Di-san junyi daxue xuebao (Apr 2020)

Effect of Brahma-related gene 1 knockout on number and function of type Ⅱ alveolar epithelial cells in mice

  • RUAN Lingying,
  • XUE Kunjiao,
  • XUE Kunjiao,
  • YING Linyan,
  • YING Linyan

DOI
https://doi.org/10.16016/j.1000-5404.201908160
Journal volume & issue
Vol. 42, no. 7
pp. 656 – 663

Abstract

Read online

Objective To investigate the effect of brahma-related gene 1 (Brg1) knockout on the number and function of type Ⅱ alveolar epithelial cells (AECⅡs) in C57BL/6 mice and explore the possible mechanisms. Methods Eight female wild-type (WT) C57BL/6 mice (6 to 8 weeks old) and 8 C57BL/6 mice with Brg1 gene knockout in type Ⅱ alveolar epithelial cells (Brg1fl/fl mice) were examined with immunohistochemistry and immunofluorescence assay for the number of surfactant-associated protein C (SFTPC)-positive cells in the pulmonary alveoli. The percentage of prosurfactant protein C (pro SP-C) positive cells in the lung tissues of the mice was analyzed with flow cytometry. Western blotting was used to detect the expression levels of pro SP-C, SFTPC, SFTPA and SFTPD in the lung tissues. The expression levels of cyclin D1 and the key proteins EGFR, p-EGFR, PI3K, p-PI3K, AKT, p-AKT, and NF-κB p65 in the proliferation-related signaling pathway were also detected with Western blotting. Results The results of immunohistochemistry and immunofluorescence assay revealed a significantly greater number of SFTPC-positive cells in Brg1fl/fl mice than in the WT mice (P < 0.05). Flow cytometry showed that the percentage of pro SP-C positive cells increased significantly in the lung tissues of Brg1fl/fl mice (P < 0.05). The expression levels of the functional proteins in AECⅡs, including proSP-C, SFTPC, SFTPA and SFTPD, were all significantly increased in Brg1fl/fl mice (P < 0.05); Brg1 knockout significantly promoted the expression of NF-κB p65 and CyclinD1 (P < 0.05) and increased the ratios of p-EGFR/EGFR, p-PI3K/PI3K and p-AKT/AKT in the lung tissue of the mice (P < 0.05). Conclusion Specific knockout of Brg1 in AECⅡs of C57BL/6 mice increases the number and enhances the functionality of AECⅡs possibly due to the activation of EGFR/PI3K/AKT/NF-κB signaling pathways and an increased protein expression of CyclinD1.

Keywords