The Role Of Methyltransferase METTL3 In Cardiomyocytes

N6-methyladenosine(m~6A)is a dynamic and reversible RNA post-transcriptional modification.It is catalytically installed by the methyltransferase complex.M6A methylation modification can be cleared by RNA demethylase.It is recognized by the‘Readers'protein containing YTH domain and post-transcriptional regulation.METTL3 is the first methyltransferase identified as the main catalytic component of the m~6A methyltransferase complex.From yeast to human,it is highly conserved among eukaryotes.METTL3 plays an important role in many biological processes such as cell proliferation,cancer occurrence,cell migration and invasion,stem cell differentiation and viability.At present,the role of METTL3 in normal cardiomyocytes has not been reported.In this study,combined with the HPA RNA-seq results of METTL3 in normal human tissues in the NCBI GENE database,mouse heart tissues of different periods were collected for Western Blot experiments to detect the expression of METTL3 protein in mouse heart tissues of different periods.It is highly expressed in human and mouse heart tissues.In the published m~6A-seq data of HEK293T cells,we found that Tbx3,Tbx2,Yap1,Nkx2.5,Hand2,and Mef2a all play an important role in cardiac tissue,showing high methylation richness.For the above six genes that may be methylated,MeRIP-qPCR was detected in normal and cardiomyocytes after METTL3 knockdown.The results showed that the mRNAs of the above six genes showed m6A status in normal cardiomyocytes and after knocking down METTL3,the level of m6A methylation on gene transcripts decreased.Knockdown/overexpression of METTL3 in H9C2 cardiomyocytes,it was found that knocking down METTL3 can inhibit the proliferation of cardiomyocytes while overexpression of METTL3 can promote cell proliferation;the expression changes of the above six genes were tested,and the results showed that METTL3 had a negative regulatory effect on the expression of Tbx3 gene,and had no significant effect on the expression of other genes.Knocking down the TBX3 promotes cell proliferation.Further mechanism research found that METTL3 relies on its methyltransferase activity to regulate the downstream Tbx3 gene expression and participate in the proliferation of cardiomyocytes.The role of METTL3 in myocardial cells in this experiment can provide new ideas for clinical treatment of heart disease.