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Updated: Apr 16, 2026

Inducing Acute Lung Injury in Mice by Direct Intratracheal Lipopolysaccharide Instillation
Published on: July 6, 2019
P38/MAPK contributes to endothelial barrier dysfunction via MAP4 phosphorylation-dependent microtubule disassembly in
Lingfei Li1, Jiongyu Hu2, Ting He1
1Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, Third Military Medical University, Chongqing, China.
Abstract:
Excessive activation of inflammation and the accompanying lung vascular endothelial barrier disruption are primary pathogenic features of acute lung injury (ALI). Microtubule-associated protein 4 (MAP4), a tubulin assembly-promoting protein, is important for maintaining the microtubule (MT) cytoskeleton and cell-cell junctional structures. However, both the involvement and exact mechanism of MAP4 in the development of endothelial barrier disruption in ALI remains unknown. In this study, lipopolysaccharide (LPS) and tumour necrosis factor-α (TNF-α) were applied to human pulmonary microvascular endothelial cells (HPMECs) to mimic the endothelial damage during inflammation in vitro. We demonstrated that the MAP4 (Ser696 and Ser787) phosphorylation increased concomitantly with the p38/MAPK pathway activation by the LPS and TNF-α stimulation of HPMECs, which induced MT disassembly followed by hyperpermeability. Moreover, the application of taxol, the overexpression of a MAP4 (Ala) mutant, or the application of the p38/MAPK inhibitor SB203580 inhibited the MT disruption and the intracellular junction dysfunction. In contrast, MKK6 (Glu), which constitutively activated p38/MAPK, resulted in microtubule depolymerisation and, subsequently, hyperpermeability. Our findings reveal a novel role of MAP4 in endothelial barrier dysfunction.
Insights
Microtubule-associated protein 4 (MAP4) plays a key role in acute lung injury (ALI) by disrupting endothelial cell junctions. Inhibiting p38/MAPK signaling protects against this MAP4-mediated damage.
Area of Science:
- Cell Biology
- Molecular Biology
- Pathology
Background:
- Acute lung injury (ALI) involves inflammation and disruption of the lung vascular endothelial barrier.
- Microtubule-associated protein 4 (MAP4) stabilizes microtubules and cell junctions, but its role in ALI is unclear.
Purpose of the Study:
- To investigate the mechanism of MAP4 in endothelial barrier disruption during ALI.
- To identify therapeutic targets for ALI.
Main Methods:
- Human pulmonary microvascular endothelial cells (HPMECs) were stimulated with lipopolysaccharide (LPS) and tumor necrosis factor-α (TNF-α).
- MAP4 phosphorylation, p38/MAPK pathway activation, microtubule stability, and cell permeability were assessed.
- Pharmacological inhibitors and genetic manipulation were used to explore the role of MAP4 and p38/MAPK.
Main Results:
- LPS and TNF-α induced MAP4 phosphorylation (at Ser696 and Ser787) and p38/MAPK activation in HPMECs.
- This led to microtubule disassembly and increased endothelial permeability.
- Taxol, MAP4 (Ala) mutant overexpression, and p38/MAPK inhibition (SB203580) prevented microtubule disruption and barrier dysfunction.
- MKK6 (Glu) constitutively activated p38/MAPK, causing microtubule depolymerization and hyperpermeability.
Conclusions:
- MAP4 phosphorylation, mediated by p38/MAPK activation, contributes to endothelial barrier dysfunction in ALI.
- Targeting the p38/MAPK pathway or MAP4 may offer a therapeutic strategy for ALI.
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Chronic Obstructive Pulmonary Disease-II: Pathophysiology
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