title: The spermidine analogue GC7 (N1-guanyl-1,7-diamineoheptane) induces autophagy through a mechanism not involving the hypusination of eIF5A.
abstract: The exogenous administration of spermidine promotes longevity in many model organisms. It has been proposed that this anti-age activity of spermidine is related to this polyamine's ability to promote autophagy. Since spermidine is the substrate for the eIF5A post-translational modification by hypusination, we asked ourselves whether mature eIF5A may represent the link between spermidine and autophagy induction. To test this hypothesis, we inhibited the conversion of native eIF5A by a pharmacological approach, using the N1-guanyl-1,7-diamineoheptane (GC7), a spermidine analogue which competitively and reversibly inhibits deoxyhypusine synthase (DHS). In addition, we also employed genetic approaches by ablating both the eIF5A protein itself and DHS, the rate limiting enzyme catalyzing the conversion of lysine to hypusine. Collectively the data presented in this study demonstrate that the mature eIF5A (hypusinated form) is not involved in the autophagic pathway and that the inhibitor of DHS, GC7, produces off-target effect(s) resulting in marked induction of basal autophagy. These data are relevant in light of the fact that GC7 is considered a potent and selective inhibitor of DHS and is a potential candidate drug for cancer, diabetes and HIV therapy.
authors.affiliation: Department of Biology, University of Rome 'Tor Vergata', Via Della Ricerca Scientifica, 00133, Rome, Italy.
authors.forename: Serafina
authors.initials: S
authors.lastname: Oliverio
authors.forename: Marco
authors.initials: M
authors.lastname: Corazzari
authors.forename: Claudia
authors.initials: C
authors.lastname: Sestito
authors.forename: Lucia
authors.initials: L
authors.lastname: Piredda
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ippolito
authors.forename: Mauro
authors.initials: M
authors.lastname: Piacentini
mesh_terms: D001343:Autophagy; D045744:Cell Line, Tumor; D005354:Fibrosarcoma / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology*; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives / Q000378:metabolism; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D013095:Spermidine / Q000031:analogs & derivatives / Q000378:metabolism*; D000097574:Eukaryotic Translation Initiation Factor 5A
chemical_list: D008239:Lysine; D000587:Oxidoreductases Acting on CH-NH Group Donors; D010448:Peptide Initiation Factors; D016601:RNA-Binding Proteins; D013095:Spermidine; D000097574:Eukaryotic Translation Initiation Factor 5A; C100028:hypusine; C063507:deoxyhypusine synthase