Fig 2: JDP2 expression is upregulated in H/R-stimulated H9c2 cells, which activates PDE4B expression. (A) Western blotting and (B) RT-qPCR were performed to detect JDP2 expression in H/R-stimulated H9c2 cells. (C) JASPAR database was used to predict the binding sites between JDP2 and PDE4B promoter regions. (D) Dual luciferase reporter assays were performed to detect relative luciferase activities in cells co-transfected with PDE4B-WT or MUT and Oe-NC or Oe-JDP2. (E) Chromatin immunoprecipitation assays were performed to detect PDE4B enrichment in IgG and anti-JDP2 groups. (F) RT-qPCR was performed to assess the transfection efficiency of Oe-JDP2 in H9c2 cells. (G) RT-qPCR was performed to detect PDE4B mRNA expression levels after JDP2 overexpression in H9c2 cells. (H) RT-qPCR was performed to detect PDE4B mRNA expression in H/R-stimulated H9c2 cells following transfection with sh-PDE4B or co-transfection with Oe-JDP2. ***P<0.001. JDP2, c-Jun dimerization protein 2; H/R, hypoxia/reoxygenation; PDE4B, phosphodiesterase 4B; RT-qPCR, reverse transcription-quantitative PCR; WT, wild-type; MUT, mutant; Oe, overexpression; NC, negative control; sh, short hairpin RNA.

Fig 3: JDP2 overexpression partly reverses effect of PDE4B knockdown on H/R-induced cell apoptosis. (A) Apoptotic H9c2 cells and (B) the expression of apoptosis-related proteins in H/R-stimulated H9c2 cells following transfection with sh-PDE4B or co-transfection with Oe-JDP2. *P<0.05, **P<0.01 and ***P<0.001. JDP2, c-Jun dimerization protein 2; PDE4B, phosphodiesterase 4B; H/R, hypoxia/reoxygenation; sh, short hairpin RNA; Oe, overexpression; NC, negative control.