Department of Molecular Cardiovascular Biology and Pharmacology, Graduate School of Medicine, Ehime University, Tohon, Ehime 791-0295, Japan.
J Mol Cell Cardiol. 2009 Dec;47(6):798-809. doi: 10.1016/j.yjmcc.2009.09.006. Epub 2009 Sep 18.
Emerging new research suggests that the functions of the angiotensin (Ang) II type 1 (AT(1)) receptor are regulated in a complex manner. AT(1) receptor-associated protein (ATRAP) has been reported to reduce AT(1) receptor signaling with enhancement of AT(1) receptor internalization and to regulate the calcineurin/nuclear factor of activated T cells (NFAT) pathway. We examined the possibility that ATRAP could attenuate AT(1) receptor-mediated vascular senescence via inactivation with the calcineurin/NFAT pathway. Ang II stimulation significantly increased senescence-associated beta-galactosidase (SA-beta-gal)-stained cells, oxidative stress, and expression of p53 and p21 in wild-type (WT) vascular smooth muscle cells (VSMC). Moreover, in WT VSMC, Ang II stimulation enhanced NFAT transcriptional activity, which was prevented by CAML-siRNA treatment. NFAT-siRNA treatment attenuated Ang-II-increased SA-beta-gal activity and p53 and p21 expression. Treatment with a calcineurin activity inhibitor, cyclosporin A, reduced Ang-II-induced NFAT transcriptional activity and senescent VSMC. In contrast, VSMC prepared from ATRAP transgenic (ATRAP-Tg) mice exhibited attenuation of Ang-II-induced SA-beta-gal activity, oxidative stress, NFAT transcriptional activity, and expression of p53 and p21. Moreover, ATRAP-Tg VSMC showed a more reduction of Ang-II-induced NFAT transcriptional activity by CAML-siRNA treatment than WT VSMC. Furthermore, we demonstrated that in ATRAP-Tg VSMC, NFAT activity and senescent cells induced by ultraviolet irradiation were decreased compared with those in WT VSMC. Treatment with an AT(1) receptor blocker, valsartan, blocked these senescent cells but did not change NFAT activity in both cells. These results suggest that ATRAP negatively regulates VSMC senescence by reducing AT(1) receptor signaling, and that ATRAP-mediated inactivation of the calcineurin/NFAT pathway could be at least partly involved in prevention of VSMC senescence, irrespective of AT(1) receptor blockade in some conditions.
新出现的研究表明，血管紧张素（Ang）II 型 1（AT（1））受体的功能以复杂的方式受到调节。已经报道 AT（1）受体相关蛋白（ATRAP）通过增强 AT（1）受体内化来减少 AT（1）受体信号，并调节钙调神经磷酸酶/活化 T 细胞核因子（NFAT）途径。我们研究了 ATRAP 是否可以通过钙调神经磷酸酶/NFAT 途径失活来减轻 AT（1）受体介导的血管衰老。Ang II 刺激显着增加野生型（WT）血管平滑肌细胞（VSMC）中衰老相关的β-半乳糖苷酶（SA-β-gal）染色细胞、氧化应激以及 p53 和 p21 的表达。此外，在 WT VSMC 中，Ang II 刺激增强了 NFAT 转录活性，CAML-siRNA 处理可防止这种活性增强。NFAT-siRNA 处理可减轻 Ang-II 增加的 SA-β-gal 活性以及 p53 和 p21 的表达。钙调神经磷酸酶活性抑制剂环孢素 A 的处理降低了 Ang-II 诱导的 NFAT 转录活性和衰老的 VSMC。相比之下，来自 ATRAP 转基因（ATRAP-Tg）小鼠的 VSMC 显示出 Ang-II 诱导的 SA-β-gal 活性、氧化应激、NFAT 转录活性以及 p53 和 p21 表达的减弱。此外，与 WT VSMC 相比，ATRAP-Tg VSMC 中 CAML-siRNA 处理对 Ang-II 诱导的 NFAT 转录活性的抑制作用更强。此外，我们证明在 ATRAP-Tg VSMC 中，与 WT VSMC 相比，紫外线照射诱导的 NFAT 活性和衰老细胞减少。AT（1）受体阻滞剂缬沙坦阻断了这些衰老细胞，但对两种细胞的 NFAT 活性均无影响。这些结果表明，ATRAP 通过降低 AT（1）受体信号来负调控 VSMC 衰老，并且 ATRAP 介导的钙调神经磷酸酶/NFAT 途径失活至少部分参与了 VSMC 衰老的预防，无论在某些条件下是否阻断 AT（1）受体。
