Dong Kunzhe, Bai Zhixia, He Xiangqin, Zhang Lu, Hu Guoqing, Yao Yali, Cai Chen-Leng, Zhou Jiliang
Immunology Center of Georgia, Augusta University, Augusta, GA 30912, USA; Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA; Department of Anesthesiology and Perioperative Medicine, General Hospital of Ningxia Medical University, Yinchuan, Ningxia 750001, China.
J Mol Cell Cardiol. 2025 May;202:144-152. doi: 10.1016/j.yjmcc.2025.03.010. Epub 2025 Mar 21.
Dysfunction in either embryonic or postnatal smooth muscle cells (SMCs) significantly contributes to the progression of various cardiovascular and visceral diseases. Therefore, elucidating the molecular mechanisms governing SMC development and homeostasis is crucial. MYH11 is the most reliable lineage gene for SMCs and has been utilized to develop tamoxifen-inducible Cre driver lines for achieving SMC-specific gene manipulation by crossing with mice carrying the loxP-flanked gene, particularly in adult mice. For studies involving SMCs during embryogenesis, the commonly used constitutive Cre driver is controlled by the Tagln (also known as SM22α) promoter. However, this Cre driver exhibits activity in multiple non-SMC populations, including cardiomyocytes and skeletal muscle precursors, introducing confounding effects. Additionally, most existing SMC-specific Cre drivers are generated using a transgenic approach, raising concerns about random site integration and variable gene copy numbers. To address these limitations, we report a novel Cre mouse model generated by knock-in (KI) of a nuclear-localized Cre recombinase into the Myh11 gene locus using homologous recombination. We confirmed that the Cre activity precisely recapitulates endogenous Myh11 expression by crossing with Rosa26 mTmG or tdTomato reporter mice. Moreover, Myh11-driven Cre can efficiently delete the floxed allele of the transcription factor Tead1 specifically in SMCs. The Tead1 SMC-specific knockout mice did not exhibit an overt phenotype, thereby circumventing the embryonic lethal phenotype mediated by Tagln-driven Cre, as we previously reported. These findings establish this novel Cre driver line as a robust tool for tracing the Myh11-positive SMC lineage and manipulating gene function specifically in SMCs during embryonic development in both male and female mice.
胚胎期或出生后平滑肌细胞（SMC）功能障碍显著促进各种心血管和内脏疾病的进展。因此，阐明调控SMC发育和稳态的分子机制至关重要。MYH11是SMC最可靠的谱系基因，已被用于开发他莫昔芬诱导型Cre驱动系，通过与携带loxP侧翼基因的小鼠杂交来实现SMC特异性基因操作，特别是在成年小鼠中。对于涉及胚胎期SMC的研究，常用的组成型Cre驱动系由Tagln（也称为SM22α）启动子控制。然而，这种Cre驱动系在多个非SMC群体中表现出活性，包括心肌细胞和骨骼肌前体细胞，会产生混淆效应。此外，大多数现有的SMC特异性Cre驱动系是通过转基因方法产生的，这引发了对随机位点整合和可变基因拷贝数的担忧。为了解决这些局限性，我们报告了一种新型的Cre小鼠模型，该模型通过同源重组将核定位的Cre重组酶敲入Myh11基因座而产生。我们通过与Rosa26 mTmG或tdTomato报告基因小鼠杂交，证实了Cre活性精确重现了内源性Myh11表达。此外，Myh11驱动的Cre可以有效地在SMC中特异性删除转录因子Tead1的floxed等位基因。如我们之前所报道的，Tead1 SMC特异性敲除小鼠没有表现出明显的表型，从而避免了由Tagln驱动的Cre介导的胚胎致死表型。这些发现确立了这种新型Cre驱动系作为一种强大的工具，用于追踪Myh11阳性SMC谱系，并在雄性和雌性小鼠胚胎发育期间特异性地操纵SMC中的基因功能。
