Journal: bioRxiv

Article Title: Nuclear α 1A -Adrenergic Receptor Regulation of cAMP Production by an Inside-Out MAP Kinase Signaling Pathway in Cardiac Myocytes

doi: 10.1101/2025.11.20.687712

Figure Lengend Snippet: Inside-out signaling pathway responsible for α 1 AR inhibition of βAR cAMP production. α 1A ARs in the nucleus inhibit cAMP production by βARs found at the plasma membrane by acting through a mitogen activated protein (MAP) kinase signaling pathway involving protein kinase C (PKC), Raf, and MEK. MEK activates ERK through a tyrosine kinase-dependent mechanism, and ERK can block βAR production of cAMP by activating arrestin, which depends on G protein kinase (GRK) phosphorylation of βARs. Activation of intracellular α 1A ARs by norepinephrine (NE) and methoxamine (METH) requires uptake of these agonists by the organic cation transporter OCT3. Inhibiting each step in this pathway with the compounds indicated can antagonize the effect of α-agonists on βAR production of cAMP (see text for details). Created in BioRender. Harvey, R. (2025) https://BioRender.com/ksom4md

Article Snippet: G-protein receptor kinase inhibitor (CMPD101), pan PKC inhibitor (Gö 69683), forskolin (FSK), methoxamine (METH), corticosterone (CORT), prazosin (PRAZ), Raf inhibitor (SB 590885), MEK inhibitor (U0126), and norepinephrine (NE) were purchased from Tocris Bioscience (Bristol, UK).

Techniques: Inhibition, Clinical Proteomics, Membrane, Blocking Assay, Phospho-proteomics, Activation Assay

Journal: bioRxiv

Article Title: Nuclear α 1A -Adrenergic Receptor Regulation of cAMP Production by an Inside-Out MAP Kinase Signaling Pathway in Cardiac Myocytes

doi: 10.1101/2025.11.20.687712

Figure Lengend Snippet: α 1A AR inhibition of cAMP production involves mitogen activated protein kinase kinase (MEK) and tyrosine kinase activity. Time course of changes in cAMP activity detected by the Epac2-camps biosensor produced by exposure to isoproterenol (ISO, 10 nM) followed by subsequent addition methoxamine (METH, 3 μM) in the presence of the MEK inhibitor U0126 (10 μM) (A) and the tyrosine kinase inhibitor lavendustin A (LAV A) (C) . FRET responses (ΔR/R 0 ) were normalized to the magnitude of the maximum cAMP response (MAX) observed upon exposure to ISO (1 μM) + IBMX (100 μM) in the same cell. The average response to ISO (10 nM) was not significantly affected by the addition of METH (3 μM) in cells treated with U0126 (n/N = 11/4, p = 0.99) (B) or in cells treated with LAV A (n/N = 12/3, p = 0.70) (D) (paired t-tests).

Article Snippet: G-protein receptor kinase inhibitor (CMPD101), pan PKC inhibitor (Gö 69683), forskolin (FSK), methoxamine (METH), corticosterone (CORT), prazosin (PRAZ), Raf inhibitor (SB 590885), MEK inhibitor (U0126), and norepinephrine (NE) were purchased from Tocris Bioscience (Bristol, UK).

Techniques: Inhibition, Activity Assay, Produced