Visualization of Fra-1/AP-1 activation during LPS-induced inflammatory lung injury using fluorescence optical imaging

Subbiah Rajasekaran, Chandramohan R. Tamatam, Haranatha R. Potteti, Venu Raman, Jae Woo Lee, Michael A. Matthay, Dolly Mehta, Narsa M. Reddy, Sekhar P. Reddy*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Inappropriate lung inflammatory response following oxidant and toxicant exposure can lead to abnormal repair and disease pathogenesis, including fibrosis. Thus early detection of molecular and cellular processes and mediators promoting lung inflammation is necessary to develop better strategies for therapeutic intervention and disease management. Previously, we have shown that transcription factor Fra-1/AP-1 plays key roles in lung inflammatory response, as Fra-1-null mice are less susceptible than wild-type mice to LPS-induced lung injury and mortality. Herein, we developed a transgenic reporter mouse model expressing tdTomato under the control of FRA-1 (human) promoter (referred to as FRA- 1TdTg mice) to monitor its activation during inflammatory lung injury using fluorescence protein-based optical imaging and molecular analysis in vivo and ex vivo. A higher red fluorescent signal was observed in the lungs of LPS-treated FRA-1TdTg mice compared with vehicle controls, and Western blot and qRT-PCR analyses revealed a significant correlation with the FRA-1-tdTomato reporter expression. Immunocolocalization demonstrated expression of FRA-1-tdTomato largely in lung alveolar macrophages and to some extent in epithelial cells. Moreover, we validated these results with a second reporter mouse model that expressed green fluorescent protein upon activation of endogenous Fra-1 promoter. Additionally, we demonstrated increased expression of FRA-1 in alveolar macrophages in human lung instilled with Escherichia coli ex vivo. Collectively, our data obtained from two independent reporter mouse models and from human samples underscore the significance of Fra-1 activation in alveolar macrophages during inflammatory lung injury and may aid in developing strategies to target this transcription factor in lung injury and repair.

Original languageEnglish (US)
Pages (from-to)L414-L424
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume309
Issue number4
DOIs
StatePublished - Aug 18 2015

Keywords

  • Acute lung injury
  • Fluorescence
  • Fra-1
  • In vivo imaging
  • TdTomato

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology

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