Control and prevention of myocardial fibrosis using Pyk2-related non-kinase

Objective: To investigate the antifibrotic effect of Pyk2-related non-kinase (PRNK) and explore the possibility of using adenovirus carrying PRNK gene for targeted inhibition of Pyk2 to treat myocardial fibrosis.

Method: Adenovirus carrying PRNK gene was constructed and the angiotention II (Ang II)-induced rat cardiac fibroblasts (CFs) were transfected with the adenovirus. The expressions of PRNK and phosphorylated Pyk2 proteins in CFs were detected. After the preparation of rat model of abdominal aortic stenosis, the rats were infected by the adenovirus expressing PRNK gene. Four groups were set up: sham operation group, PRNK group, drug intervention group and operation group. Myocardial collagen volume fraction (CVF) and perivascular collagen area (PVCA) were measured through Van Gieson (VG) staining, and the content of blue-stained collagen was analyzed by Masson's trichrome staining. TUNEL method was used to detect myocardial cell apoptosis, and secretions of type I and IV collagen in myocardial tissues were detected by ELISA; expressions of PRNK and phosphorylated Pyk2 proteins were detected by Western Blot.

Results: Adenoviral vector carrying PRNK gene was successfully constructed; rat CFs were effectively transfected by the adenovirus that expressed PRNK gene stably. The adenoviruses were injected into rats with myocardial interstitial fibrosis via the tail vein. CVF, PVCA and grayscale of blue-stained collagen in the treatment groups were significantly lower than those in the control group, while the apoptosis rate of CFs in the former was significantly higher than that in the latter. In the transfection group, PRNK protein was upregulated in CFs, and the phosphorylated Pyk2 protein was downregulated. PPARγ agonist rosiglitazone (RSG) was injected as a comparison. The secretions of type I and IV collagen in myocardial tissues and serum did not show significant differences, and they were all much lower than those of the control.

Conclusion: Adenoviral vector provides an effective means for the transfer of genes in researches on the mechanism and prevention and control of myocardial fibrosis. Targeted inhibition of Pyk2 using PRNK is a new pathway to achieve an antifibrotic action. Highly expressed in CFs, PRNK inhibits myocardial fibrosis by inhibiting the phosphorylation of Pyk2 through competitive binding. We preliminarily demonstrate the feasibility of using adenoviral vector carrying PRNK gene for targeted inhibition of Pyk2 to treat myocardial fibrosis.