The Research On The Mechanisms Of The Muscle-specific MicroRNA’s Regulation In The Tongue’s Differentiation Of The Retinoic Acid Induced Tongue Dysplasia

Backgrounds: Cleft palate is one of the congenital malformation in oromaxillo-facialregion. It is the disease which caused by the interaction effects of gene and theenvironment. In our previous studies, we found that the retinoic acid (RA) induced cleftpalate mouse mode usually together with tongue dysplasia. The tongue of cleft palatemouse does not go down in embryonic day (E)14.5, so the two palatine processes arestill on the both sides of the tongue and have no place to fuse in the mid-line. In thisperiod, the cleft palate mouse’s tongue does not only have the disordered muscle fibers,but also has a different expression of myogenic regulatory factors (MRFs) compare withthe normal one. Muscles of tongue is a sort of skeletal muscle, so the gene whichregulate the development of skeletal muscle often play an important role in thedifferentiation of the muscles of tongue. Muscle-specific micrRNAs, also calledMyomiRs, play essential role in the myogenesis. MiR-206targets Pax7to up-regulatethe expression of MRFs to promote myogenesis. MiR-1has the similar seed sequenceswith miR-206, so it operates similarly to miR-206in the regulation of skeletal muscledevelopment. However, the research on the mechanisms of the muscle-specificmicrRNAs’ regulation in the tongue’s differentiation of the retinoic acid induced tonguedysplasia has not been reported.Aim: To research the mechanisms of the muscle-specific micrRNAs’ regulation in thetongue’s differentiation of the retinoic acid induced tongue dysplasia through test theexpression of MyomiRs, MRFs and Pax3/Pax7. Methods:10weeks ICR pregnant mouse of SPF level were selected. At embryonic10days,100mg/kg body weight retinoic acid was gavaged to pregnant mice to establish ancleft palate animal model. The tongues are collected in trizol at E13.5, E14.5, E15.5andE18.5. The expression levels of MyomiRs, MRFs and Pax3/Pax7were detected byreal-time quantitative PCR.Results:1. During the tongue development, the expression of miR-1and miR-206are keepingrising during the process and both reach the peak at E18.5.2. The expression of miR-1and miR-206in the cleft palate mouse’s tongue is less thantheir expression in the normal tongue. The results of miR-1in E14.5and E15.5havestatistical significance (p<0.01) and the results of miR-206in E13.5have statisticalsignificance (p<0.05).3. The expression of MyoD and myf5in the normal and cleft palate mouse’s tongueboth reach the peak at E14.5then reducing. At E13.5and E14.5, the expression ofMyoD in the cleft palate mouse’s tongue is less than its expression in the normaltongue. But at E15.5, the expression of MyoD in the cleft palate mouse’s tongue ishigher (p<0.01). And at both E14.5and E15.5, the expression of Myf5in the cleftpalate mouse’s tongue is less than its expression in the normal tongue.4. During the tongue myogenesis, both normal mouse and cleft palate mouse’stongues’ expression of Pax3reach the peak at E14.5, and their expression of Pax7reach the peak at E15.5. At E14.5, the expression of Pax3in the cleft palate mouse’stongue is higher than its expression in the normal tongue (p<0.05). And at E13.5,the expression of Pax7in the cleft palate mouse’s tongue is higher (p<0.01).Conclusions: During the tongue myogenesis, miR1/miR-206, Pax3/Pax7andMyf5/MyoD have correlation. In the retinoic acid induced tongue dysplasia, it still hasthat correlation. RA may down-regulate miR-1/miR-206which target on Pax3/Pax7,then down-regulate the expression of MyoD/Myf5to inhibit the myogenesis in tongueof cleft palate mouse, lead to the tongue dysplasia.