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.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 心肌肌球蛋白结合蛋白C（cMyBP-C）磷酸化在心力衰竭中发生变化，可能是心功能的重要调节因子。我们最近发现，基因消融和蛋白激酶A介导的（PKA）磷酸化cMyBP-C似乎导致肌球蛋白横桥的径向或方位角位移，使横桥位于更远离肌球蛋白的粗丝表面和更接近肌动蛋白的细丝。肌原纤维蛋白（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（PO 4）分子，这诱导蛋白质结构的构象变化。虽然我们已经发现cMyBP-C的PKA磷酸化调节肌动蛋白的交叉桥的处置和可用性，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未解决。为了测试这一点，我们评估了赤道反射（I11/I10）的强度，使用低角X射线衍射，以确定在心肌中的四行突变小鼠的横桥的位置。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、组成性磷酸化的cMyBP-C突变蛋白、正常cMyBP-C蛋白和与不可磷酸化的心肌肌钙蛋白I（cTnI）一起表达的正常cMyBP-C，因为cTnI磷酸化也影响收缩。我们假设，与PKA位点磷酸化cMyBP-C的负电荷将足以解除物理约束的交叉桥，可能是通过破坏cMyBP-C结合肌球蛋白的S2区。