心脏组织特异性表达Neuregulin-2转基因小鼠的建立及心脏功能分析

The establishment of cardiac-specific human Neuregulin-2 transgenic mice and cardiacfunction analysis

目的神经调节蛋白2(neuregulin-2,NRG2)可促进神经系统发育,基因缺失表现早期生长延迟,NRG2在心脏中也有表达,但其在心脏发育尤其是病理刺激时对心脏结构及功能的影响尚未见报道。本文目的是建立心脏组织特异性表达NRG2转基因小鼠,分析其在正常及压力负荷刺激时对心脏结构及功能的影响。方法将人NRG2基因插入到心脏特异性启动子α-MHC下游,构建转基因表达载体,显微注射法建立NRG2转基因小鼠,PCR鉴定转基因小鼠基因型,western blot鉴定NRG2蛋白在心脏中的表达并筛选高表达的转基因品系,主动脉缩窄术(transverse aortic constriction,TAC)制备压力负荷诱导的心肌肥厚小鼠模型。利用超声影像分析和病理学观察小鼠心脏结构和功能改变。结果建立了心脏组织特异性高表达NRG2转基因小鼠品系。与同窝阴性转基因小鼠相比,转基因小鼠左心室舒张末期后壁厚度(LVPWD)明显增加,3月龄时可达15.6%(P<0.05),经压力负荷刺激后,NRG2转基因手术小鼠心室壁增厚程度显著下降,心室腔增大,同时心肌排列紊乱程度和纤维化程度明显比NTG手术小鼠严重。结论在压力负荷下,转基因表达NRG2缩短了肥厚过程,同时加速了心衰进程。

Objective To study the effects of NRG2 on cardiac structure and function , we established the cardiac-specific human NRG2 transgenic mice and investigate the effect of NRG2 on cardiac structure and function under pressure overload situation .Methods The transgenic vector was constructed by insertion of the human NRG2 gene under the α-MHC promoter.The transgenic mice were generated by microinjection and were all maintained on a C57BL/6J genetic background .The genotype of transgenic mice was identified by PCR and the expression level of target gene was＆amp;nbsp;determined by western blot .Transverse aortic constriction （ TAC） was applied to prepare the pressure overload induced cardiomyopathy mice model .The cardiac structure and function of the transgenic mice were compared and analysized by echocardiographic and pathological observation .Results Transgenic mice with high level of NRG2 in heart tissues were established.The left ventricular wall thickness （LVPWD） was increased, and to 15.6% at 3 months old compared with that of the non transgenic （ NTG） mice.The hypertrophy of left ventricular wall caused by pressure overload was removed due to the expression of NRG2 .Meanwhile, cardiac disarray and fibrosis were increased obviously compared with that of the NTG mice.Conclusion The transgenic expression of NRG2 in heart tissues could shorten the pathological process of hypertrophy, but accelerated the process of heart failure （HF）.