Duplin: A Novel A-Kinase Anchoring Protein

描述(申请人提供)：心脏损伤后，心肌经历适应性变化，包括肥大、收缩能力改变和信号改变。这种心脏重塑的过程最终会导致心力衰竭(HF)，据估计，2%的美国人会受到影响，随着年龄的增长，患心力衰竭的风险显著增加。确诊后五年的死亡率在60%到70%之间。与重塑相关的基因表达的变化导致了类似于胎儿基因程序的表达谱；因此，了解心脏的正常发育可能有助于阐明胎儿基因在心脏病理发展中的作用。蛋白激酶A(PKA)是一种依赖cAMP的蛋白激酶，可磷酸化多个细胞靶点，包括一些转录因子。A-激酶锚定蛋白(AKAPs)特异性地结合酶的调节II亚单位(RLL)，并将PKA定位于特定的底物，导致细胞内的局部信号域。PKA依赖的磷酸化水平降低与心衰有关。最近在人心脏cDNA噬菌体展示筛选中分离到了多个重叠的核蛋白Duplin/Chromodomain Helicase Binding Protein 8(CHD8)的PKA结合蛋白。Duplin/CHD8抑制Wnt和STATS介导的胚胎小鼠转录，并与转录抑制因子CTCF一起用于染色质分离。Duplin/CHD8被认为是一种发育蛋白，但也在成人组织中表达。我们假设Duplin/CHD8是一种新的AKAP，并且与Duplin/CHD8结合的PKA调节转录因子STATS的抑制。这种假定的Duplin/CHD8功能与心脏重构和心衰的分子过程有关。Lay摘要：心肌损伤后，心脏中的基因表达发生变化，以模拟发育过程中观察到的变化；然而，这种适应性反应不会长期维持受损的器官，这种情况会迅速恶化为心力衰竭(HF)。细胞信号转导蛋白激酶A(PKA)和转录因子STATS都在HF中受损。这项研究将验证核蛋白Duplin/CHD8介导PKA依赖的STATS调节的假设，探索STATS调节在衰竭心脏中可能出错的潜在机制。

DESCRIPTION (provided by applicant): Following injury to the heart, the myocardium undergoes adaptive changes including hypertrophy, changes in contractility, and altered signaling. This process of 'cardiac remodeling' can ultimately lead to heart failure (HF), which is estimated to affect two percent of Americans, risk for which rises significantly with age. Mortality five years post-diagnosis is between sixty and seventy percent. Changes in gene expression associated with remodeling result in an expression profile similar to the fetal gene program; therefore, understanding normal development of the heart may shed light on the role of fetal genes in the development of heart pathology. Protein Kinase A (PKA) is a cAMP-dependent protein kinase that phosphorylates multiple cellular targets, including a number of transcription factors. A-Kinase Anchoring Proteins (AKAPs) characteristically bind the regulatory II subunits (Rll) of the enzyme and localize PKA to specific substrates, resulting in localized signaling domains within the cell. Decreased PKA-dependent phosphorylation is associated with HF. Multiple overlapping clones of the nuclear protein duplin/chromodomain helicase binding protein 8 (Chd8) were recently isolated in phage display screening of human heart cDNA for PKA binding proteins. Duplin/Chd8 inhibits Wnt and STATS-mediated transcription in the embryonic mouse, and is required for chromatin insulation in conjunction with the transcription represser CTCF. Duplin/Chd8 has been characterized as a developmental protein, but is also expressed adult tissue. We hypothesize that duplin/Chd8 is a novel AKAP and that PKA bound to duplin/Chd8 modulates inhibition of the transcription factor STATS. This hypothesized function of duplin/Chd8 has relevance to the molecular processes underlying cardiac remodeling and HF. Lay Summary: Following myocardial injury, gene expression in the heart changes to mimic that observed in development; however, this adaptive response does not long sustain the injured organ, and this condition can quickly deteriorate into heart failure (HF). The cell signaling kinase protein kinase A (PKA) and the transcription factor STATS are both compromised in HF. This study will test the hypothesis that the nuclear protein duplin/Chd8 mediates PKA-dependent regulation of STATS, exploring a potential mechanism by which STATS regulation could go awry in the failing heart.