Extracellular signal-dependent nuclear import of STAT3 is mediated by various importin αs

Ryosuke Ushijima, Naoko Sakaguchi, Arihiro Kano, Atsushi Maruyama, Yoichi Miyamoto, Toshihiro Sekimoto, Yoshihiro Yoneda, Kenji Ogino, Taro Tachibana

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46 Citations (Scopus)


The signal transducer and activator of transcription 3 (STAT3) is a transcription factor that is involved in a variety of biological functions. STAT3 is activated by cytokines and growth factors via the phosphorylation of a tyrosine residue, dimerization, and subsequent nuclear translocation. However, the mechanism of its nuclear translocation is unclear. A study of the cytokine-stimulated import of STAT3 into the nucleus is reported herein. An oncostatin M (OSM)-dependent nuclear import assay system was first established in living cells. Using this system, we demonstrated that the microinjection of the importin α5/NPI-1 mutant, an anti-importin β antibody, and the RanQ69L mutant inhibited the nuclear import of STAT3. Second, we showed that tyrosine-phosphorylated STAT3 associates, not only with importin α5/NPI-1 but also with other importin αs, as a result of OSM stimulation, as evidenced by a solution binding assay. These findings suggest that the extracellular signal-dependent nuclear transport of STAT3 is mediated by various importin αs, importin β, and Ran.

Original languageEnglish
Pages (from-to)880-886
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number3
Publication statusPublished - May 13 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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