Description
Leptomycin B (87081-35-4) is an inhibitor of nuclear export of proteins. Acts via covalent binding to and inhibiting CRM1/exportin-1.1 Inhibits the nuclear export of the HIV regulatory protein Rev.2 Leptomycin B stabilizes p53 by blocking its nuclear export.3
Uses
Potent, specific inhibitor of nuclear export signal (NES)-dependent protein export from the nucleus
Uses
Leptomycin B is the dominant and most studied member of the leptomycin class, isolated from selected Streptomyces strains. Leptomycin B is a nanomolar active and specific nuclear export inhibitor. Its target is CRM1/exportin1, a protein in the nuclear export sequence (NES). Proteins affected include c-Abl, cyclin B1, HIV-1 Rev, IκB, MPF, MAP/ERK, MDM2/p53, NF-κB/IκB7 and PKA. Leptomycin B inhibits export of many RNAs, e.g. COX-2 and c-FOS mRNA. Leptomycin B also shows antifungal and antibacterial and potent antitumour activities.
Uses
Biological tool for studying nuclear localization and protein trafficking in eukaryotic cells.
Definition
ChEBI: A leptomycin having a (2E,10E,12E,16Z,18E)-double bond configuration as well as an ethyl substituent at position 17.
Biological Functions
Leptomycin B (LMB) is an unsaturated, branched-chain fatty acid that proved a potent tool in nuclear export studies. It was isolated from Streptomyces sp. strain ATS 1287. Until recently, LMB has been the only known small-molecule inhibitor of nuclear transport. The nuclear export inhibitor leptomycin B (LMB) prevents the export of proteins from the nucleus to the cytoplasm, protects p53 from Mdm2-mediated degradation, and potent inducer of p53 transcriptional activity. It is a specific inhibitor of the nuclear export of proteins containing leucine-rich nuclear export signal (NES). Supplementing sub-nanomolar concentrations of LMB to cultured cells caused inhibition of nuclear export of leucine-rich NES-bearing protein. Since its discovery as a potent inhibitor of nuclear export, a large number of shuttling proteins, performing a diverse range of cellular functions, are now known to accumulate in the nucleus.
General Description
Leptomycin B is an anti-fungal antibiotic, anti-tumor cytotoxin that inhibits CRM1-dependent, NES-dependent nucleo-cytoplasmic translocation (nuclear export inhibitor). NES containing proteins include HIV-1 REV; actin, c-Abl, cyclin B1, MDM2/p53, I?B, MPF, PKA and MEK.
Biological Activity
Antifungal antibiotic that is an inhibitor of the nuclear export of proteins; acts by binding directly to and inhibiting CRM1/exportin-1. Inhibits the nuclear export of the HIV regulatory protein Rev and stabilizes p53. Antitumor in vitro and in vivo .
Biochem/physiol Actions
Leptomycin B is an unsaturated, branched-chain fatty acid, and is an important tool in the study of nuclear export. Leptomycin B is a specific inhibitor of proteins containing nuclear export signal. Leptomycin B inhibits nucleo-cytoplasmic translocation of molecules such as the HIV-1 Rev protein and Rev-dependent export of mRNA. The addition of very small amounts to fibroblasts causes accumulation of MEK in the nucleus. Other proteins that are influenced by leptomycin?B are actin, c-Abl, cyclin B1, MDM2/p53, IκB, MPF, and PKA. The suggested inhibition mechanism involves the direct binding of leptomycin?B to CRM1, which blocks the binding of CRM1 to proteins containing the nuclear export signal, via the interaction with cysteine residue in CRM1 control conserved region.
Mechanism of action
The nuclear export inhibition mechanism involves the direct binding of Leptomycin B to exportin1, which blocks the binding of exportin1 to proteins containing the leucine-rich NES. Later, NES-exportin1 interaction was identified on a conserved region near cysteine-529 residue of human exportin1. This cysteine-529 residue on exportin1 provides LMB sensitivity because unsaturated γ-lactone in LMB undergoes a Michael-type reaction by the sulfhydryl group on cysteine residue. Once LMB is bound to exportin1, the NES-bearing nuclear export cargo fails to bind the receptor.
References
1) Kudo et al. (1998), Leptomycin B inhibition of signal-mediated nuclear export by direct binding to CRM1; Exp. Cell Res., 242 540
2) Wolff et al. (1997), Leptomycin B is an inhibitor of nuclear export: inhibition of nucleo-cytoplasmic translocation of the human immunodeficiency virus type 1 (HIV-1) Rev protein and Rev-dependent mRNA; Chem. Biol., 4 139
3) Freedman and Levine (1998), Nuclear export is required for degradation of endogenous p53 by MDM2 and human papillomavirus E6; Mol. Cell. Biol., 18 7288
