Chemokines in healing myocardial infarction

摘要： TGF-β 1超家族成员在梗死心脏的重塑中起着重要作用，调节心肌细胞的凋亡。 参与心肌炎症、修复和纤维化的所有细胞类型的表型和功能。转化生长因子 Smads通过激活涉及受体激活Smads（R-Smads）的分子级联发挥作用，或 通过Smad独立机制。然而，有效的修复需要TGF-β 1的严格调节， 行动，以防止导致适应不良的心脏重塑的不良后果。 过度活跃或延长的TGF-β信号传导可以促进心肌细胞、成纤维细胞和巨噬细胞 活化，刺激持续的纤维化、肥大和吞噬反应。内生 在组织修复、重塑和修复中负调节TGF-β 1反应的机制 纤维化仍然未知。 目前的建议探讨了负责抑制的分子机制， 在梗死和重塑心肌中TGF-β超家族信号传导的终止。我们 未发表的初步数据表明，在负调控中， TGF-β 1超家族信号转导的研究。首先，细胞特异性诱导抑制性Smads（I-Smads）， Smad 7和Smad 6可负性调节心肌损伤后TGF-β 1和BMP的反应 梗塞第二，TGF-β信号传导可能通过细胞特异性的调节在受体水平上被调节。 诱导跨膜假受体BAMBI（BMP和激活素膜结合的 抑制剂），其缺乏细胞内激酶结构域，并至少部分抑制TGF-β信号传导， 通过与I-Smads的互动。细胞特异性负调控机制的作用 将在4个具体目标中探索TGF-β 1的表达： 具体目的1：研究Smad 7在心肌细胞、成纤维细胞、成纤维细胞中的作用 和巨噬细胞表型。我们的初步研究表明，Smad 7是 在边界区心肌细胞，和梗死肌成纤维细胞和巨噬细胞中显著上调， 并且Smad 7敲低或过表达调节TGF-β 1驱动的细胞应答。因此，委员会认为， 我们将使用心肌细胞、成纤维细胞/肌成纤维细胞和骨髓细胞特异性Smad 7敲除小鼠， 最近由我们实验室产生，以探索Smad 7对梗死心脏的细胞作用。 具体目标2：剖析造成下列影响的分子机制： Smad 7在体内和体外。Smad 7的作用可能涉及抑制Smad依赖性或非依赖性的 Smad途径，并可能涉及与T细胞受体，R-Smads或TGF-β-独立信号的相互作用。我们 在心脏成纤维细胞中的初步研究表明，Smad 7抑制Smad 2/3活化， 影响T细胞受体的磷酸化。Smad 7依赖性调节细胞凋亡的分子机制 心肌细胞、成纤维细胞和巨噬细胞表型将在体外和体内进行研究， 功能丧失和功能获得方法。 具体目标3：研究Smad 6在梗死灶修复和重塑中的作用。 心我们的初步研究表明Smad 6在心肌细胞、成纤维细胞和巨噬细胞中的诱导作用 浸润愈合的梗死，并证明成纤维细胞Smad 6发挥的作用不同于 Smad 7介导的效应。将产生条件性Smad 6敲除小鼠以解剖细胞- Smad 6在心肌梗死和重构中的特异性作用及其机制 负责Smad 6介导的影响将在体内和体外探索。 具体目标4：研究BAMBI在调节TGF-β 1应答中的作用。 梗死和重塑心脏。我们的初步研究表明，BAMBI在梗死灶中表达上调， 肌成纤维细胞和巨噬细胞。因此，我们将使用成纤维细胞和巨噬细胞特异性BAMBI 敲除和体外实验，以研究BAMBI在调节细胞特异性TGF-β 1中的作用。 在梗塞的心脏中的收缩。此外，我们将探讨BAMBI和I之间的相互作用- 斯麦兹 拟议的研究将提供第一个系统的调查机制 负责组织损伤模型中TGF-β 1负调节。

ABSTRACT: TGF- superfamily members play a central role in remodeling of the infarcted heart, modulating phenotype and function of all cell types involved in myocardial inflammation, repair, and fibrosis. TGF- s function by activating molecular cascades involving Receptor-activated Smads (R-Smads), or through Smad-independent mechanisms. However, effective repair requires tight regulation of TGF- actions, in order to prevent adverse consequences that lead to maladaptive cardiac remodeling. Overactive, or prolonged TGF- signaling can promote cardiomyocyte, fibroblast and macrophage activation, stimulating persistent fibrotic, hypertrophic and phagocytic responses. The endogenous mechanisms responsible for negative regulation of TGF- responses in tissue repair, remodeling and fibrosis remain unknown. The current proposal explores the molecular mechanisms responsible for suppression and termination of TGF- superfamily signaling in the infarcted and remodeling myocardium. Our unpublished preliminary data suggest an important role for 2 distinct mechanisms in negative regulation of TGF- superfamily signaling. First, cell-specific induction of the inhibitory Smads (I-Smads), Smad7 and Smad6 may negatively regulate TGF- and BMP responses following myocardial infarction. Second, TGF- signaling may be regulated at the receptor level through cell-specific induction of the transmembrane pseudoreceptor BAMBI (BMP and activin membrane-bound inhibitor), which lacks an intracellular kinase domain, and inhibits TGF- signaling, at least in part, through interactions with I-Smads. The role of the cell-specific mechanisms for negative regulation of TGF- will be explored in 4 specific aims: Specific aim 1: to investigate the role of Smad7 in regulation of cardiomyocyte, fibroblast and macrophage phenotype following infarction. Our preliminary studies show that Smad7 is markedly upregulated in border zone cardiomyocytes, and in infarct myofibroblasts and macrophages, and that Smad7 knockdown or overexpression modulate TGF--driven cellular responses. Accordingly, we will use cardiomyocyte-, fibroblast/myofibroblast- and myeloid cell-specific Smad7 knockout mice, recently generated by our laboratory to explore the cellular effects of Smad7 on the infarcted heart. Specific aim 2: to dissect the molecular mechanisms responsible for the effects of Smad7 in vivo and in vitro. Smad7 actions may involve suppression of Smad-dependent or non- Smad pathways and may involve interactions with TRs, R-Smads or TGF--independent signals. Our preliminary studies in cardiac fibroblasts suggest that Smad7 restrains Smad2/3 activation without affecting phosphorylation of TRs. The molecular mechanisms for Smad7-dependent regulation of cardiomyocyte, fibroblast and macrophage phenotype will be studied in vitro and in vivo, using both loss and gain-of-function approaches. Specific aim 3: to investigate the role of Smad6 in repair and remodeling of the infarcted heart. Our preliminary studies show Smad6 induction in cardiomyocytes, fibroblasts, and macrophages infiltrating the healing infarct, and demonstrate that fibroblast Smad6 exerts actions distinct from Smad7-mediated effects. Conditional Smad6 knockout mice will be generated to dissect the cell- specific actions of Smad6 in the infarcted and remodeling myocardium, and the mechanisms responsible for Smad6-mediated effects will be explored in vivo and in vitro. Specific aim 4: to study the role of BAMBI in regulation of TGF- responses in the infarcted and remodeling heart. Our preliminary studies show that BAMBI is upregulated in infarct myofibroblasts and macrophages. Accordingly, we will use fibroblast- and macrophage-specific BAMBI knockouts and in vitro experiments, in order to study the role of BAMBI in modulating cell-specific TGF-  actions in the infarcted heart. Moreover, we will explore interactions between BAMBI and the I- Smads. The proposed studies will provide the first systematic investigation of the mechanisms responsible for negative regulation of TGF- in a model of tissue injury.