ROLE OF CMYBP-C IN THE REGULATION OF MYOCARDIUM

CMYBP-C 在心肌调节中的作用

• 批准号: 7954897
• 负责人: Richard L Moss
• 金额: $ 3.26万
• 依托单位: ILLINOIS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7954897
• 关键词: Ablation; Actins; Affect; Binding; Biophysics; Cardiac; Cardiac Myosins; Charge; Computer Retrieval of Information on Scientific Projects Database; Cyclic AMP-Dependent Protein Kinases; Funding; Genetic; Grant; Heart failure; Institution; Mediating; Mutant Strains Mice; Mutation; Myocardium; Myosin ATPase; Phosphorylation; Positioning Attribute; Proteins; Radial; Regulation; Research; Research Personnel; Resources; Role; Serine; Site; Source; Surface; Testing; Thick Filament; Thin Filament; Threonine; Troponin I; United States National Institutes of Health; X ray diffraction analysis; X-Ray Diffraction; citrate carrier; inorganic phosphate; mutant; myosin-binding protein C; protein structure

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Cardiac myosin binding protein-C (cMyBP-C) phosphorylation changes in heart failure and may be a significant modulator of cardiac function. We have recently shown that both genetic ablation and protein kinase A-mediated (PKA) phosphorylation of cMyBP-C appear to result in radial or azimuthal displacement of myosin cross-bridges, such that cross-bridges are located further from the surface of the thick filament of myosin and closer to the thin filament of actin. Reversible PKA phosphorylation of myofibrillar proteins, such as cMyBP-C, involves the addition of a negatively charged phosphate (PO4) molecule on a serine or threonine residue, which induces a conformational change in the structure of the protein. While we have found PKA phosphorylation of cMyBP-C to modulate the disposition and availability of cross-bridges to actin, it remains unresolved whether or not this mechanism of cMyBP-C function is attributed to the negative charge associated with phosphorylation. To test this, we assessed the intensities of equatorial reflections (I11/I10) using low-angle X-ray diffraction to determine the position of cross-bridges in myocardium from four lines of mutant mice. The mutations include four pertinent states of myofibrillar phosphorylation: non-phosphorylatable cMyBP-C mutant protein, constitutively-phosphorylated cMyBP-C mutant protein, normal cMyBP-C protein, and normal cMyBP-C expressed with non-phosphorylatable cardiac troponin I (cTnI) since cTnI phosphorylation also affects contraction. We hypothesize that the negative charge associated with phosphorylation of PKA sites in cMyBP-C will be sufficient to relieve a physical constraint on cross-bridges, possibly by disrupting cMyBP-C binding to the S2-region of myosin.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目和 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 心脏肌球蛋白结合蛋白-C (cMyBP-C) 磷酸化在心力衰竭中发生变化，可能是心脏功能的重要调节剂。我们最近表明，cMyBP-C 的基因消融和蛋白激酶 A 介导的 (PKA) 磷酸化似乎都会导致肌球蛋白跨桥的径向或方位位移，使得跨桥距离厚膜表面更远。肌球蛋白的细丝，更接近肌动蛋白的细丝。肌原纤维蛋白（例如 cMyBP-C）的可逆 PKA 磷酸化涉及在丝氨酸或苏氨酸残基上添加带负电荷的磷酸盐 (PO4) 分子，从而诱导蛋白质结构的构象变化。虽然我们发现 cMyBP-C 的 PKA 磷酸化可以调节肌动蛋白跨桥的配置和可用性，但 cMyBP-C 功能的这种机制是否归因于与磷酸化相关的负电荷仍然悬而未决。为了测试这一点，我们使用低角度 X 射线衍射评估了赤道反射 (I11/I10) 的强度，以确定四系突变小鼠心肌中横桥的位置。这些突变包括肌原纤维磷酸化的四种相关状态：不可磷酸化的 cMyBP-C 突变蛋白、组成型磷酸化的 cMyBP-C 突变蛋白、正常的 cMyBP-C 蛋白以及用不可磷酸化的心肌肌钙蛋白 I (cTnI) 表达的正常 cMyBP-C因为 cTnI 磷酸化也会影响收缩。我们假设与 cMyBP-C 中 PKA 位点磷酸化相关的负电荷足以缓解跨桥的物理限制，可能是通过破坏 cMyBP-C 与肌球蛋白 S2 区的结合来实现的。