Schnetzler B, Murakawa G, Abalos D, Halban P, Selden R
Laboratoires de Recherche Louis Jeantet, Centre Médical Universitaire, Geneva, Switzerland.
J Clin Invest. 1993 Jul;92(1):272-80. doi: 10.1172/JCI116561.
Insulin production was studied in transgenic mice expressing the human insulin gene under the control of its own promoter. Glucose homeostasis during a 48-h fast was similar in control and transgenic mice, with comparable levels of serum immunoreactive insulin. Northern blot and primer extension analyses indicated that more than twice as much insulin mRNA is present in pancreata from transgenic mice. Primer extension analysis using oligonucleotides specific for mouse insulins I and II or for human insulin, showed that the excess insulin mRNA was due solely to expression of the foreign, human insulin gene. The ratio of mRNA for mouse insulin I and II was unaffected by coexpression of human insulin. There were coordinate changes in the levels of all three mRNA during the 48-h fast, or after a 24-h fast followed by 24-h refeed. Despite the supraphysiologic levels of insulin mRNA in the transgenic mice, their pancreatic content of immunoreactive insulin was not significantly different from controls. The comparison of the relative levels of human and mouse insulin mRNAs with their peptide counterparts (separated by HPLC) indicates that the efficiency of insulin production from mouse insulin mRNA is greater than that from human, stressing the importance of posttranscriptional regulatory events in the overall maintenance of pancreatic insulin content.
在由自身启动子控制下表达人胰岛素基因的转基因小鼠中研究了胰岛素的产生。在48小时禁食期间，对照小鼠和转基因小鼠的葡萄糖稳态相似，血清免疫反应性胰岛素水平相当。Northern印迹和引物延伸分析表明，转基因小鼠胰腺中存在的胰岛素mRNA是对照小鼠的两倍多。使用对小鼠胰岛素I和II或人胰岛素特异的寡核苷酸进行引物延伸分析表明，过量的胰岛素mRNA完全是由于外源人胰岛素基因的表达。人胰岛素的共表达不影响小鼠胰岛素I和II的mRNA比例。在48小时禁食期间，或在24小时禁食后再喂食24小时后，所有三种mRNA的水平都有协同变化。尽管转基因小鼠中胰岛素mRNA水平超出生理水平，但其胰腺中免疫反应性胰岛素含量与对照小鼠并无显著差异。将人和小鼠胰岛素mRNA的相对水平与其肽对应物（通过HPLC分离）进行比较表明，小鼠胰岛素mRNA产生胰岛素的效率高于人胰岛素mRNA，这强调了转录后调控事件在胰腺胰岛素含量整体维持中的重要性。
