Mir-155 Downregulation by miRCURY LNA"! microRNA Inhibitor Can Increase alpha Chain Hemoglobins Expression in Erythroleukemic K562 Cell Line

MicroRNAs (miRNA) are small non-coding RNAs that have a distinguished role in post- transcriptional gene expression. It’s estimated that 10-30% of human mRNAs are regulated by miRNAs. Many miRNAs profiles change during normal erythropoiesis in which some of them are stage specific.mir-155 was downregulated 200 fold in erythropoiesis. K562cells were grown in RPMI1640 and viability tested by trypan blue. microRNA 155Inhibitor and its scramble were purchased from exiqon. K562 cells were transfected using transfection kit according to manufacture manual. After RNA extraction and cDNA synthesis, miRNA downregulation confirmed by miRNA Real time PCR, then alpha- and zeta- chain expression was investigated by RT and QRT-PCR. The viability of cells before transfection was 99% and the efficiency of mir-155 inhibitor transfection was 90%. By relative Q-PCR the zeta chain expression was increased 3.4 fold and alpha chain was increased 8.3 fold in comparison to untransfected cells. This study showed that mir-155 downregulation has a distinguished role in alpha chain hemoglobin mRNA expression level. The expression of alpha chain was more than zeta chain that may be result of adult source of K562 cells. Differentiation induction by miRNA regulation without adding any growth factor can be considered as a new strategy in gene therapy and tissue engineering.