Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8675, Japan.
Amino Acids. 2012 Feb;42(2-3):565-75. doi: 10.1007/s00726-011-1034-8. Epub 2011 Sep 6.
Vascular smooth muscle cells (SMC) are able to proliferate when cultured on plates, but become differentiated when maintained in three-dimensional type I collagen matrices (honeycombs). SMC grown in honeycombs contained a low level of polyamines due to the presence of antizyme 1 (AZ1), a negative regulator of ornithine decarboxylase (ODC) and of polyamine uptake. To clarify the role of AZ1 in differentiation of SMC in honeycombs, an ODC gene was stably transfected into SMC (ODC-SMC). Although proliferation of ODC-SMC on plates was accelerated together with an increase in phosphorylated focal adhesion kinase (FAK) and a decrease in α-actin and myosin, maker proteins of differentiation, growth of ODC-SMC ceased in honeycombs similarly to normal SMC with a low level of phosphorylated FAK and a high level of α-actin and myosin. AZ1 expression in ODC-SMC on plates was low, but that in honeycombs was high. Antizyme in ODC-SMC in honeycombs not only decreased the level of ODC but also inhibited polyamine uptake activity. These results taken together suggest that low levels of polyamines caused by AZ1 in SMC in honeycombs inhibit phosphorylation of FAK and enhance expression of α-actin and myosin, resulting in differentiation through inhibition of focal adhesions.
血管平滑肌细胞（SMC）在培养板上能够增殖，但在三维 I 型胶原基质（蜂巢）中保持时会分化。由于存在抗酶 1（AZ1），SMC 在蜂巢中聚胺的水平较低，AZ1 是鸟氨酸脱羧酶（ODC）和聚胺摄取的负调节剂。为了阐明 AZ1 在 SMC 分化中的作用，将 ODC 基因稳定转染到 SMC 中（ODC-SMC）。尽管 ODC-SMC 在培养板上的增殖与磷酸化粘着斑激酶（FAK）的增加以及分化标志物蛋白α-肌动蛋白和肌球蛋白的减少同时加速，但与低磷酸化 FAK 和高α-肌动蛋白和肌球蛋白的正常 SMC 一样，ODC-SMC 在蜂巢中的生长也停止了。ODC-SMC 在培养板上的 AZ1 表达水平较低，但在蜂巢中的表达水平较高。蜂巢中 ODC-SMC 的抗酶不仅降低了 ODC 的水平，还抑制了聚胺摄取活性。这些结果表明，蜂巢中 SMC 中的 AZ1 导致聚胺水平降低，抑制 FAK 的磷酸化，增强α-肌动蛋白和肌球蛋白的表达，从而通过抑制粘着斑来促进分化。
