title: A highly sensitive prenylation assay reveals in vivo effects of bisphosphonate drug on the Rab prenylome of macrophages outside the skeleton.
abstract: Bisphosphonate drugs such as zoledronic acid (ZOL), used for the treatment of common bone disorders, target the skeleton and inhibit bone resorption by preventing the prenylation of small GTPases in bone-destroying osteoclasts. Increasing evidence indicates that bisphosphonates also have pleiotropic effects outside the skeleton, most likely via cells of the monocyte/macrophage lineage exposed to nanomolar circulating drug concentrations. However, no effects of such low concentrations of ZOL have been reported using existing approaches. We have optimized a highly sensitive in vitro prenylation assay utilizing recombinant geranylgeranyltransferases to enable the detection of subtle effects of ZOL on the prenylation of Rab- and Rho-family GTPases. Using this assay, we found for the first time that concentrations of ZOL as low as 10nM caused inhibition of Rab prenylation in J774 macrophages following prolonged cell culture. By combining the assay with quantitative mass spectrometry we identified an accumulation of 18 different unprenylated Rab proteins in J774 cells after nanomolar ZOL treatment, with a >7-fold increase in the unprenylated form of Rab proteins associated with the endophagosome pathway (Rab1, Rab5, Rab6, Rab7, Rab11, Rab14 and Rab21). Finally, we also detected a clear effect of subcutaneous ZOL administration in vivo on the prenylation of Rab1A, Rab5B, Rab7A and Rab14 in mouse peritoneal macrophages, confirming that systemic treatment with bisphosphonate drug can inhibit prenylation in myeloid cells in vivo outside the skeleton. These observations begin a new era in defining the precise pharmacological actions of bisphosphonate drugs on the prenylation of small GTPases in vivo.
authors.affiliation: a Garvan Institute of Medical Research and St Vincent's Clinical School; UNSW Australia ; Sydney , Australia.
authors.forename: Naveid
authors.initials: N
authors.lastname: Ali
authors.affiliation: a Garvan Institute of Medical Research and St Vincent's Clinical School; UNSW Australia ; Sydney , Australia.
authors.forename: Julie
authors.initials: J
authors.lastname: Jurczyluk
authors.affiliation: b Institute of Medical Sciences; University of Aberdeen ; Aberdeen , UK.|e H. Lee Moffitt Cancer Center ; Tampa , FL USA.
authors.forename: Gemma
authors.initials: G
authors.lastname: Shay
authors.affiliation: c Institute for Molecular Bioscience; The University of Queensland ; Queensland , Australia.
authors.forename: Zakir
authors.initials: Z
authors.lastname: Tnimov
authors.affiliation: c Institute for Molecular Bioscience; The University of Queensland ; Queensland , Australia.
authors.forename: Kirill
authors.initials: K
authors.lastname: Alexandrov
authors.affiliation: a Garvan Institute of Medical Research and St Vincent's Clinical School; UNSW Australia ; Sydney , Australia.
authors.forename: Marcia A
authors.initials: MA
authors.lastname: Munoz
authors.affiliation: a Garvan Institute of Medical Research and St Vincent's Clinical School; UNSW Australia ; Sydney , Australia.
authors.forename: Oliver P
authors.initials: OP
authors.lastname: Skinner
authors.affiliation: d University of Western Australia ; Perth , Australia.
authors.forename: Nathan J
authors.initials: NJ
authors.lastname: Pavlos
authors.affiliation: a Garvan Institute of Medical Research and St Vincent's Clinical School; UNSW Australia ; Sydney , Australia.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rogers
mesh_terms: D000818:Animals; D002460:Cell Line; D004164:Diphosphonates / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology*; D017737:Macrophages, Peritoneal / Q000378:metabolism*; D051379:Mice; D017368:Protein Prenylation / Q000187:drug effects*; D000077211:Zoledronic Acid; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D004164:Diphosphonates; D007093:Imidazoles; D000077211:Zoledronic Acid; D020691:rab GTP-Binding Proteins
keywords: Rab; bisphosphonate; geranylgeranyl transferase; macrophage; prenylation