Schmidt Andreas, Marescau Bart, Boehm Ernest A, Renema W Klaas Jan, Peco Ruben, Das Anib, Steinfeld Robert, Chan Sharon, Wallis Julie, Davidoff Michail, Ullrich Kurt, Waldschütz Ralph, Heerschap Arend, De Deyn Peter P, Neubauer Stefan, Isbrandt Dirk
Center for Molecular Neurobiology Hamburg (ZMNH), Institute for Neural Signal Transduction, Hamburg, Germany.
Hum Mol Genet. 2004 May 1;13(9):905-21. doi: 10.1093/hmg/ddh112. Epub 2004 Mar 17.
We generated a knockout mouse model for guanidinoacetate N-methyltransferase (GAMT) deficiency (MIM 601240), the first discovered human creatine deficiency syndrome, by gene targeting in embryonic stem cells. Disruption of the open reading frame of the murine GAMT gene in the first exon resulted in the elimination of 210 of the 237 amino acids present in mGAMT. The creation of an mGAMT null allele was verified at the genetic, RNA and protein levels. GAMT knockout mice have markedly increased guanidinoacetate (GAA) and reduced creatine and creatinine levels in brain, serum and urine, which are key findings in human GAMT patients. In vivo (31)P magnetic resonance spectroscopy showed high levels of PGAA and reduced levels of creatine phosphate in heart, skeletal muscle and brain. These biochemical alterations were comparable to those found in human GAMT patients and can be attributed to the very similar GAMT expression patterns found by us in human and mouse tissues. We provide evidence that GAMT deficiency in mice causes biochemical adaptations in brain and skeletal muscle. It is associated with increased neonatal mortality, muscular hypotonia, decreased male fertility and a non-leptin-mediated life-long reduction in body weight due to reduced body fat mass. Therefore, GAMT knockout mice are a valuable creatine deficiency model for studying the effects of high-energy phosphate depletion in brain, heart, skeletal muscle and other organs.
我们通过对胚胎干细胞进行基因靶向操作，构建了一种用于胍基乙酸N-甲基转移酶（GAMT）缺乏症（MIM 601240，这是首个被发现的人类肌酸缺乏综合征）的基因敲除小鼠模型。小鼠GAMT基因第一个外显子中的开放阅读框被破坏，导致mGAMT中237个氨基酸中的210个被消除。在基因、RNA和蛋白质水平上验证了mGAMT无效等位基因的产生。GAMT基因敲除小鼠的大脑、血清和尿液中的胍基乙酸（GAA）显著增加，而肌酸和肌酐水平降低，这是人类GAMT患者的关键发现。体内（31）P磁共振波谱显示，心脏、骨骼肌和大脑中的磷酸胍基乙酸（PGAA）水平较高，而磷酸肌酸水平较低。这些生化改变与在人类GAMT患者中发现的改变相当，并且可归因于我们在人类和小鼠组织中发现的非常相似的GAMT表达模式。我们提供的证据表明，小鼠中的GAMT缺乏会导致大脑和骨骼肌中的生化适应性变化。它与新生儿死亡率增加、肌张力减退、雄性生育力下降以及由于体脂量减少导致的非瘦素介导的终身体重减轻有关。因此，GAMT基因敲除小鼠是一种有价值的肌酸缺乏模型，用于研究大脑、心脏、骨骼肌和其他器官中高能磷酸耗竭的影响。
