Research On The Function Of Regeneration Related MiRNAs In Planarians

microRNAs (miRNAs) are～22nt non-coding RNA that have been found in many eukaryotes.Mature miRNA down regulated the expresstion of taget genes by base pairing to target-mRNAs, causing translationalrepression or transcript degradation.As a kind of post-transcriptional negative regulators,miRNAs have been shown to play important roles in stem cell maintenance, cell differentiation, and regenerationPlanarians are flatworms of the phylum Platyhelminthes, which own incredible regeneration capcity. Planarians have a large population of stem cells known as neoblasts.When injure occurs, neoblasts will differentiate into new organs.Thus,the neoblasts amounts to adultsomatic stem cells.Planarians have become a molecularly tractable model system in which to study regeneration, tissue homeostasis, and stem-cell biology.To study the function of regenetation related miRNAs in planarians, the experiment first profiles the expression of miRNAs in the normal and regenerative tissues of planarians using miRCURY LNA array technology. Thirteen miRNAs showed significant differences in expression between these two tissues. The microarray-based experiments identified 8 over-expressed and 5 down-regulated miRNAs in the regenerative samples, which perhaps play important role in regeneration process. To further confirm the microarray results, sme-miR-2d which is over-expressed and sme-lin-4 which is down-regulated in regenerate tissue were selected and examined the expression by qRT-PCR.At present, the researh on the fuction of miRNAs is carried out mainly though performing the search on the target of the miRNA. In order to study the function of sme-lin-4 which is down-regulated in regenerate tissue, the 3'UTR date base in planarians was created, and the targed genes of sme-lin-4 were pridicted by MIRanda. To confirm the predict results, expresstion vector of sme-lin-4 is constructed at first, and then up regulated the expresstion level of sme-lin-4 using feeding method.Finally the expresstion pattern of five target genes was examined to confirm the predict results. According to our results, sme-lin-4 regulate the regeneration process by inhibiting the expresstion of Sm-like protein LSM14 gene. In this paper, using planarians as model system, regeneration related miRNAs in planarians were identified by microarray and part of their function during restoration and regeneration process was studyied.All of these provide new research approach and useful information for regeneration research.