Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, GA 30912, USA.
FEBS J. 2009 Nov;276(22):6603-14. doi: 10.1111/j.1742-4658.2009.07370.x. Epub 2009 Oct 8.
Alpha-defensins are released from granules of leukocytes and are implicated in inflammatory and fibrotic lung diseases. In the present study, the effects of alpha-defensins on the proliferation and collagen synthesis of lung fibroblasts were examined. We found that alpha-defensin-1 and alpha-defensin-2 induced dose-dependent increases in the incorporation of 5-bromo-2'-deoxy-uridine into newly synthesized DNA in two lines of human lung fibroblasts (HFL-1 and LL-86), suggesting that alpha-defensin-1 and alpha-defensin-2 stimulate the proliferation of lung fibroblasts. alpha-defensin-1 and alpha-defensin-2 also increased collagen-I mRNA (COL1A1) levels and protein contents of collagen-I and active/dephosphorylated beta-catenin without changes in total beta-catenin protein content in lung fibroblasts (HFL-1 and LL-86). Inhibition of the beta-catenin signaling pathway using quercetin prevented increases in cell proliferation and the protein content of collagen-I and active/dephosphorylated beta-catenin in lung fibroblasts, and in COL1A1 mRNA levels and collagen release into culture medium induced by alpha-defensin-1 and alpha-defensin-2. Knocking-down beta-catenin using small interfering RNA technology also prevented alpha-defensin-induced increases in cell proliferation and the protein content of collagen-I and active/dephosphorylated beta-catenin in lung fibroblasts, and in COL1A1 mRNA levels. Moreover, increases in the phosphorylation of glycogen synthase kinase 3beta, accumulation/activation of beta-catenin, and collagen synthesis induced by alpha-defensin-1 and alpha-defensin-2 were prevented by p38 mitogen-activated protein kinase inhibitor SB203580 and phosphoinositide 3-kinase inhibitor LY294002. These results indicate that alpha-defensin-1 and alpha-defensin-2 stimulate proliferation and collagen synthesis of lung fibroblasts. The beta-catenin signaling pathway mediates alpha-defensin-induced increases in cell proliferation and collagen synthesis of lung fibroblasts. alpha-defensin-induced activation of beta-catenin in lung fibroblasts might be caused by phosphorylation/inactivation of glycogen synthase kinase 3beta as a result of the activation of the p38 mitogen-activated protein kinase and phosphoinositide 3-kinase/Akt pathways.
α-防御素从白细胞颗粒中释放出来，并与炎症性和纤维性肺病有关。在本研究中，研究了 α-防御素对肺成纤维细胞增殖和胶原合成的影响。我们发现，α-防御素-1 和 α-防御素-2 诱导两条人肺成纤维细胞系（HFL-1 和 LL-86）中 5-溴-2'-脱氧尿苷掺入新合成 DNA 的剂量依赖性增加，表明 α-防御素-1 和 α-防御素-2 刺激肺成纤维细胞增殖。α-防御素-1 和 α-防御素-2 还增加了胶原-I mRNA（COL1A1）水平以及胶原-I 和活性/去磷酸化β-连环蛋白的蛋白含量，而肺成纤维细胞（HFL-1 和 LL-86）中的总β-连环蛋白蛋白含量没有变化。用槲皮素抑制 β-连环蛋白信号通路可防止肺成纤维细胞增殖和胶原-I 蛋白含量以及活性/去磷酸化β-连环蛋白增加，并可防止α-防御素-1 和 α-防御素-2 诱导的 COL1A1 mRNA 水平和胶原释放到培养基中。使用小干扰 RNA 技术敲低β-连环蛋白也可防止α-防御素诱导的肺成纤维细胞增殖和胶原-I 蛋白含量以及活性/去磷酸化β-连环蛋白增加，并可防止 COL1A1 mRNA 水平增加。此外，α-防御素-1 和 α-防御素-2 诱导的糖原合酶激酶 3β磷酸化增加、β-连环蛋白积累/激活以及胶原合成被 p38 丝裂原激活蛋白激酶抑制剂 SB203580 和磷脂酰肌醇 3-激酶抑制剂 LY294002 所阻止。这些结果表明，α-防御素-1 和 α-防御素-2 刺激肺成纤维细胞增殖和胶原合成。β-连环蛋白信号通路介导α-防御素诱导的肺成纤维细胞增殖和胶原合成增加。α-防御素诱导的肺成纤维细胞中β-连环蛋白的激活可能是由于糖原合酶激酶 3β的磷酸化/失活，这是由于 p38 丝裂原激活蛋白激酶和磷脂酰肌醇 3-激酶/Akt 途径的激活所致。
