Matsuura Ken, Mohamed Haytham M A, Youssef Mohieldin M M, Yoshida Yutaka, Yamamoto Tadashi
Cell Signal Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son 904-0495, Japan.
Neural Circuit Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son 904-0495, Japan.
iScience. 2022 Jun 30;25(8):104692. doi: 10.1016/j.isci.2022.104692. eCollection 2022 Aug 19.
The CaMKΙΙα-Cre mouse lines, possibly the most used Cre lines in neuroscience, have resulted in over 800 articles to date. Here, we demonstrate that the second most widely used CaMKΙΙα-Cre line, Tg(Camk2a-cre)2Gsc (or CamiCre), shows ectopic overexpression of synaptotagmin 2, the most efficient Ca sensor for fast synchronous neurotransmitter release, in excitatory presynapses of Cre brains. Moreover, the upregulation of immediate-early genes and genes incorporated in bacterial artificial chromosome (BAC) transgenes, such as L-proline transporter , was found in Cre hippocampus. The copy number and integration site of the transgene are suggested to have caused the aberrant gene expression in Cre brains. Most importantly, CamiCre mice showed functional phenotypes, such as hyperactivity and enhanced associative learning, suggesting that neural activities are affected. These unexpected results suggest difficulties in interpreting results from studies using the CamiCre line and raise a warning of potential pitfalls in using Cre driver lines in general.
CaMKΙΙα-Cre小鼠品系可能是神经科学领域使用最广泛的Cre品系，迄今为止已发表了800多篇相关文章。在此，我们证明，第二广泛使用的CaMKΙΙα-Cre品系Tg(Camk2a-cre)2Gsc（或CamiCre）在Cre脑的兴奋性突触前膜中显示出突触结合蛋白2的异位过表达，突触结合蛋白2是快速同步神经递质释放最有效的钙传感器。此外，在Cre海马体中发现了立即早期基因以及细菌人工染色体（BAC）转基因中包含的基因（如L-脯氨酸转运体）的上调。转基因的拷贝数和整合位点被认为导致了Cre脑中异常的基因表达。最重要的是，CamiCre小鼠表现出功能表型，如多动和增强的联想学习能力，这表明神经活动受到了影响。这些意外结果表明在解释使用CamiCre品系的研究结果时存在困难，并总体上对使用Cre驱动品系的潜在陷阱发出了警告。
