Histamine H₁ Receptor-Mediated CREB Phosphorylation via G_q Protein Signaling and Arrestin Modulation

Area of Science:

• Pharmacology
• Molecular Biology
• Cell Signaling

Background:

• Histamine H1 receptors play key roles in physiological and pathophysiological processes, including inflammation and allergy.
• CREB (cAMP response element-binding protein) is a crucial transcription factor regulated by various signaling pathways.
• The precise intracellular signaling cascade linking H1 receptor activation to CREB phosphorylation remains incompletely understood.

Purpose of the Study:

• To elucidate the intracellular signaling pathway of H1 receptor-mediated CREB phosphorylation.
• To investigate the distinct roles of Gq proteins and arrestins in this signaling cascade.

Main Methods:

• Utilized Chinese hamster ovary (CHO) cells expressing wild-type (WT) human H1 receptors and C-terminal mutants (Gq-biased S487Trunc and arrestin-biased S487A).
• Assessed CREB and phosphorylated CREB expression via immunoblotting.
• Employed signaling pathway inhibitors (PKC, ERK, JNK) and Ca2+ chelators, alongside β-arrestin overexpression and knockdown (siRNA).

Main Results:

• Histamine induced CREB phosphorylation in WT and S487Trunc cells, but not in S487A cells.
• Inhibition of PKC, ERK, JNK, or Ca2+ attenuated histamine-induced CREB phosphorylation.
• β-arrestin overexpression increased basal CREB phosphorylation, while knockdown decreased it, demonstrating its modulatory role.

Conclusions:

• H1 receptor-mediated CREB phosphorylation is primarily driven by the Gq protein/Ca2+/PKC-dependent activation of ERK and JNK pathways.
• Arrestins play a modulatory role in this signaling pathway by influencing basal CREB phosphorylation levels.