [1,4-diamino-2,3-dicyano-1,4-bis (2-amino phenylthiobutadiene)]. EPI-induced GRK3 mRNA up-regulation also is prevented in the presence of propranolol or phentolamine. Moreover, GRK3 mRNA did not increase in response to EPI treatment in NG108 cells (endogenously express α2B-AR with no β2-AR). Both these results suggest that simultaneous activation of α2- and β2-AR by EPI is required for the ERK1/2-dependent increase in GRK3 mRNA. The EPI-induced increase in GRK3 mRNA was unaffected in the presence of the protein kinase C inhibitor, chelerythrine chloride. Finally, EPI treatment resulted in increased nuclear translocation and accumulation of the transcription factors, Sp-1 and Ap-2, in BE(2)-C cells. Taken together, our results demonstrate the involvement of the ERK1/2 pathway in selective up-regulation of GRK3 mRNA expression, possibly via activation of Sp-1 and Ap-2 transcription factors in neuronal cells.
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