Molecular Pathways of Heart K Channel Regulation

EXCEED提供的空间。长期目标是揭示妊娠期间功能性肥厚和产后恢复过程中涉及心脏电和分子重塑的细胞和分子机制，特别是与K*通道表达/功能相关的机制。/TOK决定了啮齿动物和人类的心脏动作电位持续时间。在衰竭的肥厚心脏中，分子成分，特别是Kv4.3和Kv4.2通道下调，动作电位时程延长，心律失常发生。在怀孕期间，心律失常的风险增加，心脏出现功能性肥大，激素水平急剧变化；然而，目前还没有关于性激素诱导的K表达/功能变化的研究，可以解释怀孕期间的心脏风险，以及它们在分娩后的可逆性。因此，主要的假设是，在怀孕和产后，性激素可能以基因组或非基因组的方式调节Ito电流成分(如Kv1.4、Kv4.2、Kv4.3、KChlP2、MiRP1、频率蛋白)。初步研究表明：a)妊娠时心脏Kv4.3、Kv1.4和Kch/P2，而不是Kv4.2通道/转录本减少，Kv4.3蛋白表达减少；b)与妊娠时一样，17-[3-雌二醇/(E_2)]处理使心脏Kv4.3和Kv1.4m RNA减少；c)E_2降低培养的Adu/t心肌细胞Kv4.3蛋白的表达；d)E_2对电流有双重作用，在100 nM处(与人妊娠相似)，它缩短动作电位，增加幅度；而10 PM E_2则产生相反的作用；e)c-Src酪氨酸激酶被E_2激活，从肥大开始，Kv4.3的表达减少；f)酪氨酸激酶的激活产生动作电位和/或电流降低。我们将主要使用小鼠和多种实验方法。其具体目的是：1)研究孕期和产后早期动作电位的重构、快电流(/to-f)和慢电流(/to-s)以及潜在的分子成分。2)研究E_2对Ito.fllto.s电流及其分子组成的作用，以及E_2是否通过c-Src/MAPK(ERK)轴刺激Kv4.3基因转录。3)研究和确定了E_2对Ito.fand Kv4.3通道的非基因组调控机制(S)。4)研究c-Src依赖的酪氨酸磷酸化对电流和Kv4亚型的短期和长期作用。5)确定Kv4.3中参与c-Src调控的基序。这些研究将为肥厚早期导致心肌K*通道重构的细胞和分子机制提供新的信息，并有助于设计预防医学的新策略。表演网站========================================Section End===========================================

EXCEEDTHE SPACE PROVIDED. The long term goal is to unravel cellular and molecular mechanisms involved in cardiac -electrical and molecular- remodeling during functional hypertrophy in pregnancy, and recovery in postpartum; in particular, those related to K* channel expression/function. /toK shapes the cardiac action potential duration in both rodents and humans. In failing hypertrophic hearts, /to-fmolecular components, in particular Kv4.3 and Kv4.2 channels are downregulated increasing action potential duration and arrhythmogenesis. During pregnancy, there is an increased risk of arrhythmias, the heart develops functional hypertrophy, and hormone levels dramatically change; however, no studies are available on chanqes in K expression/function induced by sex hormones, that may explain the cardiac risks durin.qpre,qnancyor their reversibility after delivery. Thus, the main hypothesis is that, during pregnancy and postpartum, sex hormones may regulate Ito current components (e.g. Kvl.4, Kv4.2, Kv4.3, KChlP2, MiRP1, frequenin) in a genomic or non-genomic fashion. Preliminary Studies show that: a) cardiac Kv4.3, Kvl.4 and KCh/P2, but not Kv4.2 channe/ transcripts, and Kv4.3 protein were reduced in/ate pregnancy; b) as in pregnancy, 17-[3-estradio/(E2) treatment reduced cardiac Kv4.3 and Kvl.4 mRNA; c) E2 reduced Kv4.3 protein expression in cu/tured adu/t myocytes; d) E2 had dua/ effects on/to currents, at 100 nM (similar to/ate human pregnancy), it shortened the action potentia/ and increased/to amp/itude; whereas, an opposite effect was produced by 10 pM E2; e) c-Src tyrosine kinase, which is activated by E2 and from the onset of hypertrophy, reduced expression of Kv4.3; and f) tyrosine kinase activation produced action potentia/ pro/ongation and/to current reduction. We will mainly use mice and multiple experimental approaches. The Specific Aims are to: 1) Investigate, during pregnancy and early post- partum, the remodeling of action potentials, and of/to fast (/to-f)and/to slow (/to.s)currents, and underlying molecular components. 2) Investigate the action of E2 on Ito.fllto.scurrents and their molecular components, and if E2 stimulates Kv4.3 gene transcription through the c-Src/MAPK(ERK) axis. 3) Characterize and define the mechanism(s) of non-genomic regulation of Ito.fand Kv4.3 channels by E2. 4) Investigate short- and long-term actions of c-Src-dependent tyrosine phosphorylation on/to currents and Kv4 isoforms. 5) Determine the motifs in Kv4.3 involved in its regulation by c-Src. These studies should provide new informationon the cellular and molecular mechanisms leading to the remodeling of cardiac K* channels inthe early stagesof hypertrophy,and help in the designof new strategiesfor preventiveMedicine. PERFORMANCE SITE ========================================Section End===========================================