Inactivation of Rai1 in mice recapitulates phenotypes observed in chromosome engineered mouse models for Smith-Magenis syndrome
Inactivation of Rai1 in mice recapitulates phenotypes observed in chromosome engineered mouse models for Smith-Magenis syndrome
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DOI：
10.1093/hmg/ddi085
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发表时间：
2005-04-15
影响因子：
3.5
通讯作者：
Lupski, JR
中科院分区：
文献类型：
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作者：
Bi, WM;Ohyama, T;Lupski, JR
视黄酸诱导 1 (RAI1) 是在 Smith-Magenis 综合征 (SMS) 关键区域中发现的 20 个基因之一，SMS 是一种基因组疾病，具有多种先天性异常，与 17p11.2 的 3.7 Mb 杂合缺失相关。最近在 SMS 患者中发现了 RAI1 的杂合提前终止突变，但未检测到缺失。为了研究 Rai1 功能，我们通过基因打靶在小鼠中生成了无效等位基因，同时将 lacZ 报告基因插入 Rai1 基因座。 Rai1(+/-)小鼠的X-gal染色再现了Rai1的内源性表达模式。该基因主要在参与器官发生的上皮细胞中表达。在 Rai1(+/-) 小鼠中观察到肥胖和颅面异常，这些现象在含有同线性 SMS 关键区域杂合缺失的 SMS 小鼠模型中已被报道。因此，Rai1 的单倍体不足会导致小鼠肥胖和颅面畸形。有趣的是，Rai1(+/-) 小鼠中颅面异常的外显率进一步降低。大多数纯合小鼠在原肠胚形成和器官形成过程中死亡。幸存的 Rai1(-/-) 小鼠生长迟缓，颅面和中轴骨骼均出现畸形。使用绿色荧光蛋白和 GAL4 DNA 结合域与 Rai1 融合，我们发现 Rai1 易位到细胞核，并且具有反式激活活性。我们的数据与 Rai1 作为转录调节因子的功能一致，证明 Rai1 单倍体不足是 SMS 缺失小鼠的肥胖和颅面表型的原因，并表明 Rai1 对于胚胎和出生后发育很重要。
Retinoic acid induced 1 (RAI1) is among the 20 genes identified in the critical region of Smith-Magenis syndrome (SMS), a genomic disorder with multiple congenital anomalies associated with a 3.7 Mb heterozygous deletion of 17p11.2. Heterozygous premature termination mutations in RAI1 have been identified recently in SMS patients without detectable deletions. To investigate Rai1 function, we generated a null allele in mice by gene targeting and simultaneously inserted a lacZ reporter gene into the Rai1 locus. X-gal staining of the Rai1(+/-) mice recapitulated the endogenous expression pattern of Rai1. The gene was predominantly expressed in the epithelial cells involved in organogenesis. Obesity and craniofacial abnormalities, which have been reported in SMS mouse models containing a heterozygous deletion of the syntenic SMS critical region, were observed in Rai1(+/-) mice. Thus, haploinsufficiency of Rai1 causes obesity and craniofacial abnormalities in mice. Interestingly, the penetrance of craniofacial anomalies is further reduced in Rai1(+/-) mice. Most homozygous mice died during gastrulation and organogenesis. The surviving Rai1(-/-) mice were growth retarded and displayed malformations in both the craniofacial and the axial skeleton. Using green fluorescence protein and GAL4 DNA binding domain fusions to Rai1, we showed that Rai1 is translocated to the nucleus and it has transactivation activity. Our data are consistent with Rai1 functioning as a transcriptional regulator, document that Rai1 haploinsufficiency is responsible for obesity and craniofacial phenotypes in mice with SMS deletions, and indicate Rai1 is important for embryonic and postnatal developments.