Almaidhan Asma, Cesario Jeffry, Landin Malt Andre, Zhao Yangu, Sharma Neeti, Choi Veronica, Jeong Juhee
Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, 10010 New York, NY, USA.
BMC Dev Biol. 2014 Jan 17;14:3. doi: 10.1186/1471-213X-14-3.
LIM domain binding protein 1 (LDB1) is a transcriptional co-factor, which interacts with multiple transcription factors and other proteins containing LIM domains. Complete inactivation of Ldb1 in mice resulted in early embryonic lethality with severe patterning defects during gastrulation. Tissue-specific deletions using a conditional knockout allele revealed additional roles of Ldb1 in the development of the central nervous system, hematopoietic system, and limbs. The goal of the current study was to determine the importance of Ldb1 function during craniofacial development in mouse embryos.
We generated tissue-specific Ldb1 mutants using Wnt1-Cre, which causes deletion of a floxed allele in the neural crest; neural crest-derived cells contribute to most of the mesenchyme of the developing face. All examined Wnt1-Cre;Ldb1(fl/-) mutants suffered from cleft secondary palate. Therefore, we performed a series of experiments to investigate how Ldb1 regulated palate development. First, we examined the expression of Ldb1 during normal development, and found that Ldb1 was expressed broadly in the palatal mesenchyme during early stages of palate development. Second, we compared the morphology of the developing palate in control and Ldb1 mutant embryos using sections. We found that the mutant palatal shelves had abnormally blunt appearance, and failed to elevate above the tongue at the posterior domain. An in vitro head culture experiment indicated that the elevation defect was not due to interference by the tongue. Finally, in the Ldb1 mutant palatal shelves, cell proliferation was abnormal in the anterior, and the expression of Wnt5a, Pax9 and Osr2, which regulate palatal shelf elevation, was also altered.
The function of Ldb1 in the neural crest-derived palatal mesenchyme is essential for normal morphogenesis of the secondary palate.
LIM结构域结合蛋白1（LDB1）是一种转录辅因子，它与多种转录因子以及其他含有LIM结构域的蛋白质相互作用。小鼠中Ldb1的完全失活导致早期胚胎致死，并在原肠胚形成过程中出现严重的模式缺陷。使用条件性敲除等位基因进行的组织特异性缺失揭示了Ldb1在中枢神经系统、造血系统和四肢发育中的其他作用。本研究的目的是确定Ldb1功能在小鼠胚胎颅面发育过程中的重要性。
我们使用Wnt1-Cre产生了组织特异性Ldb1突变体，Wnt1-Cre会导致在神经嵴中删除一个floxed等位基因；神经嵴衍生的细胞构成了发育中面部的大部分间充质。所有检测的Wnt1-Cre;Ldb1(fl/-)突变体均患有继发性腭裂。因此，我们进行了一系列实验来研究Ldb1如何调节腭部发育。首先，我们检测了正常发育过程中Ldb1的表达，发现Ldb1在腭部发育早期在腭间充质中广泛表达。其次，我们使用切片比较了对照和Ldb1突变体胚胎中发育中的腭部形态。我们发现突变体的腭突外观异常钝圆，并且在后部区域未能抬高到舌头上方。体外头部培养实验表明，抬高缺陷不是由于舌头的干扰。最后，在Ldb1突变体的腭突中，前部细胞增殖异常，并且调节腭突抬高的Wnt5a、Pax9和Osr2的表达也发生了改变。
Ldb1在神经嵴衍生的腭间充质中的功能对于继发性腭的正常形态发生至关重要。
