Gas6 inhibits apoptosis in vascular smooth muscle: role of Axl kinase and Akt
Gas6 inhibits apoptosis in vascular smooth muscle: role of Axl kinase and Akt
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DOI：
10.1016/j.yjmcc.2004.06.018
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发表时间：
2004-10-01
影响因子：
5
通讯作者：
Berk, BC
中科院分区：
文献类型：
--
作者：
Melaragno, MG;Cavet, ME;Berk, BC
Axl 是一种受体酪氨酸激酶，最初被鉴定为人骨髓性白血病细胞中的转化基因产物。此前，我们发现 Axl 表达与球囊损伤大鼠颈动脉中的新内膜形成相关，并且 Axl 表达受到血管紧张素 II 的高度调节。在本研究中，我们测试了 Axl 调节血管平滑肌细胞 (VSMC) 生长的机制，重点关注其抑制细胞凋亡的能力。用0％血清处理培养的大鼠主动脉VSMC 24It，导致19.8+/-1.4％的凋亡细胞。用 100 ng/ml Gas6（Axl 的推定配体）处理 VSMC 可使细胞凋亡减少至 8.9 +/- 0.7%（P = 0.002，N = 17），而用 10% 血清处理时细胞凋亡减少至 3.0 +/- 0.2%（P = 0.001，N = 17）。 Gas6 防止细胞凋亡的能力需要 Gas6 与 Axl 和 Axl 激酶活性结合，因为用可溶性竞争性 Axl 胞外结构域蛋白处理或转染激酶失活突变体 (Axl-K567R) 完全阻止了抗细胞凋亡作用。 Gas6-Axl 预防细胞凋亡需要激活磷脂酰肌醇 3-激酶 (PI3K)，如用 LY294002 处理或转染不结合 PI3K 的 Axl 缺失突变体 (Axl-DeltaPI3K) 所示。 ERK1/2 在 Gas6-Axl 的抗凋亡作用中没有显着作用，因为在用 Axl-DeltaPI3K 和 Axl-K567R 转染的细胞中保持了 ERK1/2 活性。这些发现确立了 Gas6-Axl-PI3K-Akt 通路作为 VSMC 的抗凋亡机制，可能在血管损伤反应中发挥重要作用。 (C) 2004 Elsevier Ltd. 保留所有权利。
Axl is a receptor tyrosine kinase originally identified as a transforming gene product in human myeloid leukemia cells. Previously, we showed that Axl expression correlated with neointima formation in balloon-injured rat carotid, and that Axl expression was highly regulated by angiotensin II. In the present study we tested the mechanisms by which Axl regulates vascular smooth muscle cell (VSMC) growth focusing on its ability to inhibit apoptosis. Treatment of cultured rat aortic VSMC for 24 It with 0% serum resulted in 19.8 +/- 1.4% apoptotic cells. Treatment of VSMC with 100 ng/ml Gas6 (the putative ligand for Axl) decreased apoptosis to 8.9 +/- 0.7% (P = 0.002, N = 17) as compared to a decrease with 10% serum to 3.0 +/- 0.2% (P = 0.001, N = 17). The ability of Gas6 to prevent apoptosis required both Gas6 binding to Axl and Axl kinase activity since treatment with a soluble, competitive Axl extracellular domain protein or transfection of a kinase inactive mutant (Axl-K567R) completely prevented the anti-apoptotic effect. Prevention of apoptosis by Gas6-Axl required activation of phosphatidyl inositol 3-kinase (PI3K) as shown by treatment with LY294002 or transfection of an Axl deletion mutant that does not bind PI3K (Axl-DeltaPI3K). There was no significant role for ERK1/2 in the anti-apoptotic effects of Gas6-Axl since ERK1/2 activity was maintained in cells transfected with Axl-DeltaPI3K and Axl-K567R. These findings establish the Gas6-Axl-PI3K-Akt pathway as an anti-apoptotic mechanism for VSMC that may be important in the response to vascular injury. (C) 2004 Elsevier Ltd. All rights reserved.