Allen R T, Hunter W J, Agrawal D K
Department of Internal Medicine, Creighton University School of Medicine, Omaha, Nebraska 68178, USA.
Scanning. 1998 Nov;20(8):577-86. doi: 10.1002/sca.4950200806.
Apoptosis is a physiologic form of cell death present in many disease conditions. When the balance of mitosis versus apoptosis is altered, tumor-like growth or degeneration of tissues may ensue. This appears to occur in several diseases, including those of the cardiovascular system, where apoptosis plays a key role in atherosclerosis and restenosis following angioplasty. Since c-myc is upregulated in the pathogenesis of these diseases, we chose to study the sequential morphologic features of programmed cell death in vascular smooth muscle cells induced by c-myc and by the adenovirus early gene E1A. Morphology and timed events in apoptotic cell cultures were analyzed by scanning electron microscopy, transmission electron microscopy, and time-lapse videomicroscopy. We observed that both c-myc- and E1A-induced apoptosis (in serum-free medium) resulted in numerous, tightly packed clusters of apoptotic blebs, as well as in one or two asymmetrically larger blebs. Transmission electron miscroscopy analysis revealed the larger blebs contained mostly nuclear chromatin, whereas the many smaller fragments often had little or no chromatin. Time-lapse studies showed that apoptosis was induced at a slower rate in cells stably transfected with c-myc versus those stably transfected with E1A. The early changes of apoptosis, including cell shrinkage and intense blebbing, occurred in under 5 min in both cells. Slight alterations such as cell size and further rounding occurred up to 8 h following the initial changes of apoptosis. Rather than being a part of the apoptotic response, release from the culture floor almost entirely resulted from movement of the culture flask. These studies provide a framework of timed morphologic events for future mechanistic investigation into the key aspects of myc- and E1A-induced apoptosis in vascular smooth muscle.
细胞凋亡是一种存在于多种疾病状态下的生理性细胞死亡形式。当有丝分裂与细胞凋亡之间的平衡被打破时，可能会导致肿瘤样生长或组织退化。这似乎在几种疾病中都会发生，包括心血管系统疾病，在动脉粥样硬化和血管成形术后再狭窄中，细胞凋亡起着关键作用。由于c-myc在这些疾病的发病机制中上调，我们选择研究由c-myc和腺病毒早期基因E1A诱导的血管平滑肌细胞程序性细胞死亡的连续形态学特征。通过扫描电子显微镜、透射电子显微镜和延时视频显微镜分析凋亡细胞培养物中的形态和定时事件。我们观察到，c-myc和E1A诱导的凋亡（在无血清培养基中）均导致大量紧密堆积的凋亡小泡簇，以及一两个不对称的较大小泡。透射电子显微镜分析显示，较大的小泡主要包含核染色质，而许多较小的碎片通常几乎没有染色质或没有染色质。延时研究表明，与稳定转染E1A的细胞相比，稳定转染c-myc的细胞凋亡诱导速率较慢。凋亡的早期变化，包括细胞收缩和强烈的小泡形成，在两种细胞中均在5分钟内发生。在凋亡的初始变化后长达8小时内，会出现如细胞大小和进一步变圆等轻微变化。细胞从培养皿底部脱离几乎完全是由于培养瓶的移动，而不是凋亡反应的一部分。这些研究为未来对myc和E1A诱导的血管平滑肌细胞凋亡关键方面的机制研究提供了一个定时形态学事件框架。
