发育阶段M-CAT结合因子的组织分布及表达动力学

采用胶阻滞和DNA-蛋白质印迹技术分析了鸡胚和雏鸡发育不同阶段骨骼肌、心肌、胗、肝和脑组织核抽提物中M-CAT结合因子(MCBF)与含CATTCCT、CATTGCT核心序列的寡核苷酸的相互作用.胶阻滞实验结果表明，被检的五种组织均有MCBF结合活性存在，但结合模样不完全相同；两寡核苷酸探针与同一骨骼肌核抽提物结合模样也不相同.采用两寡核苷酸为探针对五种组织核抽提物进行DNA-蛋白质印迹分析均检出一分子质量约30 ku 核因子，提示30 ku核因子是存在于五种组织中的普遍因子，该因子可直接或以同二/多聚体结合CATTCCT、CATTGCT序列，属MCBF结合活性的基本组成成分.除普遍因子外，胶阻滞分析结果不排除各组织存在的特异因子通过蛋白质-蛋白质相互作用、与30 ku因子形成杂聚体结合DNA的可能性.骨骼肌组织30 ku因子在胚胎发育18天前表达，出生后消失.

Tissue Distribution and Expression Dynamics of M-CAT Binding Factor During Chicken Development

The interactions between M-CAT binding factors (MCBFs) in nuclear extracts from developing chick tissues with oligonucleotides containing CATTCCT or CATTGCT core sequence were analyzed by gel retardation and Southwestern blot. Gel retardation assays showed that binding activities of MCBFs expressed in all tested organs, including skeletal muscle, cardiac muscle, gizzard, liver and brain, whereas the binding patterns were different between five tissues. Also, the binding patterns of CATTCCT and CATTGCT core sequence-containing oligonucleotides respectively with MCBFs in skeletal muscle extracts were different from each other. Southwestern blot analysis indicated that a 30 ku MCBF existed in the extracts from five tissues of chicken embryos by using oligonucleotides containing either CATTCCT or CATTGCT core sequence as a probe, suggesting that 30 ku molecule is an ubiquitous factor expressed in all tissues and this molecule can bind to both oligonucleotides in the manner of monomer or/and dimer and polymer. These imply that 30 ku molecule is essential for MCBF binding activities. Besides the ubiquitous factor, the possibility of specific factor(s) interacting with 30 ku molecule to form a heterodimer to bind to DNA can not be excluded. The ubiquitous factor of 30 ku expressed in skeletal muscle during embryonic development and disappeared after birth.