Objective To investigate the impact of long non-coding RNA(LncRNA)taurine up-regulated gene 1(TUG1)on high glucose-induced cardiomyocyte apoptosis by regulating miR-181b-5p/programmed cell death protein 4(PDCD4)axis.Methods Diabetic cardiomyopathy(DCM)cell model was established in vitro with high glucose(HG,25 mmol/L glucose).AC16 cells were divided into the NG(5.5 mmol/L glucose)group,the HG group,the HG+sh-NC group,the HG+sh-TUG1 group,the HG+miR-NC group,the HG+miR-181b-5p group,the HG+sh-TUG1+anti-miR-NC group,the HG+sh-TUG1+anti-miR-181b-5p group,the HG+miR-181b-5p+pcDNA group and HG+miR-181b-5p+pc-PDCD4 group.The Cell Counting Kit-8(CCK-8)method was applied to detect cell viability.Lactate dehydrogenase(LDH)assay was applied to detect LDH release.Quantitative real-time polymerase chain reaction(qRT-PCR)was applied to detect expression levels of TUG1,miR-181b-5p and PDCD4 mRNA.Flow cytometry was applied to detect apoptosis.Western blot assay was applied to detect levels of B-cell lymphoma 2-associated X(Bax),activated caspase 3(cleaved caspase 3)and PDCD4 proteins.Caspase-Glo3 assay was applied to assess caspase 3 activity.Dual-luciferase reporter assay was applied to verify the targeting relationship between TUG1 or PDCD4 and miR-181b-5p.Results Compared with the NG group,the cell activity decreased in the HG group,and LDH release,apoptosis rate,Bax,cleaved caspase 3 expression and caspase 3 activity increased(P＜0.05),which could be antagonized by TUG1 knockdown or miR-181b-5p overexpression(P＜0.05).Inhibition of miR-181b-5p was able to alleviate the impact of TUG1 silencing on cardiomyocyte viability and apoptosis under high glucose treatment(P＜0.05).The overexpression of PDCD4 attenuated the promotion effect of miR-181b-5p up-regulation on the viability of cardiomyocytes treated with high glucose and the inhibitory effect on apoptosis.TUG1 was able to increase the expression of PDCD4 through adsorption of miR-181b-5p(P＜0.05).Conclusion TUG1 promotes high glucose-induced cardiomyocyte apoptosis by down-regulating miR-181b-5p and up-regulating PDCD4.