PDK1/Akt/PDE4D axis identified as a target for asthma remedy synergistic with β2 AR agonists by a natural agent arctigenin.
BACKGROUND
Asthma is a heterogenetic disorder characterized by chronic inflammation with variable airflow obstruction and airway hyper-responsiveness. As the most potent and popular bronchodilators, β2 adrenergic receptor (β2 AR) agonists bind to the β2 ARs that are coupled via a stimulatory G protein to adenylyl cyclase, thereby improving cAMP accumulation and resulting in airway smooth muscle relaxation. We previously demonstrated arctigenin had a synergistic function with the β2 AR agonist, but the target for this remained elusive.


METHODS
Chemical proteomics capturing was used to enrich and uncover the target of arctigenin in human bronchial smooth muscle cells, and reverse docking and molecular dynamic stimulation were performed to evaluate the binding of arctigenin and its target. In vitro enzyme activities and protein levels were demonstrated with special kits and Western blotting. Finally, guinea pig tracheal muscle segregation and ex vivo function were analysed.


RESULTS
Arctigenin bound to PDK1 with an ideal binding free energy -25.45 kcal/mol and inhibited PDK1 kinase activity without changing its protein level. Additionally, arctigenin reduced PKB/Akt-induced phosphorylation of PDE4D, which was first identified in this study. Attenuation of PDE4D resulted in cAMP accumulation in human bronchial smooth muscle. The inhibition of PDK1 showed a synergistic function with β2 AR agonists and relaxed the constriction of segregated guinea pig tracheal muscle.


CONCLUSIONS
The PDK1/Akt/PDE4D axis serves as a novel asthma target, which may benefit airflow obstruction.
State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China.|State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, China.|State Key Laboratory of Medicinal Chemical Biology, Department of Biochemistry, College of Life Sciences, Nankai University, Tianjin, China.
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R
Fang
State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China.
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Q
Cui
State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China.
J
J
Sun
State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China.
X
X
Duan
State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China.
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X
Ma
State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China.
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W
Wang
State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China.
B
B
Cheng
State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China.
Y
Y
Liu
State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China.|State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, China.
Y
Y
Hou
State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China.
G
G
Bai
D064413:3-Phosphoinositide-Dependent Protein Kinases / Q000187:drug effects / Q000378:metabolism; D058666:Adrenergic beta-2 Receptor Agonists / Q000494:pharmacology; D000818:Animals; D018927:Anti-Asthmatic Agents / Q000494:pharmacology*; D001249:Asthma / Q000378:metabolism*; D015153:Blotting, Western; D001980:Bronchi / Q000187:drug effects* / Q000378:metabolism; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4 / Q000187:drug effects / Q000378:metabolism; D004357:Drug Synergism; D005663:Furans / Q000494:pharmacology*; D006168:Guinea Pigs; D006801:Humans; D017705:Lignans / Q000494:pharmacology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
D058666:Adrenergic beta-2 Receptor Agonists; D018927:Anti-Asthmatic Agents; D005663:Furans; D017705:Lignans; D064413:3-Phosphoinositide-Dependent Protein Kinases; C578562:PDPK1 protein, human; D051057:Proto-Oncogene Proteins c-akt; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; C517376:PDE4D protein, human; C071942:arctigenin
PDK1; PDK1/Akt/PDE4D axis; arctigenin; chemical proteomics; β2AR agonists