Cardiomyocyte Differentiation Regulates Cardiac Function

心肌细胞分化调节心脏功能

• 批准号: 8045121
• 负责人: Mark A PERRELLA
• 金额: $ 41.59万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-12-02 至 2014-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8045121
• 关键词: Accounting; Actins; Adult; Affect; American; Appearance; Area; Birth; Cardiac; Cardiac Myocytes; Cardiovascular Diseases; Cause of Death; Cell Count; Cell Differentiation process; Cell Maturation; Cell physiology; Cells; Cessation of life; Chest; Commit; Cytoskeleton; Data; Defect; Development; Diagnosis; Dilated Cardiomyopathy; Disease; Embryo; Family; Family member; Functional disorder; Generations; Genes; Goals; Heart; Heart failure; Incidence; Injury; Investigation; Laboratories; Left atrial structure; Length; Mammals; Mus; Muscle Cells; Mutation; Myocardial; Myocardium; Myosin Light Chain Kinase; Natural regeneration; Neonatal Mortality; Newborn Infant; Organ; Pathway interactions; Phenotype; Process; Protein Family; Protein Isoforms; Protein-Serine-Threonine Kinases; RNA Splicing; Regulation; Research; Right atrial structure; Role; Signal Pathway; Site; Stem cells; Stress; Striated Muscles; Structure; Therapeutic; Thick; Tissues; Transmission Electron Microscopy; United States; base; cardiogenesis; cell type; constriction; experience; heart function; injured; injury and repair; insight; interest; member; mouse model; mutant; obscurin-MLCK; overexpression; postnatal; pressure; promoter; response; response to injury; stem

DESCRIPTION (provided by applicant): Different from many organs, the heart previously was felt to be a terminally differentiated, postmitotic organ. This led to the assumption that the heart contained a fixed number of cells postnatally, and that if injury led to myocyte death, the myocardium would need to maintain its functional role with a reduced number of cells. While striated muscle cells of cardiac origin undergo terminal differentiation shortly after birth in mammals, it has been shown that myocardial regeneration occurs following injury. This concept led to an interest in the potential of stem/progenitor cells in the heart. Endogenous cardiac progenitor cells (CPCs) are capable of limited myocardial regeneration at sites of injury, however the therapeutic potential of exogenously administered progenitor cells has been an intense area of investigation, as heart failure due to myocardial injury remains a difficult and deadly problem for millions of Americans. Thus, a major objective of this application is to further understand pathways responsible for the fate of CPCs (both during development and postnatally into adulthood), and to understand the ability of these progenitor cells to divide and differentiation into functional cardiomyocytes. Myosin light chain kinases (MLCK) are a family of proteins that are important for myocyte function. One member of this family is the striated preferentially expressed gene (Speg). The Speg locus generates four different gene isoforms, with Speg1 and Speg2 being expressed preferentially in striated muscle (including muscle of cardiac origin). Speg1 and Speg2 share homology with MLCK family members, and along with obscurin-MLCK, are unique members of the MLCK family as they contain two tandemly arranged serine/threonine kinase (MLCK) domains. Prior investigations in our laboratory revealed that Speg isoforms (particularly Speg1) are markers of striated muscle differentiation. However, the functional significance of Speg isoforms was yet to be elucidated. We disrupted the Speg gene locus in mice, and revealed that homozygous mutant (Speg-/-) hearts began to enlarge by 16.5 days post-coitum (dpc), and by 18.5 dpc showed a marked dilation of right and left atria and ventricles. These dilated Speg mutant hearts demonstrated poor function, and a phenotype consistent with a dilated cardiomyopathy. Speg-/- mice also experienced significant neonatal mortality. Interestingly, the hearts of Speg-/- mice showed a reduced number of cells per mm3 of tissue compared with Speg+/+ mice, and a less differentiated appearance by transmission electron microscopy (EM), suggesting an alteration in the development of cardiac parenchymal cells. The overall goal of the application is to elucidate the role of Speg in the fate and differentiation of CPCs into functional cardiomyocytes, and to ascertain the importance of Speg in cardiac injury, repair, and function. To achieve this goal, we propose the following Aims: 1) investigate the role of Speg in CPC fate, commitment to the cardiomyocyte lineage, and cardiomyocyte differentiation; 2) decipher the mechanisms responsible for the development of cardiac dysfunction in the absence of Speg; & 3) determine the importance of Speg during cardiac injury (pressure overload) in adult mice. PUBLIC HEALTH RELEVANCE: Cardiovascular diseases have been the leading cause of death in the United States for more than 80 years, recently accounting for 35.3% of all deaths in the United States. Heart failure is a very prevalent disease process that contributes to deaths associated with cardiovascular diseases, and the incidence of heart failure remains extremely high with 670,000 new cases diagnosed in the United States in 2006. This application will provide new insight into the differentiation and maturation of cardiac muscle cells, and determine the importance of this differentiation process on overall heart function in newborn and adult hearts that have been injured.

描述（由申请人提供）：与许多器官不同，以前的心脏被认为是最终分化的有丝分裂后器官。这导致了以下假设，即心脏在产后含有固定数量的细胞，并且如果损伤导致心肌细胞死亡，则心肌将需要保持其功能作用，而细胞数量减少。尽管哺乳动物出生后不久，心脏来源的横纹肌肉会经历末端分化，但已显示在损伤后发生心肌再生。这个概念引起了对心脏中茎/祖细胞潜力的兴趣。内源性心脏祖细胞（CPC）能够在损伤部位的心肌再生有限，但是由于心肌损伤导致的心力衰竭仍然是数百万美国人的困难和致命的问题，因此外源给药的祖细胞的治疗潜力一直是一个严格的研究领域。因此，本应用的主要目的是进一步了解负责CPC（在发育期间和产后到成年期）命运的途径，并了解这些祖细胞分裂和分化为功能性心肌细胞的能力。肌球蛋白轻链激酶（MLCK）是对肌细胞功能很重要的蛋白质家族。该家族的一位成员是横纹型的优先表达基因（SPEG）。 SPEG基因座产生四个不同的基因同工型，SPEG1和SPEG2在横纹肌肉中优先表达（包括心脏起源的肌肉）。 SPEG1和SPEG2与MLCK家族成员以及Miskurin-MLCK共享同源性，因为它们包含两个串联布置的丝氨酸/苏氨酸激酶（MLCK）领域，因此是MLCK家族的独特成员。我们实验室的先前研究表明，SPEG同工型（尤其是SPEG1）是条纹肌肉分化的标志。但是，SPEG同工型的功能意义尚未阐明。我们破坏了小鼠的SPEG基因基因座，并揭示了纯合突变体（SPEG - / - ）的心脏开始增大，后涂层后16.5天（DPC），到18.5 DPC显示出明显的右膨胀，左，左心室和心室。这些扩张的Speg突变心脏表现出功能不佳，并且与扩张的心肌病一致的表型。 SPEG - / - 小鼠还经历了明显的新生儿死亡率。有趣的是，与SPEG+/+小鼠相比，SPEG - / - 小鼠的心脏显示每MM3组织的细胞数量减少，而通过透射电子显微镜（EM）的外观较少，表明心脏实质细胞的发展发生了变化。该应用的总体目标是阐明SPEG在CPC在功能性心肌细胞中的命运和分化中的作用，并确定SPEG在心脏损伤，修复和功能中的重要性。为了实现这一目标，我们提出以下目的：1）研究SPEG在CPC命运中的作用，对心肌细胞谱系的承诺和心肌细胞分化； 2）破译在没有SPEG的情况下导致心脏功能障碍发展的机制； ＆3）确定成年小鼠心脏损伤期间SPEG的重要性。 公共卫生相关性：80多年来，心血管疾病一直是美国的主要死亡原因，最近占美国所有死亡人数的35.3％。心力衰竭是一个非常普遍的疾病过程，导致与心血管疾病相关的死亡，心力衰竭的发生率仍然很高，在2006年在美国诊断出的67万例新病例。该应用将提供对心脏肌肉细胞的差异和成熟的新见解，并确定对这种差异化的心脏对新生儿和成人心脏功能的重要性。