Murphy L J, Molnar P, Lu X, Huang H
Department of Internal Medicine, University of Manitoba, Winnipeg, Canada.
J Mol Endocrinol. 1995 Dec;15(3):293-303. doi: 10.1677/jme.0.0150293.
Transgenic mice which expressed human IGF-binding protein-3 (hIGFBP-3) were generated by pronuclear injection of an hIGFBP-3 cDNA driven by the mouse metallothionein 1 promoter. Two of the seven founder mice had measurable levels of hIGFBP-3 in the circulation. The serum levels of hIGFBP-3 increased as the mice were bred to homozygosity and were further induced by supplementing the drinking water with 25 mM ZnCl2. While the birth weight, litter size and body weight of transgenic mice were not significantly different from non-transgenic litter mates or wild-type mice derived from the same genetic background, the transgenic mice demonstrated selective organomegaly. The spleen, liver and heart of mice derived from both founders were significantly heavier compared with organs from non-transgenic mice (P < 0.05, P < 0.005 and P < 0.01 respectively). The weights of the brain and kidney were similar in transgenic and non-transgenic mice. Expression of the transgene was detected in the kidney, small intestine and colon by Northern blot analysis. Western ligand blotting of serum from transgenic mice did not demonstrate any change in the abundance of the IGFBPs detected by this method. When serum from transgenic mice was incubated with 125I-labeled IGF-I and analyzed by Sephacryl S-200 chromatography under neutral conditions a significantly (P < 0.05) increased amount of the radioactivity was found in the 140 kDa ternary complex compared with serum from wild-type mice. Immunoreactive hIGFBP-3 was detected in the 140 kDa ternary complex but the majority of immunoreactive hIGFBP-3 present in transgenic mouse serum eluted in later fractions indicating that it was not associated with the acid-labile subunit. These data demonstrate that modest constitutive expression of hIGFBP-3 has a selective effect on organ growth and development. The establishment of these IGFBP-3 transgenic mouse strains may provide useful models to investigate further the physiological role of IGFBP-3.
通过原核注射由小鼠金属硫蛋白1启动子驱动的hIGFBP - 3 cDNA，培育出了表达人胰岛素样生长因子结合蛋白3（hIGFBP - 3）的转基因小鼠。7只奠基小鼠中有2只循环系统中hIGFBP - 3水平可测。随着小鼠繁殖至纯合状态，血清中hIGFBP - 3水平升高，并且通过在饮用水中补充25 mM ZnCl2进一步诱导升高。虽然转基因小鼠的出生体重、窝仔数和体重与同窝非转基因小鼠或来自相同遗传背景的野生型小鼠相比无显著差异，但转基因小鼠表现出选择性器官肿大。来自两个奠基小鼠品系的小鼠的脾脏、肝脏和心脏比非转基因小鼠的相应器官明显更重（P < 0.05、P < 0.005和P < 0.05）。转基因小鼠和非转基因小鼠的脑和肾重量相似。通过Northern印迹分析在肾、小肠和结肠中检测到转基因的表达。对转基因小鼠血清进行的Western配体印迹分析未显示该方法检测到的IGFBPs丰度有任何变化。当将转基因小鼠血清与125I标记的IGF - I孵育，并在中性条件下通过Sephacryl S - 200色谱分析时，与野生型小鼠血清相比，在140 kDa三元复合物中发现放射性显著（P < 0.05）增加。在140 kDa三元复合物中检测到免疫反应性hIGFBP - 3，但转基因小鼠血清中存在的大多数免疫反应性hIGFBP - 3在较晚的级分中洗脱，表明它与酸不稳定亚基不相关。这些数据表明，hIGFBP - 3适度的组成型表达对器官生长和发育具有选择性作用。这些IGFBP - 3转基因小鼠品系的建立可能为进一步研究IGFBP - 3的生理作用提供有用的模型。
