Chinoy Mala R, Miller Shane A
Lung Development Research Program, Department of Surgery, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
Biol Neonate. 2006;90(3):185-96. doi: 10.1159/000093308. Epub 2006 May 12.
Tenascin-C (TN-C), an extracellular matrix glycoprotein, is crucial to cell-migration, proliferation, apoptosis and remodeling of tissues, with a potential role in pathobiology of pulmonary hypertension. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are crucial to the integrity of the extracellular matrix. TN-C and MMPs are counter-regulatory molecules, which influence the vascular integrity through modulations of elastin. We have a murine model of pulmonary hypoplasia with coexistent diaphragmatic hernia, vascular abnormalities and excessive arterial smooth muscle cell (SMC) proliferation.
Our objective was to investigate modulations of TN-C and MMPs in hypoplastic lungs and their possible contribution to the observed pulmonary vascular abnormalities.
We addressed our objectives by pursing immunoblotting and immunohistochemistry and zymography/reverse zymography to assess the alterations in activities of MMPs and their inhibitors.
We observed significant down-regulation of MMP-9 activity in hypoplastic lungs at the later fetal developmental stages, whereas MMP-2 activity assessed by gelatin zymography remained unaltered. Reverse zymography revealed up-regulation of activities of TIMP-1, -2, -3 and -4 in hypoplastic lungs during later fetal development, with pronounced increases in TIMP-3 and -4 activities. Furthermore, immunoblot analyses and immunohistochemistry revealed that TN-C protein was down-regulated in developing hypoplastic lungs, compared to normal lungs.
(1)TN-C is known to inhibit vascular SMC proliferation. But, decrease in TN-C in hypoplastic lungs may support the observed arterial SMC proliferation. (2) Our studies showed that in hypoplastic lungs the SMC apoptosis is not affected, thus suggesting that SMC proliferation and apoptosis may be two separate processes in pulmonary hypoplasia with coexistent diaphragmatic hernia. Together, our data showed an imbalance in the extracellular matrix proteins, which may contribute to the pulmonary vascular abnormalities.
腱生蛋白-C（TN-C）是一种细胞外基质糖蛋白，对细胞迁移、增殖、凋亡及组织重塑至关重要，在肺动脉高压的病理生物学中可能发挥作用。基质金属蛋白酶（MMPs）和金属蛋白酶组织抑制剂（TIMPs）对细胞外基质的完整性至关重要。TN-C和MMPs是相互调节的分子，它们通过调节弹性蛋白来影响血管完整性。我们有一个伴有膈疝、血管异常和动脉平滑肌细胞（SMC）过度增殖的肺发育不全小鼠模型。
我们的目的是研究发育不全肺中TN-C和MMPs的调节情况及其对观察到的肺血管异常的可能作用。
我们通过免疫印迹、免疫组织化学以及酶谱分析/反向酶谱分析来评估MMPs及其抑制剂活性的变化，以实现我们的目的。
我们观察到在胎儿发育后期，发育不全肺中MMP-9活性显著下调，而通过明胶酶谱法评估的MMP-2活性未发生改变。反向酶谱分析显示，在胎儿发育后期，发育不全肺中TIMP-1、-2、-3和-4的活性上调，其中TIMP-3和-4的活性显著增加。此外，免疫印迹分析和免疫组织化学显示，与正常肺相比，发育中的发育不全肺中TN-C蛋白下调。
（1）已知TN-C可抑制血管SMC增殖。但是，发育不全肺中TN-C的减少可能支持观察到的动脉SMC增殖。（2）我们的研究表明，发育不全肺中SMC凋亡未受影响，因此提示在伴有膈疝的肺发育不全中，SMC增殖和凋亡可能是两个独立的过程。总之，我们的数据显示细胞外基质蛋白失衡，这可能导致肺血管异常。
