title: Napyradiomycins CNQ525.510B and A80915C target the Hsp90 paralogue Grp94.
abstract: The intracellular localization and target of the napyradiomycin congeners CNQ525.510B and A80815C were explored using an immunoaffinity fluorescence (IAF) approach. Semi-synthetic methods were used to prepare probes from napyradiomycin CNQ525.510B and derivative A80815C. The results of confocal microscopy indicated that probes from both natural products localized predominantly within the endoplasmic reticulum (ER) of HCT-116 human colon carcinoma cells. Parallel immunoaffinity precipitation efforts using a monoclonal antibody designed against the IAF tag, resulted in the isolation of an Hsp90 family member. This protein was identified as human Grp94 (hGrp94), by its specific mass spectral signature. This observation was validated by Western blot analyses and by the result of an in vitro Grp94 binding assay. The fact that the napyradiomycins CNQ525.510B and A80815C bind to hGrp94, and their associated probes localize within the ER, suggest the use of these materials as molecular probes for monitoring ER-based chaperone function.
authors.affiliation: Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0204, USA. wfenical@ucsd.edu.
authors.forename: Lauge
authors.initials: L
authors.lastname: Farnaes
authors.forename: James J
authors.initials: JJ
authors.lastname: La Clair
authors.forename: William
authors.initials: W
authors.lastname: Fenical
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry* / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D003511:Cyclohexanols / Q000737:chemistry* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D004721:Endoplasmic Reticulum / Q000737:chemistry; D005453:Fluorescence; D045325:HCT116 Cells; D006801:Humans; D018189:Immunomagnetic Separation; D008562:Membrane Glycoproteins / Q000032:analysis*; D008968:Molecular Conformation; D015335:Molecular Probes / Q000737:chemistry* / Q000494:pharmacology; D009285:Naphthoquinones / Q000737:chemistry* / Q000494:pharmacology; D013329:Structure-Activity Relationship
chemical_list: C000592272:A80915C; D000970:Antineoplastic Agents; D019086:Bridged Bicyclo Compounds, Heterocyclic; C000592271:CNQ525.510B; D003511:Cyclohexanols; D008562:Membrane Glycoproteins; D015335:Molecular Probes; D009285:Naphthoquinones; C053387:endoplasmin