A new unique form of microRNA from human heart,microRNA-499c,promotes myofibril formation and rescues cardiac development in mutant axolotl embryos

Background: a recessive mutation c in the mexican axolotl,ambystoma mexicanum,results in the failure of normal heart development. in homozygous recessive embryos,the hearts do not have organized myofibrils and fail to beat. in our previous studies,we identified a noncoding myofibril-inducing rna (mir) from axolotls which promotes myofibril formation and rescues heart development. results: we randomly cloned rnas from fetal human heart. rna from clone #291 promoted myofibril formation and induced heart development of mutant axolotls in organ culture. this rna induced expression of cardiac markers in mutant hearts: tropomyosin,troponin and α-syntrophin. this cloned rna matches in partial sequence alignment to human microrna-499a and b,although it differs in length. we have concluded that this cloned rna is unique in its length,but is still related to the microrna-499 family. we have named this unique rna,microrna-499c. thus,we will refer to this rna derived from clone #291 as microrna-499c throughout the rest of the paper. conclusions: this new form,microrna-499c,plays an important role in cardiac development. © 2013 kochegarov et al.; licensee biomed central ltd.