7-脱氢胆固醇还原酶基因沉默对体外培养小鼠腭突融合的影响

Inf luence of 7-dehydrocholesterol reductase gene silencing on the fusion of mouse palatal shelves

目的通过RNA干扰抑制7-脱氢胆固醇还原酶(Dhcr7)基因在培养腭突中的表达,研究Dhcr7基因对腭突融合的影响。方法根据C57BL/6J小鼠Dhcr7基因特异性的siRNA序列构建pAdTrack-CMV-siDhcr7,阳性克隆的pAdTrack-CMV-siDhcr7质粒进行体外重组,筛选出抗卡那霉素的重组腺病毒p Ad Easy-1-siDhcr7质粒,酶切后制备腺病毒载体DNA转染胚胎腭突。取妊娠13.5 d的小鼠胚胎腭突共30对随机分为3组,每组10对。正常对照组、空白腺病毒对照组和实验组均用不含胆固醇培养基培养腭突,其中空白腺病毒对照组加入空白腺病毒,实验组加入Dhcr7siRNA腺病毒。培养48 h后固定腭突并提取Dhcr7 mRNA和蛋白,采用扫描电子显微镜(SEM)观察腭突融合情况,采用逆转录聚合酶链反应(RT-PCR)和Western blot分析Dhcr7 mRNA和蛋白的含量。结果 SEM检测显示,正常对照组和空白腺病毒对照组在培养48 h时两侧腭突融合,形成连续的上腭;而实验组几乎没有生长,两侧腭突之间有很宽的裂隙。RT-PCR和Western blot检测显示,实验组Dhcr7 mRNA和蛋白表达与正常对照组和空白腺病毒对照组相比均明显减少,其差异有统计学意义(P<0.05)。结论 Dhcr7基因在腭突中的表达下调后,腭突融合失败,说明Dhcr7基因在腭突正常发育融合中起一定的作用。

Objective RNA interference was applied to knockdown the Dhcr7 gene in mouse embryonic palatal shelves to facilitate understanding of the function ofDhcr7 gene variants in the fusion of palatal shelves. Methods The pAdTrack- CMV-siDhcr7 was constructed using the specific siRNA sequence of Dhcr7 from C57BL/6J mouse. The pAdTrack-CMV- siDhcr7 of positive clones was reconstructed in vitro, and the recombinant adenovirus pAdEasy-l-siDhcr7 of kanamycin resistance was screened. The adenovirus vector DNA was then prepared for transfecting the embryonic palatal shelves. Thirty pairs of embryonic palatal shelves at 13.5 d gestational age were harvested and then randomly divided into the following three groups： normal control group （n= 10）, which included palatal shelves inculture medium without cholesterol; blank adenovirus control group （n=10）, which included palatal shelves in culture medium without cholesterol and blank adenovirus; and experi- mental group （n=10）, which included palatal shelves in culture medium without cholesterol and adenovirus encoding Dhcr7 siRNA. At 48 h after in vitro cultivation, the mRNA and protein of the palatal shelves were obtained for scanning electron microscopy （SEM）, reverse transcription polymerase chain reaction （RT-PCR）, and Western blot analyses. Results SEM showed that the palatal shelves of the normal control and blank adenovirus control groups fused and formed continuous palates, whereas those of the experimental group was almost undeveloped but exhibited large gaps between the two palatal shelves.RT-PCR and Western blot analyses showed that the mRNA and protein of Dhcr7 in the experimental group decreased compared with those in the normal control group with a sig- nificant difference （P〈0.05）. Conclusion Results indicate that Dhcr7 gene silencing affects the fusion of palatal shelves.Thus, Dhcr7 gene may serve a function in the normal development of palates.