Department of Microbiology, Immunology & Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, 40536, USA.
Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
Mamm Genome. 2019 Aug;30(7-8):226-236. doi: 10.1007/s00335-019-09811-6. Epub 2019 Jul 18.
BALB/cJ mice exhibit considerable phenotypic differences with other BALB/c substrains. Some of these traits involve the liver, including persistent postnatal expression of genes that are normally expressed only in the fetal liver and reduced expression of major urinary proteins. These traits are due to a mutation that dramatically reduces expression of the gene encoding the transcription factor Zinc fingers and homeoboxes 2 (Zhx2). BALB/cJ mice also exhibit reduced serum lipid levels and resistance to atherosclerosis compared to other mouse strains when placed on a high-fat diet. This trait is also due, at least in part, to the Zhx2 mutation. Microarray analysis identified many genes affecting lipid homeostasis, including Lipoprotein lipase, that are dysregulated in BALB/cJ liver. This led us to investigate whether hepatic lipid levels would be different between BALB/cJ and BALB/c mice when placed on a normal chow or a high-fat chow diet. On the high-fat chow, BALB/cJ mice had increased weight gain, increased liver:body weight ratio, elevated hepatic lipid accumulation and markers of liver damage when compared to BALB/c mice. These traits in BALB/cJ mice were only partially reversed by a hepatocyte-specific Zhx2 transgene. These data indicate that Zhx2 reduces liver lipid levels and is hepatoprotective in mice on a high-fat diet, but the partial rescue by the Zhx2 transgene suggests a contribution by both parenchymal and non-parenchymal cells. A model to account for the cardiovascular and liver phenotype in mice with reduced Zhx2 levels is provided.
BALB/cJ 小鼠与其他 BALB/c 亚系表现出相当大的表型差异。其中一些特征涉及肝脏,包括持续的出生后表达通常仅在胎儿肝脏中表达的基因,以及主要尿蛋白的表达减少。这些特征是由于一个突变导致编码转录因子锌指和同源盒 2(Zhx2)的基因表达显著降低。与其他小鼠品系相比,BALB/cJ 小鼠在高脂饮食下还表现出血清脂质水平降低和动脉粥样硬化抗性降低。这种特征至少部分也是由于 Zhx2 突变所致。微阵列分析确定了许多影响脂质稳态的基因,包括脂蛋白脂肪酶,它们在 BALB/cJ 肝脏中失调。这促使我们研究当 BALB/cJ 和 BALB/c 小鼠分别置于正常饲料或高脂饲料时,其肝脏脂质水平是否会有所不同。在高脂饲料中,与 BALB/c 小鼠相比,BALB/cJ 小鼠体重增加更多,肝脏与体重比增加,肝内脂质积累增加,肝损伤标志物升高。这些特征在 BALB/cJ 小鼠中仅部分被肝细胞特异性 Zhx2 转基因逆转。这些数据表明,Zhx2 降低了高脂肪饮食小鼠的肝脏脂质水平并具有肝保护作用,但 Zhx2 转基因的部分挽救表明实质细胞和非实质细胞都有贡献。提供了一种解释 Zhx2 水平降低的小鼠心血管和肝脏表型的模型。