Upregulation of Robo4 expression by SMAD signaling suppresses vascular permeability and mortality in endotoxemia and COVID-19 models

Maaya Morita, Aki Yoneda, Nagisa Tokunoh, Tatsumi Masaki, Keisuke Shirakura, Mayumi Kinoshita, Rina Hashimoto, Naoya Shigesada, Junya Takahashi, Masashi Tachibana, Shota Tanaka, Masanori Obana, Nobumasa Hino, Masahito Ikawa, Chikako Ono, Yoshiharu Matsuura, Hiroyasu Kidoya, Nobuyuki Takakura, Yoshiaki Kubota, Takefumi DoiKazuo Takayama, Kazutake Tsujikawa, Yasuo Yoshioka, Yasushi Fujio, Yoshiaki Okada

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


There is an urgent need to develop novel drugs to reduce the mortality from severe infectious diseases with the emergence of new pathogens, including Coronavirus disease 2019 (COVID-19). Although current drugs effectively suppress the proliferation of pathogens, immune cell activation, and inflammatory cytokine functions, they cannot completely reduce mortality from severe infections and sepsis. In this study, we focused on the endothelial cell-specific protein, Roundabout 4 (Robo4), which suppresses vascular permeability by stabilizing endothelial cells, and investigated whether enhanced Robo4 expression could be a novel therapeutic strategy against severe infectious diseases. Endothelial-specific overexpression of Robo4 suppresses vascular permeability and reduces mortality in lipopolysaccharide (LPS)-treated mice. Screening of small molecules that regulate Robo4 expression and subsequent analysis revealed that two competitive small mothers against decapentaplegic (SMAD) signaling pathways, activin receptor-like kinase 5 (ALK5)-SMAD2/3 and ALK1-SMAD1/5, positively and negatively regulate Robo4 expression, respectively. An ALK1 inhibitor was found to increase Robo4 expression in mouse lungs, suppress vascular permeability, prevent extravasation of melanoma cells, and decrease mortality in LPS-treated mice. The inhibitor suppressed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced endothelial barrier disruption and decreased mortality in mice infected with SARS-CoV-2. These results indicate that enhancing Robo4 expression is an efficient strategy to suppress vascular permeability and mortality in severe infectious diseases, including COVID-19, and that small molecules that upregulate Robo4 can be potential therapeutic agents against these diseases.

Original languageEnglish
Article numbere2213317120
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number3
Publication statusPublished - 2023 Jan 17


  • COVID-19
  • Roundabout 4
  • SMAD
  • infectious disease
  • vascular permeability

ASJC Scopus subject areas

  • General


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