title: Divergent regulation of the key enzymes of polyamine metabolism by chiral alpha-methylated polyamine analogues.
abstract: The natural polyamines are ubiquitous multifunctional organic cations which play important roles in regulating cellular proliferation and survival. Here we present a novel approach to investigating polyamine functions by using optical isomers of MeSpd (alpha-methylspermidine) and Me2Spm (alpha,omega-bismethylspermine), metabolically stable functional mimetics of natural polyamines. We studied the ability of MeSpd and Me2Spm to alter the normal polyamine regulation pathways at the level of polyamine uptake and the major control mechanisms known to affect the key polyamine metabolic enzymes. These include: (i) ODC (ornithine decarboxylase), which catalyses the rate-limiting step of polyamine synthesis; (ii) ODC antizyme, an inhibitor of ODC and polyamine uptake; (iii) SSAT (spermidine/spermine N1-acetyltransferase), the major polyamine catabolic enzyme; and (iv) AdoMetDC (S-adenosyl-L-methionine decarboxylase), which is required for the conversion of putrescine into spermidine, and spermidine into spermine. We show that the stereoisomers differ in their cellular uptake and ability to downregulate ODC and AdoMetDC, and to induce SSAT. These effects are mediated by the ability of the enantiomers to induce +1 ribosomal frameshifting on ODC antizyme mRNA, to suppress the translation of AdoMetDC uORF (upstream open reading frame) and to regulate the alternative splicing of SSAT pre-mRNA. The unique effects of chiral polyamine analogues on polyamine metabolism may offer novel possibilities for studying the physiological functions, control mechanisms, and targets of the natural polyamines, as well as advance therapeutic drug development in cancer and other human health-related issues.
authors.affiliation: Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, Biocenter Kuopio, University of Kuopio, Kuopio 70210, Finland. mervi.hyvonen@uku.fi
authors.forename: Mervi T
authors.initials: MT
authors.lastname: Hyvönen
authors.forename: Michael T
authors.initials: MT
authors.lastname: Howard
authors.forename: Christine B
authors.initials: CB
authors.lastname: Anderson
authors.forename: Nikolay
authors.initials: N
authors.lastname: Grigorenko
authors.forename: Alex R
authors.initials: AR
authors.lastname: Khomutov
authors.forename: Jouko
authors.initials: J
authors.lastname: Vepsäläinen
authors.forename: Leena
authors.initials: L
authors.lastname: Alhonen
authors.forename: Juhani
authors.initials: J
authors.lastname: Jänne
authors.forename: Tuomo A
authors.initials: TA
authors.lastname: Keinänen
mesh_terms: D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D019175:DNA Methylation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004798:Enzymes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D011073:Polyamines / Q000138:chemical synthesis* / Q000378:metabolism* / Q000494:pharmacology; D013095:Spermidine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D013237:Stereoisomerism
chemical_list: D004798:Enzymes; D011073:Polyamines; C073193:1-methylspermidine; D013095:Spermidine