Abstract 5575: Ca2+/Redox-Sensitive Tyrosine Kinase PYK2 Promotes Atherogenesis Through OxLDL/ROS/p21-Dependent Premature Senescence in Endothelium
Background: Calcium/redox-sensitive tyrosine kinase PYK2 plays crucial roles in cell migration. Analysis of PYK2-deficient macrophages has been reported that their directional migration was impaired due to dysfunction of PI3K, small GTPase Rho, and Ca (2+)-mobilization. Since monocyte/macrophage plays crucial role in atherogenesis, we newly generated the PYK2-knock-out mice and investigated the role of PYK2 in atherogenesis.
Methods: PYK2−/− mice (P-KO) were crossbred with ApoE−/− mice (E-KO), and PYK2−/−/ApoE−/− double knockout (D-KO) mice were established. Four-week-old mice were fed with high-fat-diet for 8 weeks, and the thoracic aorta and aortic root were histologically analyzed. Then we studied the mechanisms of their difference in atherogenesis.
Results: At the 8th week, atherosclerotic area of thoracic aorta in D-KO was less than E-KO (~54%, P<0.01, n=15, respectively). Numbers of infiltrating macrophage in D-KO mice was also reduced (~52%, P<0.01, n=15). We also verified that no significant difference in atherosclerotic area between E-KO recipient with D-KO bone marrow and D-KO recipient with E-KO bone marrow (n=6). At the 7th day, in E-KO aorta, we detected the senescence-associated-beta-gal staining area, however in D-KO aorta there is no area stained with SA-beta-gal. The expression of p21 was significantly increased in E-KO aorta at the 7th day, but in D-KO aorta there is no increase in p21 expression. In primary-cultured endothelial cells (ECs), Lysophosphatidylcholine (LPC) induced p21 expression in WT was significantly higher than that in P-KO. And we studied that these results were caused by ROS and JNK dependent pathway. The stained area with SA-beta-gal and the expression of p21 was impaired by intra peritoneal injection with JNK inhibitor (SA600125). The stained area with 8OHDG in E-KO was higher than that in D-KO, and the number of the stained endothelial cells with DCF in WT was much higher than that in P-KO. The expression of VCAM-1 and MCP-1 in E-KO was significantly increased than that in D-KO.
Conclusion: PYK2 promotes atherogenesis by inducing ROS/p21-dependent premature senescence and cytokine induction in endothelium