Miano J M, Vlasic N, Tota R R, Stemerman M B
Department of Experimental Pathology, New York Medical College, Valhalla 10595.
Am J Pathol. 1993 Mar;142(3):715-24.
The availability of specific reagents to measure gene activity has provided important tools and potential new directions for the study of smooth muscle cell (SMC) proliferation in vivo. In this report, we have measured steady-state mRNA levels of several fos and jun family members in aortic tissue by Northern blotting after vascular injury. In addition, protein products of these genes were analyzed by immunocytochemistry. Within 15 minutes of balloon injury, mRNA levels of c-fos, fosB, c-jun, junB, and junD were elevated severalfold. In contrast, fos-related antigen (fra-1) mRNA showed a delayed onset of expression. The expression kinetics of these immediate early genes was similar to those in cultured cells stimulated to undergo proliferation by growth factors, suggesting that such SMC gene activation in vivo reflects permeation of blood-derived growth factors into the vessel wall or intravascular release of preformed growth factors. Translation of fos and jun genes into immunoreactive products was demonstrated 2 hours after balloon injury with antisera to Fos and Jun proteins. Treating rats with cycloheximide abolished this immunoreactivity. The distribution of Fos and Jun products was concentrated in SMC nuclei at the luminal border of the rat aorta. Such focal expression may have consequences for the initiation of SMC DNA synthesis and migration after vascular injury. Furthermore, the expression of Fos and Jun proteins in SMC after vascular balloon injury may be used as an index of SMC activation under a variety of experimental settings.
用于测量基因活性的特异性试剂的可用性为体内平滑肌细胞（SMC）增殖的研究提供了重要工具和潜在的新方向。在本报告中，我们在血管损伤后通过Northern印迹法测量了主动脉组织中几种fos和jun家族成员的稳态mRNA水平。此外，通过免疫细胞化学分析了这些基因的蛋白质产物。在球囊损伤后15分钟内，c-fos、fosB、c-jun、junB和junD的mRNA水平升高了几倍。相比之下，fos相关抗原（fra-1）mRNA的表达开始延迟。这些即刻早期基因的表达动力学与经生长因子刺激而增殖的培养细胞中的相似，这表明体内这种SMC基因激活反映了血液来源的生长因子渗透到血管壁或预先形成的生长因子的血管内释放。在用抗Fos和Jun蛋白的抗血清处理球囊损伤后2小时，证明了fos和jun基因翻译成免疫反应性产物。用环己酰亚胺处理大鼠消除了这种免疫反应性。Fos和Jun产物的分布集中在大鼠主动脉腔缘的SMC细胞核中。这种局灶性表达可能对血管损伤后SMC DNA合成和迁移的启动产生影响。此外，血管球囊损伤后SMC中Fos和Jun蛋白的表达可作为各种实验条件下SMC激活的指标。
