Description

Importazole is a cell-permeable inhibitor of importin-β, which transports cargo molecules bearing a nuclear localization signal into the nucleus. Importazole prevents nuclear import of GFP-tagged nuclear factor of activated T cells (NFAT-GFP) in HEK293 cells (IC₅₀ = 15 μM), which is reversible upon importazole washout. Importazole does not interfere with transportin-mediated nuclear import or chromosomal maintenance 1 (CRM1)-mediated nuclear export. Importazole inhibits nuclear import of topoisomerase IIβ binding protein 1 (TopBP1) in Xenopus egg extracts and of NF-κB in multiple myeloma cells. It also induces defects in spindle and microtubule formation in vitro.

Uses

Importazole is an importin-β inhibitor.

Uses

Importazole has been used:

• to inhibit importin-β and to elucidate the mechanism of enhanced nuclear localization of heat shock protein 70 (HSP70) by vaccinia-related kinase 3 (VRK3)
• to treat COS7 cells transfected with the expressing vectors of WT HNF4α , S78A, and S78D to study its effect
• as a KPNB inhibitor to determine whether CREB-regulated co-activator 1 (CRTC1) would be escorted into the nucleus by the classical nuclear localizing sequence (NLS)- dependent machinery
• as a functional inhibitor of Importin β in embryo treatment
• as animportininhibitor to treat the transfected H1299 cells to block nuclear translocation of phosphorylated p53-RS

Definition

ChEBI: N-(1-phenylethyl)-2-(1-pyrrolidinyl)-4-quinazolinamine is a member of quinazolines.

Biochem/physiol Actions

Importazole is an inhibitor of importin-β transport receptors. During interphase, the transport receptor importin-β carries cargoes into the nucleus, where RanGTP releases them. Importazole somehow disrupts the importin/RAN interaction. Importazole is selective among other transporters. Compounds are imported into, but not out of, cells.

Background

Importazole is a cell-permeable, specific inhibitor of importin-β-mediated nuclear import. Nuclear import through importin β1 association with adaptor importin α is an essential component of the classical nuclear localization signal pathway. Following recognition of the cargo target NLS by importin α, the cargo:importin α:importin β1 complex is transported across the nuclear pore complex into the nucleus, where it dissociates by binding the small, GTP-bound GTPase Ran. Importazole blocks importin-β-mediated nuclear import by specifically inhibiting importin-β function, likely through altering the interaction between RanGTP and importin-β. Inhibition of the RanGTP/importin-β pathway by Importazole in mitotic cells results in multiple mitotic defects, including defects in spindle assembly, chromosome congression, and spindle centering. Similar results were seen in mouse oocytes, where Importazole treatment blocks meiosis I spindle formation and function.

References

[1] JONATHAN F. SODERHOLM. Importazole, a Small Molecule Inhibitor of the Transport Receptor Importin-β[J]. ACS Chemical Biology, 2011, 6 7: 700-708. DOI:10.1021/cb2000296
[2] STEPHEN L BIRD  Karsten W  Rebecca Heald. RanGTP and CLASP1 cooperate to position the mitotic spindle.[J]. Molecular Biology of the Cell, 2013, 24 16: 2506-2514. DOI:10.1091/mbc.e13-03-0150
[3] LIPING BAI  Shan Y  W Matthew Michael. Importin β-dependent nuclear import of TopBP1 in ATR–Chk1 checkpoint in Xenopus egg extracts[J]. Cellular signalling, 2014, 26 5: Pages 857-867. DOI:10.1016/j.cellsig.2014.01.006
[4] WENQING YAN . Importin β1 mediates nuclear factor-κB signal transduction into the nuclei of myeloma cells and affects their proliferation and apoptosis[J]. Cellular signalling, 2015, 27 4: Pages 851-859. DOI:10.1016/j.cellsig.2015.01.013
[5] ZHI-CHUAN ZHU. KPNB1 inhibition disrupts proteostasis and triggers unfolded protein response-mediated apoptosis in glioblastoma cells[J]. Oncogene, 2018, 37 22: 2936-2952. DOI:10.1038/s41388-018-0180-9