ANP Modulates Cardiac Remodeling via Cardiac Fibroblasts

ANP 通过心脏成纤维细胞调节心脏重塑

• 批准号: 7029290
• 负责人: Yiu-Fai Chen
• 金额: $ 36.38万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2009-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7029290
• 关键词: angiotensin II; atrial natriuretic peptide; biological signal transduction; cell proliferation; fibroblasts; gene targeting; heart cell; laboratory mouse; loss of heterozygosity; transforming growth factors

DESCRIPTION (provided by applicant): Atrial natriuretic peptide (ANP) is a well known component of the fetal gene program that is overexpressed in adult heart under stress conditions. Yet little attention has been devoted to the function of ANP in the stressed/hypertrophic heart. The current application will test the hypothesis that ANP has direct anti-growth and anti-fibrogenic effects that oppose the pro-fibrogenic actions of transforming growth factor (TGF)-beta and angiotensin II (ANGII), which are known to be overexpressed in heart under stress conditions, by interrupting their signaling cascades. We have shown that, compared to nontransgenic (NTG) controls, mice with homozygous disruption of the ANP gene (Nppa-/-) exhibit cardiac enlargement at baseline and exaggerated cardiac remodeling/fibrosis, as well as an early transition to failure, in response to transverse aortic constriction (TAC)-induced pressure overload stress. Preliminary studies revealed remarkable increases in myofibroblast transformation and expression of extracellular matrix (ECM) molecules in hearts of Nppa-/- mice subjected to TAG. We have also demonstrated that TAC-induced cardiac remodeling and fibrosis are abolished in mice that express an inducible dominant negative mutation of the TGF-beta receptor type II gene (DriTGFbRIl), and thus do not respond to TGF-beta signaling. Most recently, we have made the exciting preliminary observation that ANP signaling inhibits TGF-beta-induced nuclear translocation of phosphorylated-SmadS in mouse cardiac fibroblasts (CFs), defining for the first time a precise molecular mechanism by which ANP signaling may protect against cardiac remodeling/fibrosis and failure in response to hemodynamic stress. The Aims of this proposal are: 1) To establish the phenotypes of Nppa-/-, DnTGFbRII and control NTG mouse hearts under resting conditions and at various phases (acute stress, early compensatory stage of fibrosis and remodeling, and late decompensate/transition stage to failure) during pressure overload stress following TAG. This Aim will provide the first rigorous in vivo test of the role of TGF-beta signaling in mediating pressure overload-induced LV fibrosis/remodeling and of ANP in modulating these processes. 2) Using isolated CFs as an in vitro model, to define the intracellular signaling mechanisms leading to pro-fibrogenic/growth factor-stimulated CF proliferation/transformation and ECM expression. This Aim will provide a rigorous test of the hypothesis that ANP signaling has negative, and TGF-beta (and/or ANGII) signaling has positive stimulatory effects on these processes. ANP and/or components of its signaling pathway will be used to define the specific site(s) at which the ANP cascade intercepts pro-fibrogenic/growth factor signaling, thus inhibiting phenotypic transformation of CFs and ECM production. These mechanistic studies will provide a more rational basis for therapeutic intervention in patients with cardiac dysfunction/failure, many of whom have decreased levels of ANP.

描述（由申请人提供）：心房利钠肽（ANP）是胎儿基因程序的一个众所周知的组成部分，在应激条件下在成人心脏中过度表达。然而，很少有人关注ANP在应激/肥厚心脏中的作用。目前的应用将验证ANP具有直接的抗生长和抗纤维化作用的假设，通过阻断应激条件下心脏中过度表达的转化生长因子(TGF)- β和血管紧张素II （ANGII）的信号级联，来对抗促纤维化作用。我们已经证明，与非转基因（NTG）对照相比，ANP基因纯合子破坏（Nppa-/-）的小鼠在基线时表现出心脏增大，心脏重塑/纤维化加剧，以及对横断主动脉收缩（TAC）诱导的压力过载应激的早期过渡到衰竭。初步研究显示，TAG作用下Nppa-/-小鼠心肌成纤维细胞转化和细胞外基质（ECM）分子表达显著增加。我们还证明，在表达tgf - β受体II型基因（DriTGFbRIl）的可诱导显性负突变的小鼠中，tac诱导的心脏重构和纤维化被消除，因此对tgf - β信号传导没有反应。最近，我们进行了令人兴奋的初步观察，即ANP信号抑制tgf - β诱导的小鼠心脏成纤维细胞（CFs）中磷酸化smads的核易位，首次确定了ANP信号可能在血流动力学应激下保护心脏重构/纤维化和衰竭的精确分子机制。本研究的目的是：1)建立Nppa-/-、DnTGFbRII和控制NTG小鼠心脏在静睡条件下和TAG后压力过载应激的不同阶段（急性应激、纤维化和重构的早期代偿阶段和晚期失代偿/过渡到衰竭阶段）的表型。本研究将首次对tgf - β信号在介导压力过载诱导的左室纤维化/重构中的作用以及ANP在调节这些过程中的作用进行严格的体内试验。2)以分离的CF为体外模型，明确促纤维化/生长因子刺激CF增殖/转化和ECM表达的细胞内信号机制。本Aim将对ANP信号具有负性，而tgf - β（和/或ANGII）信号对这些过程具有正性刺激作用的假设进行严格检验。ANP和/或其信号通路的组成部分将用于确定ANP级联阻断促纤维化/生长因子信号传导的特定位点，从而抑制CFs和ECM产生的表型转化。这些机制研究将为心功能障碍/心力衰竭患者的治疗干预提供更合理的依据，其中许多患者的ANP水平降低。