GCN2是目前所有测序植物中唯一的eIF2α激酶,它可以通过磷酸化真核翻译起始因子eIF2α来调节蛋白的合成,从而对氨基酸的缺乏和各种胁迫做出响应。本研究采用RACE PCR技术从烟草K326中获得了GCN2的末端序列,通过RT-PCR方法获得了部分cDNA序列,经过拼接得到了GCN2的全长cDNA序列,将其命名为NtGCN2(GenBank登录号KJ706220)。分析发现, NtGCN2基因的cDNA全长为4196 bp, ORF全长为3759 bp,编码1252个氨基酸残基,分子量为141.4 kDa,等电点为5.58。BLASTP分析结果表明, NtGCN2与土豆和番茄的同源性分别达到90%和88%。对其蛋白质结构域进行预测发现, NtGCN2包含了典型的GCN2激酶功能域。荧光定量PCR分析表明,该基因在根、茎、叶和花中均有表达,在叶片中表达最强,根中的表达最弱。

Higher plants contain only a GCN2-type eIF2αkinase in their genome, which can phosphorylate the translation initiation factor eIF2αto regulate the general protein synthesis in response to amino acid starvation or stresses. In this study, we cloned the GCN2 from Nicotina tobaccum K326 by rapid ampliifcation of cDNA ends (RACE), named NtGCN2, which included a 3 759-bp open reading frame encoding 1 252 amino acid residues. The molecular weight of the predicted amino acid sequence of the NtGCN2 protein was 141.4 kDa with a theoretical pI of 5.58. Further, sequence alignment by BLASTP showed NtGCN2 shared the high simi-larity to Solanum tuberosum GCN2 (90%) and Solanum lycopersicum GCN2 (88%) and contained a typical ki-nase catalytic domain and a His-tRNA synthetase-related domain. Finally, Real-time PCR was porfermed to re-veal that NtGCN2 was expressed in roots, stems, leaves and lfowers, with higher expression in leaves and lower in roots.

目的 介绍3例先天性中枢性通气不良综合征(CCHS)患儿的临床特征及致病基因,探讨其分子遗传学的发病机制,并对相关文献进行回顾.方法 分析2008年3月至2012年4月收治的反复撤离呼吸机失败的3例患儿临床资料,分别在觉醒和睡眠状态下进行血气分析,利用基因序列测定和基因片段分析的方法进行检测,确定PHOX2B基因突变位点.结果 3例患儿清醒时有充足通气,但睡眠状态下肺泡通气不足伴频率正常的浅呼吸,血气分析均为高碳酸血症,睡眠时CO2分压持续高于60 mm Hg(1 mm Hg=0.133 kPa),符合CCHS的临床表现.PHOX2B基因测序分析发现例1PHOX2B第3外显子增加6个丙氨酸,例2和例3增加5个丙氨酸.结论 清醒时通气正常,睡眠时呼吸浅慢合并高碳酸血症是CCHS的主要临床表现,需要辅助呼吸支持.PHOX2B基因第3外显子中编码丙氨酸重复序列扩展突变,是3例患儿的分子发病原因.

Objective To evaluate clinical characteristics and PHOX2B gene mutations in congenital central hypoventilation syndrome (CCHS) and to facilitate the early diagnosis and management of CCHS and reduce the misdiagnosis.Method Clinical data of 3 infants with CCHS who had recurrent respiratory failure episodes and dependent on mechanical ventilation support in 3 from March 2008 to April 2012 were analyzed,and blood gas analysis was performed respectively in the awaken and sleeping status.Gene sequencing was used for detection of PHOX2B gene mutation.Result All the three patients had adequate ventilation during awaken time,but they presented with abnormal frequency and shallow breathing associated with alveolar hypoventilation after falling asleep.Blood gas analysis showed hypercapnia and CO2 partial pressure was consistently over 60 mm Hg (1 mm Hg =0.133 kPa) after falling asleep,which is in accordance with the clinical features of CCHS.The PHOX2B gene sequencing showed that 6 GCN repeats w