From the Klinik III für Innere Medizin, Universität zu Köln, Germany (M.V., J.J., E.M.B., L.M., X.C., T.K., M.Z., M.G., H.t.F., S.B., S.R.); Center for Molecular Medicine Cologne (CMMC), Universität zu Köln, Germany (M.V., J.J., E.M.B., L.M., X.C., T.K., M.Z., M.G., H.t.F., S.B., S.R.); Center for R&D, Uppsala University/County Council of Gävleborg, Gävle, Sweden (O.L.); Klinik für Herz- und Thoraxchirurgie, Universität zu Köln, Germany (M.S.); Cologne Cardiovascular Research Center (CCRC), Universität zu Köln, Germany (H.t.F., S.B., S.R.); Klinik für Kardiologie, Charité Universitätsmedizin, Berlin, Germany (F.B.); Institut für Experimentelle Medizin, Universität zu Köln, Germany (A.S.-K.); and Department of Cancer Biology, Dana Farber Cancer Institute, Boston, MA (J.J.Z.).
Arterioscler Thromb Vasc Biol. 2015 Jun;35(6):1434-44. doi: 10.1161/ATVBAHA.114.304887. Epub 2015 Apr 23.
Neointima formation after vascular injury remains a significant problem in clinical cardiology, and current preventive strategies are suboptimal. Phosphatidylinositol 3'-kinase is a central downstream mediator of growth factor signaling, but the role of phosphatidylinositol 3'-kinase isoforms in vascular remodeling remains elusive. We sought to systematically characterize the precise role of catalytic class IA phosphatidylinositol 3'-kinase isoforms (p110α, p110β, p110δ), which signal downstream of receptor tyrosine kinases, for vascular remodeling in vivo.
Western blot analyses revealed that all 3 isoforms are abundantly expressed in smooth muscle cells. To analyze their significance for receptor tyrosine kinases-dependent cellular responses, we used targeted gene knockdown and isoform-specific small molecule inhibitors of p110α (PIK-75), p110β (TGX-221), and p110δ (IC-87114), respectively. We identified p110α to be crucial for receptor tyrosine kinases signaling, thus affecting proliferation, migration, and survival of rat, murine, and human smooth muscle cells, whereas p110β and p110δ activities were dispensable. Surprisingly, p110δ exerted noncatalytic functions in smooth muscle cell proliferation, but had no effect on migration. Based on these results, we generated a mouse model of smooth muscle cell-specific p110α deficiency (sm-p110α(-/-)). Targeted deletion of p110α in sm-p110α(-/-) mice blunted growth factor-induced cellular responses and abolished neointima formation after balloon injury of the carotid artery in mice. In contrast, p110δ deficiency did not affect vascular remodeling in vivo.
Receptor tyrosine kinases-induced phosphatidylinositol 3'-kinase signaling via the p110α isoform plays a central role for vascular remodeling in vivo. Thus, p110α represents a selective target for the prevention of neointima formation after vascular injury, whereas p110β and p110δ expression and activity do not play a significant role.
血管损伤后的新内膜形成仍然是临床心脏病学中的一个重大问题，而目前的预防策略并不理想。磷酸肌醇 3'-激酶是生长因子信号的核心下游介质，但磷酸肌醇 3'-激酶同工型在血管重塑中的作用仍不清楚。我们试图系统地描述催化类 IA 磷酸肌醇 3'-激酶同工型（p110α、p110β、p110δ）在体内血管重塑中的精确作用，这些同工型信号下游的受体酪氨酸激酶。
Western blot 分析显示，所有 3 种同工型在平滑肌细胞中均大量表达。为了分析它们对受体酪氨酸激酶依赖性细胞反应的意义，我们分别使用了针对基因敲低和同工型特异性的 p110α（PIK-75）、p110β（TGX-221）和 p110δ（IC-87114）小分子抑制剂。我们发现 p110α 对于受体酪氨酸激酶信号至关重要，从而影响大鼠、小鼠和人平滑肌细胞的增殖、迁移和存活，而 p110β 和 p110δ 的活性则是可有可无的。令人惊讶的是，p110δ 在平滑肌细胞增殖中发挥非催化作用，但对迁移没有影响。基于这些结果，我们生成了平滑肌细胞特异性 p110α 缺陷（sm-p110α（-/-））的小鼠模型。在 sm-p110α（-/-）小鼠中靶向缺失 p110α 可减弱生长因子诱导的细胞反应，并在小鼠颈动脉球囊损伤后消除新内膜形成。相比之下，p110δ 缺陷并不影响体内血管重塑。
受体酪氨酸激酶诱导的磷酸肌醇 3'-激酶信号通过 p110α 同工型在体内对血管重塑起着核心作用。因此，p110α 是预防血管损伤后新内膜形成的选择性靶点，而 p110β 和 p110δ 的表达和活性则没有发挥重要作用。
