Fasanaro Pasquale, Magenta Alessandra, Zaccagnini Germana, Cicchillitti Lucia, Fucile Sergio, Eusebi Fabrizio, Biglioli Paolo, Capogrossi Maurizio C, Martelli Fabio
Istituto Dermopatico dell'Immacolata-IRCCS, Via dei Monti di Creta 104, Rome 00167, Italy.
FASEB J. 2006 Jun;20(8):1242-4. doi: 10.1096/fj.05-4695fje. Epub 2006 Apr 7.
The understanding of endothelial cell responses to oxidative stress may provide insights into aging mechanisms and into the pathogenesis of numerous cardiovascular diseases. In this study, we examined the regulation and the functional role of cyclin D1, a crucial player in cell proliferation and survival. On H2O2 treatment, endothelial cells showed a rapid down-modulation of cyclin D1. Other D-cyclins were similarly regulated, and this decrease was also observed after exposure to other oxidative stress-inducing stimuli, namely 1,3-bis (2 chloroethyl)-1 nitrosourea treatment and ischemia. H2O2 treatment induced cyclin D1 ubiquitination followed by proteasome degradation. Phospholipase C inhibition prevented cyclin D1 degradation, and its activation triggered cyclin D1 down-modulation in the absence of oxidative stress. Activated phospholipase C generates inositol-1,4,5-trisphosphate (IP3) and Ca2+ release from internal stores. We found that both IP3-receptor inhibition and intracellular Ca2+ chelation prevented cyclin D1 degradation induced by oxidative stress. Furthermore, Ca2+ increase was transduced by Ca2+/calmodulin-dependent protein kinase (CaMK). In fact, H2O2 stimulated CaMK activity, CaMK inhibitors prevented H2O2-induced cyclin D1 down-modulation, and CaMK overexpression induced cyclin D1 degradation. Finally, overriding of cyclin D1 down-modulation via its forced overexpression or via CaMK inhibition increased cell sensitivity to H2O2-induced apoptotic cell death. Thus, cyclin D1 degradation enhances endothelial cell survival on oxidative stress.
对内皮细胞氧化应激反应的理解可能为衰老机制以及众多心血管疾病的发病机制提供见解。在本研究中，我们检测了细胞周期蛋白D1（细胞增殖和存活的关键因子）的调控及其功能作用。用H2O2处理后，内皮细胞显示出细胞周期蛋白D1的快速下调。其他D型细胞周期蛋白也受到类似调控，在暴露于其他氧化应激诱导刺激后，即1,3 - 双（2 - 氯乙基）-1 - 亚硝基脲处理和缺血后，也观察到这种下降。H2O2处理诱导细胞周期蛋白D1泛素化，随后被蛋白酶体降解。磷脂酶C抑制可防止细胞周期蛋白D1降解，而其激活在无氧化应激时触发细胞周期蛋白D1下调。活化的磷脂酶C产生肌醇-1,4,5 - 三磷酸（IP3）并从内部储存中释放Ca2+。我们发现IP3受体抑制和细胞内Ca2+螯合均能防止氧化应激诱导的细胞周期蛋白D1降解。此外，Ca2+增加由Ca2+/钙调蛋白依赖性蛋白激酶（CaMK）转导。事实上，H2O2刺激CaMK活性，CaMK抑制剂可防止H2O2诱导的细胞周期蛋白D1下调，而CaMK过表达诱导细胞周期蛋白D1降解。最后，通过强制过表达或CaMK抑制来克服细胞周期蛋白D1下调会增加细胞对H2O2诱导的凋亡性细胞死亡的敏感性。因此，细胞周期蛋白D1降解增强了内皮细胞在氧化应激下的存活能力。
