Screening of the key miRNA downstream of TLR2 and validating the function of miR-21 in radioprotection / 中华放射医学与防护杂志

ABSTRACT

Objective:To screen the key miRNA downstream of TLR2 and explore the function of the miR-21.Methods:Wild type (WT) and TLR2 KO mice were irradiated with 60Co γ-ray to compare their survivals. The downstream miRNAs of TLR2 signaling pathway were screened by RNA sequence in BMCs, and their expressions were verified by QT-PCR. Cell lines with overexpression or knockdown of a miRNA were established to evaluate the function of miRNA. Results:The radiosensitivity of TLR2 KO mice was higher than that of TLR2 WT mice( χ2=4.490, 13.100, 7.928, P<0.05). The bone marrow transplantation experiment proved that the increased radiosensitivity of TLR2 KO mice was related to BMCs ( χ2=4.291, P<0.05). A total of 55 differentially expressed genes were screened by RNA sequence ([log2 Fold Change]>0.95, Q<0.05), of which 28 were up-regulated and 27 were down-regulated. QT-PCR assay determined that miR-21 was down-regulated in BMCs of TLR2 KO ( t=9.420, P<0.01) and MyD88 KO ( t=10.700, P<0.01) mice. It was proved by QT-PCR that the expressions of IL-6 ( t=13.790, P<0.05) and TNF-α ( t=14.280, P<0.05) were increased in a TLR2 dependent manner after PAM3CSK4 stimulation. Overexpression of miR-21 promoted viability of EL4 cells ( t=5.951, P<0.05) and NIH/3T3 cells ( t=4.786, P<0.05) and reduced BMCs apoptosis in WT ( t=4.842, P<0.05) and TLR2 KO ( t=10.520, P<0.05) mice after radiation. Inhibition of miR-21 decreased the viability of EL4 cells ( t=4.815, P<0.05) and NIH/3T3 cells ( t=4.042, P<0.05). Conclusions:miR-21 plays a key regulatory role in the process of TLR2 radioprotection, which may be related to the up-regulation of IL-6 and TNF-α.