Berdal A, Lezot F, Pibouin L, Hotton D, Ghoul-Mazgar S, Teillaud C, Robert B, MacDougall M, Blin C
Laboratoire Biologie-Orofaciale et Pathologie, INSERM EMI-U 0110, Université Paris 7, IFR-58, Institut Biomédical des Cordeliers, 7, Paris, France.
Connect Tissue Res. 2002;43(2-3):148-52. doi: 10.1080/03008200290000970.
Msx1 plays a key role in early dental and cranio-facial patterning. A systematic screening of Msx1 transcripts during late postnatal stages of development evidenced not only sense mRNA but also antisense mRNA in the skeleton. Natural antisenses are able to bind their corresponding sense RNAs and block protein expression. Specific reverse-transcription polymerase chain reaction (RT-PCR) Northern-blotting using riboprobes and primer extension analysis allowed to identify and sequence a mouse 2184-base Msx1 antisense transcript. The transcription start site was located in a region including a consensus TATA box. In situ hybridization evidenced an increase in antisense mRNA expression during dental and bone cell differentiation in prenatal (Theiler stages E15.5-18.5) and newborn mice. This upregulation was related to Msx1 protein downregulation in cells expressing Msx1 sense mRNA. In vitro, transient Msx1 sense and antisense mRNA overexpression was performed in MO6-G3 cells, which pertain to the odontoblast lineage (polarization and dentin sialoprotein and phosphoprotein synthesis). The balance between antisense and sense Msx1 mRNAs appeared to control Msx1 protein levels. These data suggest that a bidirectional transcription of Msx1 homeogene may control Msx1 protein levels, and therefore may be critical in cell communication and differentiation during dental and cranio-facial development and mineralization.
Msx1在早期牙齿和颅面模式形成中起关键作用。在出生后发育后期对Msx1转录本进行的系统筛选表明，在骨骼中不仅存在正义mRNA，还存在反义mRNA。天然反义RNA能够结合其相应的正义RNA并阻断蛋白质表达。使用核糖探针的特异性逆转录聚合酶链反应（RT-PCR）、Northern印迹和引物延伸分析，得以鉴定并测序了一个2184个碱基的小鼠Msx1反义转录本。转录起始位点位于一个包含共有TATA框的区域。原位杂交表明，在产前（泰勒分期E15.5 - 18.5）和新生小鼠的牙齿及骨细胞分化过程中，反义mRNA表达增加。这种上调与表达Msx1正义mRNA的细胞中Msx1蛋白下调有关。在体外，在属于成牙本质细胞谱系（极化以及牙本质涎蛋白和磷蛋白合成）的MO6 - G3细胞中进行了Msx1正义和反义mRNA的瞬时过表达。反义与正义Msx1 mRNA之间的平衡似乎控制着Msx1蛋白水平。这些数据表明，Msx1同源基因的双向转录可能控制Msx1蛋白水平，因此在牙齿和颅面发育及矿化过程中的细胞通讯和分化中可能至关重要。
