Lhx6 and Lhx8 promote palate development through negative regulation of a cell cycle inhibitor gene, p57Kip2
Lhx6 and Lhx8 promote palate development through negative regulation of a cell cycle inhibitor gene, p57Kip2
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DOI：
10.1093/hmg/ddv223
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发表时间：
2015-09-01
影响因子：
3.5
通讯作者：
Jeong, Juhee
中科院分区：
文献类型：
--
作者：
Cesario, Jeffry M.;Malt, Andre Landin;Jeong, Juhee
腭裂是一种常见的人类先天缺陷。因此，从科学和医学的角度理解腭发育的分子遗传学是重要的。Lhx 6和Lhx 8编码LIM同源域转录因子，这两个基因在小鼠中的失活导致了严重的颅面缺陷，包括腭裂。在突变胚胎中，由于细胞增殖减少，腭的初始生长严重受损。通过全基因组转录谱分析，我们发现编码细胞周期抑制剂的p57（Kip 2）（Cdkn 1c）在Lhx 6（-/-）; Lhx 8（-/-）突变体的预期腭中上调。p57（Kip 2）与人类的Beckwith-Wiedemann综合征和IMAGe综合征有关，这是一种发育障碍，患者中腭缺陷的发生率增加。为了确定潜在的Lhx基因调控p57（Kip 2）的分子机制，我们结合染色质免疫沉淀，在硅片上搜索转录因子结合基序，并在体外报告分析与推定的顺式调控元件。这些实验的结果表明，LHX 6和LHX 8通过直接和间接机制调节p57（Kip 2），后者由叉头盒（FOX）家族转录因子介导。总之，我们的研究结果揭示了腭发育的启动与通过LHX的细胞周期抑制剂之间的新联系。我们提出了一个模型，其中Lhx 6和Lhx 8负调控p57（Kip 2）的表达在未来腭区，以允许足够的细胞增殖水平，从而促进正常腭发育。这是第一份阐明Lhx在腭发育中下游的分子遗传途径的报告。
Cleft palate is a common birth defect in humans. Therefore, understanding the molecular genetics of palate development is important from both scientific and medical perspectives. Lhx6 and Lhx8 encode LIM homeodomain transcription factors, and inactivation of both genes in mice resulted in profound craniofacial defects including cleft secondary palate. The initial outgrowth of the palate was severely impaired in the mutant embryos, due to decreased cell proliferation. Through genome-wide transcriptional profiling, we discovered that p57(Kip2) (Cdkn1c), encoding a cell cycle inhibitor, was up-regulated in the prospective palate of Lhx6(-/-); Lhx8(-/-) mutants. p57(Kip2) has been linked to Beckwith-Wiedemann syndrome and IMAGe syndrome in humans, which are developmental disorders with increased incidents of palate defects among the patients. To determine the molecular mechanism underlying the regulation of p57(Kip2) by the Lhx genes, we combined chromatin immunoprecipitation, in silico search for transcription factor-binding motifs, and in vitro reporter assays with putative cis-regulatory elements. The results of these experiments indicated that LHX6 and LHX8 regulated p57(Kip2) via both direct and indirect mechanisms, with the latter mediated by Forkhead box (FOX) family transcription factors. Together, our findings uncovered a novel connection between the initiation of palate development and a cell cycle inhibitor via LHX. We propose a model in which Lhx6 and Lhx8 negatively regulate p57(Kip2) expression in the prospective palate area to allow adequate levels of cell proliferation and thereby promote normal palate development. This is the first report elucidating a molecular genetic pathway downstream of Lhx in palate development.