Background: C1q/tumor necrosis factor-related protein 3 (CTRP3) has been reported to be a crucial regulator in myocardial infarction. Nevertheless, the potential molecular mechanism of CTRP3 in ischemia/reperfusion (I/R) injury remains largely unclear.

Methods: The cell model of myocardial I/R injury was established by oxygen-glucose deprivation/reoxygenation (OGD/R) of rat cardiomyocyte H9C2. Expression of CTRP3 and lysosomal-associated membrane protein 1 (LAMP1) was detected in H9C2 cells treated with oxygen-glucose deprivation/reoxygenation (OGD/R). H9C2 cells were transfected with overexpression plasmids of CTRP3 (pcDNA-CTRP3) and LAMP1 (pcDNA-LAMP1), or CTRP3 small interfering RNA (si-CTRP3) or/and pcDNA-LAMP1, and cell proliferation, apoptosis and oxidative stress were testified. Co-IP assay was performed to validate the relationship among CTRP3, LAMP1 and JIP2. The role of CTRP3 and LAMP1 in JIP2/JNK pathway was evaluated with Western blot assay. Furthermore, in vivo myocardial I/R injury model was constructed to investigate the effect of CTRP3.

Results: Overexpression of CTRP3 and LAMP1 both significantly promoted cell proliferation, inhibited apoptosis and the production of reactive oxygen species (ROS), malondialdehyde (MAD) and cardiac troponin (cTn-I), while silencing CTRP3 exerted the opposite effects, and LAMP1 overexpression reversed the effect of silencing CTRP3 on the aspects above. CTRP3 interacted with LAMP1, and both CTRP3 and LAMP1 bound with JIP2. SP600125 (JNK inhibitor) could restore the effects of CTRP3 or LAMP1 overexpression on the expression of JIP2 and phosphorylated-JNK (p-JNK), proliferation and apoptosis. Moreover, overexpression of CTRP3 improved cardiac I/R injury in vivo.

Conclusion: CTRP3 alleviates cardiac I/R injury by elevating LAMP1 and activating JIP2/JNK signaling pathway, which may serve as a potential therapeutic target for I/R injury.