Exploring TβRI inhibitors from Arenaria kansuensis based on 3D-QSAR, molecular docking and molecular dynamics...

Pulmonary fibrosis (PF) is a kind of interstitial lung disease that seriously threatens human life and health. Up to now, there is no specifically therapeutic drug. Arenaria kansuensis, a typical Tibetan medicine, has been previously proved to have anti-PF pharmacological activity by our group. However, the specific target and molecular mechanism of pharmacological active ingredients from it are still unknown.

This study aimed to explore the molecular mechanism and specific target of pharmacological active ingredients from A. kansuensis for treating PF.

Virtual screening including 3D-QSAR, molecular docking and molecular dynamics simulation were used to screen TβRI inhibitor. CETSA experiment was used to verify the interaction between GAK (a β-carboline alkaloid isolated from A. kansuensis) and TβRI. Cell and molecular experiments including observation of cell morphology and Western blot were applied to investigate the molecular mechanism of action of GAK for treating PF. Animal experiments including physiological index, immunohistochemistry and ELISA were used to comprehensively evaluate the anti-PF effect of GAK and explore the corresponding mechanism of action.

Results of 3D-QSAR experiment indicated that GAK is a much stronger potential TβRI inhibitor, molecular mechanism study showed that 30 μM GAK could significantly keep TβRI more stable which indicated that the direct binding interaction between GAK and TβRI, it targetedly inhibited TβRI through forming hydrogen bonds with LYS232, SER280 and ASP351 and the binding energies is -56.05 kcal/mol. In vitro experiment showed GAK could suppress downstream signal pathways of TβRI including MAPK, PI3K/AKT and NF-κB pathways during EMT process. In vivo experiment showed that GAK could improve the survival rate and body weight of PF mice, alleviate the symptoms of histopathological severity, inflammatory cell infiltration and collagen deposition in lung tissue of PF mice through inhibiting EMT process of PF.

This work not only provided evidence to support GAK as a novel TβRI inhibitor for treating PF through multiple pathways, but also reveal the specific target and molecular mechanism of β-carboline alkaloids from A. kansuensis for treating PF.