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Updated: Mar 1, 2026
Kinase Inhibitor Screening In Self-assembled Human Protein Microarrays
Published on: October 23, 2019
Phenotypic screening identifies Axl kinase as a negative regulator of an alveolar epithelial cell phenotype
Naoya Fujino1, Hiroshi Kubo2, Rose A Maciewicz1
1Innovative Medicines and Early Development, Respiratory, Inflammation and Autoimmunity, AstraZeneca AB, Mölndal, Sweden.
Abstract:
Loss of epithelial barrier integrity is implicated in a number of human lung diseases. However, the molecular pathways underlying this process are poorly understood. In a phenotypic screen, we identified Axl kinase as a negative regulator of epithelial phenotype and function. Furthermore, suppression of Axl activity by a small molecule kinase inhibitor or downregulation of Axl expression by small interfering RNA led to: (1) the increase in epithelial surfactant protein expression; (2) a cell morphology transition from front-rear polarity to cuboidal shape; (3) the cytoskeletal re-organization resulting in decreased cell mobility; and (4) the acquisition of epithelial junctions. Loss of Axl activity reduced activation of the Axl canonical pathway members, Akt and extracellular signal-regulated kinase-1/2 and resulted in the loss of gene expression of a unique profile of epithelial-to-mesenchymal transition transcription factors including SNAI2, HOXA5, TBX2 or TBX3. Finally, we observed that Axl was activated in hyperplasia of epithelial cells in idiopathic pulmonary fibrosis where epithelial barrier integrity was lost. These results suggest that the Axl kinase signaling pathway is associated with the loss integrity of alveolar epithelium in pathological remodeling of human lung diseases.
Insights
Axl kinase inhibition restores epithelial barrier function in lung diseases by promoting cell junctions and reducing mobility. This pathway is activated in idiopathic pulmonary fibrosis, suggesting a therapeutic target.
Area of Science:
- Cell Biology
- Molecular Biology
- Pulmonary Medicine
Background:
- Epithelial barrier integrity is crucial for lung health but is compromised in various human lung diseases.
- The molecular mechanisms driving the loss of epithelial barrier function remain incompletely understood.
Purpose of the Study:
- To identify molecular regulators of epithelial barrier integrity using a phenotypic screen.
- To investigate the role of Axl kinase in epithelial cell function and its potential involvement in lung diseases.
Main Methods:
- Phenotypic screening to identify Axl kinase as a regulator of epithelial phenotype.
- Utilized small molecule kinase inhibitors and small interfering RNA to suppress Axl activity and expression.
- Assessed epithelial marker expression, cell morphology, cytoskeletal organization, and cell junctions.
- Analyzed canonical Axl pathway signaling (Akt, ERK1/2) and epithelial-to-mesenchymal transition (EMT) transcription factors.
- Examined Axl activation in lung tissue samples from idiopathic pulmonary fibrosis patients.
Main Results:
- Suppression of Axl kinase activity or expression enhanced epithelial surfactant protein expression, induced a cuboidal cell shape, reorganized the cytoskeleton to decrease cell mobility, and promoted epithelial junction formation.
- Loss of Axl activity reduced activation of Akt and ERK1/2 and downregulated key EMT transcription factors (SNAI2, HOXA5, TBX2, TBX3).
- Axl kinase was found to be activated in hyperplastic epithelial cells in idiopathic pulmonary fibrosis, a disease characterized by lost epithelial barrier integrity.
Conclusions:
- Axl kinase acts as a negative regulator of epithelial phenotype and function.
- The Axl kinase signaling pathway is implicated in the loss of alveolar epithelial integrity during pathological remodeling in human lung diseases.
- Targeting Axl kinase may represent a therapeutic strategy for restoring epithelial barrier function in lung diseases.
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