Mastronardi F G, Mak B, Ackerley C A, Roots B I, Moscarello M A
Department of Biochemistry, Hospital for Sick Children, Toronto, Canada.
J Clin Invest. 1996 Jan 15;97(2):349-58. doi: 10.1172/JCI118422.
Transgenic mice containing different numbers of transgenes (2-70) of the myelin proteolipid protein DM20 were phenotypically normal up to 3 mo of age, after which the mice containing 70 copies of the transgene spontaneously demyelinated and died at 10-12 mo. Since we demonstrated that demyelination in multiple sclerosis involved specific chemical changes in myelin basic protein (MBP), we investigated the MBP in our transgenic line for similar changes. Both the total amount of MBP in brain and the MBP mRNA levels were unaffected at the different ages. All the isoforms (14-21 kD) of MBP were present, but the microheterogeneity (a posttranslational event) was changed resulting in a higher proportion of the less cationic components reminiscent of the changes in MBP found in multiple sclerosis. An increased amount of the citrullinated form of MBP was found by Western blot analysis. Immunogold labeling of cryosections of brain revealed a greater density of particles with the anticitrulline antibody at 10 mo and that the levels of peptidylarginine deiminase (which deiminates protein-bound arginine to citrulline) were increased. This stable transgenic line represents a useful animal model for the human disease multiple sclerosis.
含有不同数量（2 - 70个）髓磷脂蛋白脂蛋白DM20转基因的小鼠，在3月龄前表型正常，之后，含有70个转基因拷贝的小鼠会自发脱髓鞘，并在10 - 12月龄时死亡。由于我们证明多发性硬化症中的脱髓鞘涉及髓磷脂碱性蛋白（MBP）的特定化学变化，因此我们研究了我们转基因品系中的MBP是否有类似变化。在不同年龄时，脑中MBP的总量和MBP mRNA水平均未受影响。MBP的所有同工型（14 - 21 kD）均存在，但微异质性（一种翻译后事件）发生了变化，导致阳离子性较低的组分比例更高，这让人联想到在多发性硬化症中发现的MBP变化。通过蛋白质免疫印迹分析发现，MBP瓜氨酸化形式的量增加。脑冰冻切片的免疫金标记显示，在10月龄时，抗瓜氨酸抗体的颗粒密度更高，并且肽基精氨酸脱亚氨酶（将与蛋白质结合的精氨酸脱亚氨生成瓜氨酸）的水平升高。这个稳定的转基因品系代表了一种用于人类疾病多发性硬化症的有用动物模型。
