Abstract:
Haploinsufficiency of Meis homeobox 2 (MEIS2), encoding a transcriptional regulator, is associated with human cleft palate, and Meis2 inactivation leads to abnormal palate development in mice, implicating MEIS2 functions in palate development. However, its functional mechanisms remain unknown. Here we observed widespread MEIS2 expression in the developing palate in mice. Wnt1Cre -mediated Meis2 inactivation in cranial neural crest cells led to a secondary palate cleft. Importantly, about half of the Wnt1Cre ;Meis2f/f mice exhibited a submucous cleft, providing a model for studying palatal bone formation and patterning. Consistent with complete absence of palatal bones, the results from integrative analyses of MEIS2 by ChIP sequencing, RNA-Seq, and an assay for transposase-accessible chromatin sequencing identified key osteogenic genes regulated directly by MEIS2, indicating that it plays a fundamental role in palatal osteogenesis. De novo motif analysis uncovered that the MEIS2-bound regions are highly enriched in binding motifs for several key osteogenic transcription factors, particularly short stature homeobox 2 (SHOX2). Comparative ChIP sequencing analyses revealed genome-wide co-occupancy of MEIS2 and SHOX2 in addition to their colocalization in the developing palate and physical interaction, suggesting that SHOX2 and MEIS2 functionally interact. However, although SHOX2 was required for proper palatal bone formation and was a direct downstream target of MEIS2, Shox2 overexpression failed to rescue the palatal bone defects in a Meis2-mutant background. These results, together with the fact that Meis2 expression is associated with high osteogenic potential and required for chromatin accessibility of osteogenic genes, support a vital function of MEIS2 in setting up a ground state for palatal osteogenesis.
摘要:
Meis同源盒2(MEIS2)的单倍功能不全,编码转录调节因子,与人类腭裂有关,Meis2失活导致小鼠腭发育异常,MEIS2在腭发育中的功能。然而,其功能机制仍然未知。在这里,我们观察到MEIS2在小鼠发育中的腭中广泛表达。Wnt1Cre介导的Meis2在颅神经c细胞中的失活导致继发性腭裂。重要的是,大约一半的Wnt1Cre;Meis2f/f小鼠表现出粘膜下裂隙,提供了一个研究腭骨形成和模式的模型。与完全没有腭骨一致,通过ChIP测序对MEIS2进行综合分析的结果,RNA-Seq,转座酶可接近染色质测序的测定鉴定了直接受MEIS2调控的关键成骨基因,表明它在腭成骨中起着重要作用。从头基序分析发现,MEIS2结合区域高度富含几个关键成骨转录因子的结合基序,特别是身材矮小的homeobox2(SHOX2)。比较ChIP测序分析显示,除了在发育中的腭和物理相互作用中的共定位外,MEIS2和SHOX2的全基因组共占用。表明SHOX2和MEIS2在功能上相互作用。然而,尽管SHOX2是正常腭骨形成所必需的,并且是MEIS2的直接下游靶标,但在Meis2突变背景下,Shox2过表达未能挽救腭骨缺损.这些结果,Meis2表达与高成骨潜能相关,并且是成骨基因染色质可及性所必需的,支持MEIS2在建立pal骨形成基态方面的重要功能。