Discovery of a spermatogenesis stage-specific ornithine decarboxylase antizyme: antizyme 3.
Previous studies with mice overproducing ornithine decarboxylase have demonstrated the importance of polyamine homeostasis for normal mammalian spermatogenesis. The present study introduces a likely key player in the maintenance of proper polyamine homeostasis during spermatogenesis. Antizyme 3 is a paralog of mammalian ornithine decarboxylase antizymes. Like its previously described counterparts, antizymes 1 and 2, it inhibits ornithine decarboxylase, which catalyzes the synthesis of putrescine. Earlier work has shown that the coding sequences for antizymes 1 and 2 are in two different, partially overlapping reading frames. Ribosomes translate the first reading frame, and just before the stop codon for that frame, they shift to the second reading frame to synthesize a trans-frame product. The efficiency of this frameshifting depends on polyamine concentration, creating an autoregulatory circuit. Antizyme 3 cDNA has the same arrangement of reading frames and a potential shift site with definite, although limited, homology to its evolutionarily distant antizyme 1 and 2 counterparts. In contrast to antizymes 1 and 2, which are widely expressed throughout the body, antizyme 3 transcription is restricted to testis germ cells. Expression starts early in spermiogenesis and finishes in the late spermatid phase. The potential significance of antizyme 3 expression during spermatogenesis is discussed in this paper.
Ivanov
I P
IP
Department of Human Genetics, University of Utah, 15 North 2030 East, Salt Lake City, UT 84112-5330, USA.
Rohrwasser
A
A
Terreros
D A
DA
Gesteland
R F
RF
Atkins
J F
JF
D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D004331:Drosophila melanogaster; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D065108:Ornithine Decarboxylase Inhibitors; D010802:Phylogeny; D011506:Proteins / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology*; D012671:Seminiferous Tubules / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012708:Sertoli Cells / Q000378:metabolism; D013091:Spermatogenesis / Q000502:physiology*; D013737:Testis / Q000378:metabolism; D014982:Xenopus laevis
D004791:Enzyme Inhibitors; D065108:Ornithine Decarboxylase Inhibitors; D011506:Proteins; C031017:ornithine decarboxylase antizyme