Analysis Of The Matching Characteristics On The MRNAs And Their Target MRNA 3’UTR Sequences

MicroRNAs are important functional fragments that regulate gene expression,and they play an important role in the growth and development of plants and animals and in the occurrence of diseases.Based on mi Records and miRNAmap databases,we collected miRNAs and their target mRNAs 3’UTR match fragments sequences of higher animals H.sapiens,M.musculus and R.norvegicus and lower animal C.elegans.In this paper,we studied and compared the position preference of the interaction between higher animal and lower animal miRNAs fragments and their corresponding match fragments on the mRNAs3’UTR sequences,and discussed the effects of the G+C content and match rate of the two kinds of fragments on the position preference of the interaction.Finally,between miRNAs fragments and their match fragments the relationship between the four interaction modes and the G+C content and the match rate was analyzed.The main research contents are as follows:(1)The matching frequency distribution of higher animals H.sapiens,M.musculus and R.norvegicus miRNAs on their target mRNAs 3’UTR sequences was studied.It is found that the distribution of match frequency on the 3’UTR sequences has position preference.At the 5’ end and 3’ end of the 3’UTR sequence,there were obvious high matching regions,but the matching intensity at the 3’ end was relatively weak.Firstly,miRNAs fragments were classified according to G+C content.It was found that the matching frequency distributions of miRNAs with different G+C contents on 3’UTR sequences were significantly different.The matching frequency distributions of miRNAs with middle and high G+C contents on 3’UTR sequences showed a multi-peak structure and gradually decreased from 5’ to 3’ direction.We found that the location and matching intensity of the first peak distribution at the 5’ end of the 3’UTR sequences were conserved,which was basically independent of the G+C content of miRNAs fragments.Secondly,the match fragments corresponding to miRNAs were classified according to G+C content.It is found that with the increase of G+C content,the frequency value of the 5’end region of the 3’UTR sequence increases gradually,but the frequency value of the 3’ end region does not change significantly,and the weak peak region always exists.Thirdly,the interaction fragments pairs are classified according to the match rate.It is found that the match rate of the match fragments showed diversity in the wide 5’ end region and the relatively narrow 3’ end region on 3’UTR sequence.In conclusion,miRNAs in higher animals have multiple matching regions on the 3’UTR sequences of mRNAs,and their matching region preference is closely related to the G+C content of miRNAs,the G+C content of match fragments and the match rate,these results showed that miRNA and their target mRNAs 3’UTR sequences in higher animals were diverse in the regions of interaction,and that miRNAs have a wide range of adaptations to participate in gene expression.(2)The matching frequency distribution of lower animal C.elegans miRNAs on their target mRNAs 3’UTR sequences was studied.It is found that there is only one peak distribution of matching frequency on the 3’UTR sequence.The shape of the matching frequency distribution was not related to the G+C content of miRNAs,the G+C content of the match fragments and the size of the match rate.The average length of3’UTR of C.elegans is only 1/5 of that of higher animals,which is just in the first peak distribution region of higher animals,and they all have very similar characteristics.By comparison,we find that the first peak distribution region of the 3’UTR sequences in higher animals is the basic region or "seed" region of the 3’UTR,and C.elegans only exist in the basic region,while higher animals have evolved more interaction regions besides the basic region.With the development of species evolution,several functional regions were gradually added to the 3’UTR sequences to meet the needs of genes expression regulation In along the direction of3′ in higher animals.Our results show the evolutionary mechanism of the3’UTR sequences,and the broad adaptability of miRNAs to interact with their target mRNAs 3’UTR sequences is universal across species.(3)The relationship between the G+C content in miRNAs fragments of higher animals and C.elegans and the G+C content in corresponding match fragments was analyzed.It was found that miRNAs fragments with a certain G+C content can interact with match fragments with different G+C content,and the G+C content of match fragments that can interact with each other is widely distributed.This characteristic reflects that the diversity of miRNAs interaction with matching fragments and the high adaptability of matching patterns are the same among different species.(4)The interaction between miRNAs fragments and match fragments in higher animals and C.elegans was studied.The results showed that the main interaction modes in higher animals were normal type and missed type,and the main interaction modes in C.elegans were missed type and inserted type.And the interaction modes of miRNAs and their match fragments were related to the G+C content of these two fragments.The results showed that the interaction modes between miRNAs and match fragments were complex and varied,and there were differences among different species.(5)Match rate of miRNAs fragments in the 5’ region,middle region and 3’ region of higher animals and C.elegans was analyzed.The results showed that the 5’ region(the first 8 bases)was indeed the region with very high match rate,and the match rate of higher animals in this region was significantly higher than that of C.elegans.The average match rate of C.elegans in the middle region and 3’ region was higher than that of higher animals.In addition,our analysis showed that the probabilities of the four interaction modes in the three regions of miRNAs were different.The results showed that the various interaction patterns between miRNAs and match fragments were mainly determined by the middle region of miRNAs.(6)Sequences characteristics of miRNAs fragments in higher animals and C.elegans were studied.The results of the new symmetric relative entropy showed that the single base composition of the c-miRNAs fragments and the corresponding match fragments had high similarity,while the base pair composition was significantly different between them.We believe that this difference reflects the diversity of interaction modes,and there is a good similarity between species.In addition,the sequences structure(base association)of miRNAs fragments and match fragments was analyzed.The results showed that for both higher animals and C.elegans,the base association between miRNAs and the match fragment was relatively weak,which was significantly lower than that of the whole 3’UTR sequenced.Moreover,the base correlation of lower animal sequences was significantly weaker.These results indicate that miRNAs sequences have low sequences structure.This trait may be a strategy adopted by organisms in order to ensure the diversity of base matching during the regulation of genes expression.In conclusion,our study provides a new way to reveal the diversity of miRNAs involved in genes expression regulation,as well as the similarities and differences of miRNAs interacting with mRNA s3’UTR sequences between species.