Connexin 43 regulates the barrier function of alveolar type Ⅱ epithelial cells in sepsis-induced acute lung injury through serine 373 mediated by protein kinase A

doi:10.3877/cma.j.issn.1674-6880.2021.05.002

Abstract

Abstract:

Objective

To observe the relationship between connexin 43 (Cx43) of alveolar type Ⅱ epithelial cells and the permeability of alveolar air blood barrier in sepsis-induced acute lung injury, and to explore the role of Cx43 and protein kinase A (PKA) signaling pathway in sepsis-induced acute lung injury.

Methods

A549 cells were divided into a control group, a sepsis group [lipopolysaccharide (LPS) group], a LPS + PKA inhibitor group (LPS + H89 group) and a 8-Bromo-cAMP group (PKA activator group). Both the LPS group and LPS + H89 group were treated with LPS 1 μg/mL, while the PKA activator group was treated with 8-Bromo-cAMP 10 μmol/L, all for 24 h. In addition, the LPS + H89 group was pretreated with H89 10 μmol/L for 1 h. The protein expression levels of phosphorylated Cx43 (p-Cx43), PKA and phosphorylated PKA (p-PKA) in each group were determined by the Western-blotting assay. Monolayer cell cultures were performed with Transwell plates, and the permeability of A549 monolayers was determined by a microplate reader.

Results

The p-Cx43, PKA and p-PKA protein expression levels and the cell permeability were significantly different among the four groups (F = 8.961, 249.729, 7 526.430, 3 661.755; all P < 0.05). Further pairwise comparisons revealed that compared with the control group, the p-Cx43 and PKA protein expression levels and the cell permeability significantly increased in the LPS and PKA activator groups, and the p-PKA protein expression levels significantly increased in the LPS, LPS + H89 and PKA activator groups (all P < 0.05). The p-Cx43 and PKA protein expression levels and the cell permeability reduced, while the p-PKA protein expression levels increased in the LPS + H89 group compared with the LPS group (all P < 0.05). The cell permeability in the PKA activator group significantly increased compared with the LPS and LPS + H89 groups (both P < 0.05).

Conclusion

Cx43 plays a key role in sepsis-induced acute lung injury through regulating serine 373 mediated by PKA, which can increase permeability of alveolar type Ⅱ epithelial cells, disrupt alveolar barrier function and increase gap junction intercellular communication.

Key words: Sepsis, Acute lung injury, Protein kinase A, Connexin 43, Alveolar type Ⅱ epithelial cells

Xiwei Zhao, Jiawei Zhou, Kai Liu, Linyi Hou, Wenkai Zhang. Connexin 43 regulates the barrier function of alveolar type Ⅱ epithelial cells in sepsis-induced acute lung injury through serine 373 mediated by protein kinase A[J]. Chinese Journal of Critical Care Medicine(Electronic Edition), 2021, 14(05): 355-361.

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References 35

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