Moon Sung-Kwon, Cha Byung-Yoon, Lee Young-Choon, Nam Kyung-Soo, Runge Marschall S, Patterson Cam, Kim Cheorl-Ho
National Research Laboratory for Glycobiology, Korean Ministry of Science and Technology, Kyungju, Kyungbuk 780-714, South Korea.
Exp Gerontol. 2004 Jan;39(1):123-31. doi: 10.1016/j.exger.2003.09.019.
We previously reported that aortic smooth muscle cells (SMC) from aged mice have an age-related decline in proliferative capacity compared with those derived from young mice. Here we investigated matrix metalloproteinase-9 (MMP-9) regulation in both young and aged SMC. Zymography, immunoblot, and northern blot analysis showed that MMP-9 expression is significantly reduced in response to tumor necrosis factor-alpha stimulation with increasing in vitro age. Mutational analysis, gel shift assays and supershift assays demonstrated that the lower MMP-9 expression in aged SMC is associated with lower activities of NF-kappaB and AP-1. Since mitogen-activated protein kinase ERK1/2 induce MMP-9 expression, we examined whether U0126, an ERK1/2 inhibitor, influenced MMP-9 expression in aged SMC. Treatment with U0126 successfully inhibited MMP-9 expression in both young and aged SMC. Finally, to analyze the causal relationship between replicative senescence and MMP-9 expression, we stably overexpressed the MMP-9 gene in aged SMC and we showed no alteration of the proliferative capacity of the transduced cells. Taken together, these results suggest that down-regulation of MMP-9 expression in SMC may play a role in vascular remodeling during in vitro aging.
我们之前报道过，与年轻小鼠来源的主动脉平滑肌细胞（SMC）相比，老年小鼠的SMC增殖能力随年龄增长而下降。在此，我们研究了年轻和老年SMC中基质金属蛋白酶-9（MMP-9）的调控情况。酶谱分析、免疫印迹分析和Northern印迹分析表明，随着体外培养时间的增加，肿瘤坏死因子-α刺激后MMP-9的表达显著降低。突变分析、凝胶迁移实验和超迁移实验表明，老年SMC中MMP-9表达较低与NF-κB和AP-1的活性较低有关。由于丝裂原活化蛋白激酶ERK1/2可诱导MMP-9表达，我们研究了ERK1/2抑制剂U0126是否会影响老年SMC中MMP-9的表达。用U0126处理成功抑制了年轻和老年SMC中MMP-9的表达。最后，为了分析复制性衰老与MMP-9表达之间的因果关系，我们在老年SMC中稳定过表达MMP-9基因，结果显示转导细胞的增殖能力没有改变。综上所述，这些结果表明，SMC中MMP-9表达的下调可能在体外衰老过程中的血管重塑中起作用。
