Targeted disruption of the inosine 5′-monophosphate dehydrogenase type I gene in mice
Targeted disruption of the inosine 5′-monophosphate dehydrogenase type I gene in mice
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DOI：
10.1128/mcb.23.18.6702-6712.2003
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发表时间：
2003-09-01
影响因子：
5.3
通讯作者：
Mitchell, BS
中科院分区：
文献类型：
--
作者：
Gu, JJ;Tolin, AK;Mitchell, BS
肌苷5 '-单磷酸脱氢酶（IMPDH）是鸟嘌呤核苷酸从头生物合成途径中的关键限速酶。两种单独的同工酶，命名为IMPDH I型和II型，有助于IMPDH活性。另一条途径通过次黄嘌呤-鸟嘌呤磷酸核糖基转移酶（HPRT）的活性来挽救鸟嘌呤，为细胞提供鸟嘌呤核苷酸。为了更好地理解IMPDH I型和II型以及HPRT对正常生物学功能的相对贡献，通过标准基因靶向技术产生IMPDH I型缺陷的小鼠，并与IMPDH II型缺陷或杂合的小鼠交配。在单基因敲除和双基因敲除小鼠中，抗CD 3+抗CD 28抗体引起的T细胞活化显著受损，而仅在两种酶均缺乏的小鼠中观察到对其他T细胞和B细胞有丝分裂原引起的更普遍的增殖抑制。此外，IMPDH I型-/- HPRT-/0脾细胞显示抗体活化后白细胞介素-4产生减少和细胞溶解活性受损，表明鸟嘌呤补救在补充鸟嘌呤核苷酸从头合成中的重要作用。我们得出结论，IMPDH和HPRT活动有助于正常的T淋巴细胞活化和功能。
Inosine 5'-monophosphate dehydrogenase (IMPDH) is the critical, rate-limiting enzyme in the de novo biosynthesis pathway for guanine nucleotides. Two separate isoenzymes, designated IMPDH types I and II, contribute to IMPDH activity. An additional pathway salvages guanine through the activity of hypoxanthine-guanine phosphoribosyltransferase (HPRT) to supply the cell with guanine nucleotides. In order to better understand the relative contributions of IMPDH types I and II and HPRT to normal biological function, a mouse deficient in IMPDH type I was generated by standard gene-targeting techniques and bred to mice deficient in HPRT or heterozygous for IMPDH type II. T-cell activation in response to anti-CD3 plus anti-CD28 antibodies was significantly impaired in both single- and double-knockout mice, whereas a more general inhibition of proliferation in response to other T- and B-cell mitogens was observed only in mice deficient in both enzymes. In addition, IMPDH type I-/- HPRT-/0 splenocytes showed reduced interleukin-4 production and impaired cytolytic activity after antibody activation, indicating an important role for guanine salvage in supplementing the de novo synthesis of guanine nucleotides. We conclude that both IMPDH and HPRT activities contribute to normal T-lymphocyte activation and function.