Identification and characterization of testis specific ornithine decarboxylase antizyme (OAZ-t) gene: expression in haploid germ cells and polyamine-induced frameshifting.
BACKGROUND
Polyamines are known to play important roles in the proliferation and differentiation of many types of cells. However, in the testis, where polyamines such as spermidine and spermine exist in high concentrations, their roles still remains to be elucidated.


RESULTS
We have cloned a testis-specific gene encoding an ornithine decarboxylase antizyme known to control intracellular concentrations of polyamines in a feedback manner. The mRNA encoding the protein named ornithine decarboxylase antizyme in testis (OAZ-t) was specifically expressed in haploid germ cells. In contrast, the mRNA level of somatic ornithine decarboxylase antizyme 1 (OAZ1) decreased markedly at the late stages of haploid germ cell differentiation. OAZ-t mRNA was first observed in 23-day-old mice, whereas the OAZ-t protein was detected much later, at 35 days after birth. Further experiments on OAZ-t revealed that polyamines were capable of inducing a frameshifting at the frameshift sequence of OAZ-t mRNA, resulting in the translation of OAZ-t, as was the case with the somatic OAZ1. Transfection of OAZ-t cDNA inactivated the ornithine decarboxylase activity in the HEK293 cells.


CONCLUSIONS
Results indicate that the expression of OAZ-t is controlled at both transcriptional and translational levels, and that OAZ-t likely plays a key role in spermatogenesis by regulating the intracellular concentration of polyamines in haploid germ cells.
Tosaka
Y
Y
Department of Science for Laboratory Animal Experimentation, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita City, Osaka 565-0871, Japan.
Tanaka
H
H
Yano
Y
Y
Masai
K
K
Nozaki
M
M
Yomogida
K
K
Otani
S
S
Nojima
H
H
Nishimune
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D016466:CHO Cells; D002460:Cell Line; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018965:Frameshifting, Ribosomal / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D049452:Green Fluorescent Proteins; D006238:Haploidy; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009955:Ornithine Decarboxylase / Q000378:metabolism; D065108:Ornithine Decarboxylase Inhibitors; D011073:Polyamines / Q000494:pharmacology; D014176:Protein Biosynthesis / Q000187:drug effects; D020033:Protein Isoforms / Q000032:analysis / Q000235:genetics; D011506:Proteins / Q000032:analysis / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013094:Spermatozoa / Q000737:chemistry / Q000378:metabolism; D013737:Testis / Q000737:chemistry / Q000378:metabolism*
D018076:DNA, Complementary; D008164:Luminescent Proteins; D065108:Ornithine Decarboxylase Inhibitors; D011073:Polyamines; D020033:Protein Isoforms; D011506:Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C031017:ornithine decarboxylase antizyme; D049452:Green Fluorescent Proteins; D009955:Ornithine Decarboxylase