Involvement of the G-Protein-Coupled Receptor 4 in the Increased Expression of RANK/RANKL/OPG System and Neurotrophins by Nucleus Pulposus Cells under the Degenerated Intervertebral Disc-Like Acidic Microenvironment

Figure 2

The influence of GPR4 knockdown and overexpression in the expression of GPR4 and cAMP accumulation in the degenerated IVD-like acidic condition. Lentiviral vectors, including empty vehicle, shRNA, and DNA fragments encoding full-length rat GPR4, were applied for the knockdown and overexpression of GPR4, and successful transduction was verified on the GFP expression (a), the mRNA level (b), and protein level (c). cAMP accumulation in nucleus pulposus cells with GPR4 knockdown and overexpression was measured in pH 7.2 and pH 6.5 (d). Data were represented as of 6 independent experiments performed in triplicate; ANOVA was used to find out differences between cells in the same pH level and Student’s -test was used to find out differences within the same cell between pH 7.2 and 6.5. (GPR4 KD: GPR4 knockdown; GPR4 OE: GPR4 overexpression; ; ; ; ^§; ^§§; ^§§§).

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