Sequence Variants Impacting Cardiomyocyte S-phase Activity in Inbred Mice Following Injury

序列变异影响近交小鼠损伤后心肌细胞 S 期活性

• 批准号: 10550204
• 负责人: LOREN J FIELD
• 金额: $ 50.44万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-02-15 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10550204
• 关键词: Abbreviations; Adult; Alleles; Anatomy; Animals; Apoptosis; Backcrossings; Bromodeoxyuridine; Candidate Disease Gene; Cardiac; Cardiac Myocytes; Cell Cycle; Cell Cycle Progression; Chromosome 3; Congenic Mice; Distal; Echocardiography; Exhibits; Genes; Genetic; Genetically Modified Animals; Heart; Heart Injuries; Heterozygote; Hypertrophy; Image Analysis; Inbred DBA Mice; Inbred Mouse; Inbred Strains Mice; Infarction; Infusion procedures; Injury; Location; Measurement; Molecular Analysis; Monitor; Mouse Strains; Mus; Myocardial; Myocardial Infarction; Natural regeneration; Nucleotides; Pattern; Phenotype; Reporter; S phase; Structure; System; Systems Analysis; Testing; Time; Transgenes; Transgenic Organisms; Validation; Variant; Ventricular Remodeling; autosome; chromosomal location; coronary fibrosis; exome sequencing; experimental study; genetic testing; genetic variant; genome editing; heart function; hemodynamics; improved; insight; interest; myocardial injury; offspring; protein structure; regenerative growth; therapeutic development; therapeutic target; trait; transcriptome sequencing

Numerous studies have shown that induction of cardiomyocyte cell cycle activity can have a profound beneficial impact on cardiac structure and function following myocardial infarction. It has also been shown that genetic background can impact the intrinsic rate of cardiomyocyte cell cycle activity in mice. We have observed that mice in a DBA/2J genetic background (abbreviated DBA) have very low levels of cardiomyocyte cell cycle activity following myocardial infarction. However, when crossed with C57Bl6/NCR mice (abbreviated NCR), the resulting (DBA x NCR)-F1 animals mice exhibit a marked increase in cardiomyocyte S-phase activity following infarction, indicating the presence of an autosomal gene (or genes) in the NCR background which acts in a dominant manner to facilitate cell cycle re-entry. Analysis of backcross mice established that this gene (or genes) resides in a region of interest (ROI) located on the distal end of chromosome 3. The experiments proposed in Aim 1 will test hypothesis that a single gene within the ROI is responsible for elevated cardiomyocyte S-phase activity post-infarction. Candidate genes within this region will be identified based on expression patterns observed in infarcted DBA vs. NCR hearts as well as by the presence of sequence variants predicted to impact protein structure and/or activity. The candidates will be systematically tested by generating genetically modified animals, subjecting them to myocardial infarction, and then monitoring the level of cardiomyocyte S-phase activity; an induction of cardiomyocyte cell cycle activity would confirm that the candidate gene being tested is responsible for the trait. The experiments proposed in Aim 2 will test the hypothesis that the elevated cell cycle activity encoded by the NCR ROI alleles has a positive impact on the diminished cardiac function and adverse myocardial remodeling which is encountered post-infarction. Congenic mice in a DBA genetic background which retain heterozygosity on the distal end of chromosome 3 and thus carry the NCR allele (or alleles) which is a major contributor to cardiomyocyte S-phase induction will be generated. The mice will then be subjected to myocardial infarction and longitudinal functional analysis. Terminal analyses will include comprehensive hemodynamic measurements as well as assessment of adverse remodeling (cardiomyocyte apoptosis, hypertrophy and myocardial fibrosis); relative improvements in cardiac function and structure would indicate a beneficial effect from the NCR-encoded cell cycle activity following myocardial injury. Ultimately, the identification and validation of genes underlying intrinsic differences in cardiomyocyte cell cycle rates observed in different strains of mice could suggest potential therapeutic targets with which to enhance regenerative growth in injured hearts.

大量研究表明，诱导心肌细胞周期活动可产生深远的影响 对心肌梗死后心脏结构和功能的有益影响。它还表明， 遗传背景可以影响小鼠心肌细胞周期活动的内在率。我们观察到 具有DBA/2J遗传背景(简称DBA)的小鼠的心肌细胞周期水平非常低 心肌梗死后的活动。然而，当与C57BL6/NCR小鼠(简称NCR)杂交时， 结果(DBAxNcr)-F1小鼠表现出明显的心肌细胞S时相活动增加 脑梗塞，表明在NCR背景中存在一个或多个常染色体基因，该基因在 以显性方式促进细胞周期重新进入。对回交小鼠的分析证实，这个基因(或多个基因) 位于3号染色体远端的感兴趣区(ROI)。 目标1将检验假设，即在感兴趣区内的单个基因负责心肌细胞S时相升高 脑梗塞后的活动情况。该区域内的候选基因将根据表达模式进行识别 在梗死的DBA和NCR心脏中观察到，以及通过预测影响 蛋白质结构和/或活性。候选人将通过产生转基因产品进行系统测试 动物，造成心肌梗死，然后监测心肌细胞S时相的水平 活性；心肌细胞周期活性的诱导将证实正在测试的候选基因是 对这一特征负有责任。目标2中提出的实验将检验这样一个假设，即细胞周期升高 NCR ROI等位基因编码的活动对心功能减弱有积极影响，对心脏功能不利 心肌梗死后遇到的心肌重塑。具有DBA遗传背景的同源小鼠 保持3号染色体远端的杂合性，从而携带NCR等位基因，这是一种 心肌细胞S时相诱导将产生主要贡献者。然后，这些老鼠将受到 心肌梗死与纵向功能分析。终端分析将包括全面的 血流动力学测量以及不良重构的评估(心肌细胞凋亡， 肥大和心肌纤维化)；心脏功能和结构的相对改善将表明 心肌损伤后NCR编码的细胞周期活动的有益影响。归根结底，身份 以及对不同类型心肌细胞周期频率内在差异的基因的验证 小鼠品系可以提供潜在的治疗靶点，用来促进损伤后的再生生长 红心。