NUDT16 and ITPA play a dual protective role in maintaining chromosome stability and cell growth by eliminating dIDP/IDP and dITP/ITP from nucleotide pools in mammals.
Mammalian inosine triphosphatase encoded by ITPA gene hydrolyzes ITP and dITP to monophosphates, avoiding their deleterious effects. Itpa(-) mice exhibited perinatal lethality, and significantly higher levels of inosine in cellular RNA and deoxyinosine in nuclear DNA were detected in Itpa(-) embryos than in wild-type embryos. Therefore, we examined the effects of ITPA deficiency on mouse embryonic fibroblasts (MEFs). Itpa(-) primary MEFs lacking ITP-hydrolyzing activity exhibited a prolonged doubling time, increased chromosome abnormalities and accumulation of single-strand breaks in nuclear DNA, compared with primary MEFs prepared from wild-type embryos. However, immortalized Itpa(-) MEFs had neither of these phenotypes and had a significantly higher ITP/IDP-hydrolyzing activity than Itpa(-) embryos or primary MEFs. Mammalian NUDT16 proteins exhibit strong dIDP/IDP-hydrolyzing activity and similarly low levels of Nudt16 mRNA and protein were detected in primary MEFs derived from both wild-type and Itpa(-) embryos. However, immortalized Itpa(-) MEFs expressed significantly higher levels of Nudt16 than the wild type. Moreover, introduction of silencing RNAs against Nudt16 into immortalized Itpa(-) MEFs reproduced ITPA-deficient phenotypes. We thus conclude that NUDT16 and ITPA play a dual protective role for eliminating dIDP/IDP and dITP/ITP from nucleotide pools in mammals.
Abolhassani
Nona
N
Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-8582, Japan.
Iyama
Teruaki
T
Tsuchimoto
Daisuke
D
Sakumi
Kunihiko
K
Ohno
Mizuki
M
Behmanesh
Mehrdad
M
Nakabeppu
Yusaku
Y
D017766:Acid Anhydride Hydrolases / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D043171:Chromosomal Instability; D007290:Inosine Diphosphate / Q000378:metabolism*; D007292:Inosine Nucleotides / Q000378:metabolism; D007293:Inosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D010641:Phenotype; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000097630:Inosine Triphosphatase
D017766:Acid Anhydride Hydrolases; D007290:Inosine Diphosphate; D007292:Inosine Nucleotides; D007293:Inosine Triphosphate; D011755:Pyrophosphatases; D000097630:Inosine Triphosphatase; C549898:deoxyinosine diphosphate; C065360:2'-deoxyinosine triphosphate; C549897:NUDT16 protein, mouse; C021446:inosine diphosphatase