Kochilas Lazaros K, Potluri Vijaya, Gitler Aaron, Balasubramanian Krithika, Chin Alvin J
Department of Pediatrics, Division of Pediatric Cardiology, Brown University Medical School, Providence, RI, USA.
Gene Expr Patterns. 2003 Oct;3(5):645-51. doi: 10.1016/s1567-133x(03)00108-x.
Tbx1 is one of the genes within the DiGeorge Critical Region (DGCR) and has been recently identified as the critical gene for the cardiovascular anomalies in the DiGeorge mouse models. We have cloned, sequenced and analyzed the zebrafish (Danio rerio) tbx1 cDNA. It encodes a protein of 460 amino acids that shares 64% identity and 67% similarity with the human TBX1 orthologue at the amino acid level. Although maternal expression was detected by RT-PCR, only zygotic expression could be detected by whole-mount in situ hybridization. Expression of zebrafish tbx1 by whole-mount in situ hybridization was first detected at 40% epiboly, 5.0 hours post fertilization (hpf) in the dorsal blastoderm margin. Through the stage of embryonic shield formation, tbx1 expression is restricted to the hypoblast, in the region of cells fated to become head and lateral plate mesoderm and pharyngeal endoderm. At 18 hpf, when the heart tube is beginning to assemble, three domains of tbx1 expression can be seen: cardiac precursors, pharyngeal arch precursors and otic vesicle. These three domains will remain the sites of tbx1 expression to varying degrees through at least 72 hpf. By 51 hpf, tbx1 expression can be seen in the cardiac outflow tract, the ventricle and the atrium, although by 72 hpf cardiac expression is strongest in the cardiac outflow tract. This newly identified tbx1 expression pattern in cardiac regions other than the cardiac outflow tract offers a new insight into the role of the tbx1 transcription factor in cardiac development.
Tbx1是迪乔治关键区域（DGCR）内的基因之一，最近已被确定为迪乔治小鼠模型中心血管异常的关键基因。我们已经克隆、测序并分析了斑马鱼（Danio rerio）的tbx1 cDNA。它编码一种由460个氨基酸组成的蛋白质，该蛋白质在氨基酸水平上与人TBX1直系同源物具有64%的同一性和67%的相似性。虽然通过RT-PCR检测到了母源表达，但通过整体原位杂交仅能检测到合子表达。通过整体原位杂交检测到斑马鱼tbx1的表达首先在受精后5.0小时（hpf）、卵裂球达到40%外包时，于背侧胚盘边缘被检测到。在胚胎盾形成阶段，tbx1的表达局限于下胚层，在注定会形成头部、侧板中胚层和咽内胚层的细胞区域。在18 hpf，当心脏管开始组装时，可以看到tbx1表达的三个区域：心脏前体、咽弓前体和耳泡。这三个区域将在至少72 hpf内不同程度地保持为tbx1的表达位点。到51 hpf时，在心脏流出道、心室和心房中可以看到tbx1的表达，尽管到72 hpf时，心脏流出道中的心脏表达最强。在心脏流出道以外的心脏区域新发现的这种tbx1表达模式，为tbx1转录因子在心脏发育中的作用提供了新的见解。
