Contributions of Cardiac Myosin Binding Protein-C to Healthy and Failing Hearts

摘要：心肌肌球蛋白结合蛋白c对健康和衰竭心脏的贡献。我是一名心脏病专家，在德克萨斯A&M健康科学中心（HSC）医学院担任第二年的助理教授。我相信我的使命是进行有助于心力衰竭治疗的研究，并直接参与心力衰竭患者的治疗。虽然我在科学研究方面接受了良好的教育，但7年的临床培训阻碍了我作为一名独立研究者的发展。因此，我的短期过渡目标包括获得新的技能，开发资源，发表重要的发现，并获得NIH R01水平的资助，以继续向独立研究者发展。这个指导研究职业发展奖（K08）提供了实现这些过渡目标的手段。研究。我将重点阐明心肌肌球蛋白结合蛋白- c （MyBPC3）对健康和衰竭心脏的贡献。40岁的美国人患心力衰竭的风险为20%。保留射血分数（HFpEF）的HF没有有效的治疗方法，其患病率已增加到所有HF病例的50%左右。粗丝肌凝蛋白与细丝肌动蛋白过桥连接，将储存的化学能转化为力量，然后分离的循环形成了心脏收缩和舒张的基础。MyBPC3抑制与肌动蛋白的交叉桥相互作用。MyBPC3的磷酸化可能释放其抑制作用，促进跨桥循环。因此，我假设MyBPC3磷酸化调节过桥循环以增强收缩性（产生力的能力）和柔韧性（放松的能力）。我将通过使用转基因小鼠模型阐明MyBPC3的存在和磷酸化对心脏功能的影响。通过在MyBPC3（- /-）背景下分别删除MyBPC3基因和表达磷酸化模拟MyBPC3突变体来控制MyBPC3的存在和磷酸化。初步数据强烈提示MyBPC3缺失导致HF伴射血分数（HFrEF）降低，MyBPC3磷酸化缺失导致HFpEF。我还将确定使用MyBPC3磷酸化来预防和治疗HFpEF的能力。治疗思路集中在MyBPC3磷酸化介导的收缩性和肌萎缩增强的可能性上，这将维持足够的心功能，而不需要在应激时产生肥厚反应。预防将通过挑战性组成型磷酸化MyBPC3小鼠模型进行测试，该模型通常会导致舒张功能障碍。通过病毒基因转移诱导磷酸化MyBPC3模拟物的表达和应激诱导基因表达将决定治疗潜力。职业发展。一个来自全国各地的专家小组已经集合起来提供指导。该团队由Solaro博士（跨桥自行车细丝调节的主要专家）组成

DESCRIPTION (provided by applicant): Abstract for Contributions of cardiac myosin binding protein-C to healthy and failing hearts Candidate. I am a cardiologist starting 2nd year as an assistant professor at Texas A&M Health Science Center (HSC) College of Medicine. I believe that my calling is to conduct research that can contribute to treatment of heart failure and directly participate in treatment of heart failure patients. Although I've received excellent education in scientific research, 7 total years of required dedicated clinical training has paused my development as an independent investigator. Thus, my short term transitional goals consist of acquiring new skills, developing resources, publishing important findings, and obtaining NIH R01 level funding to continue development toward independent investigator. This mentored research career development award (K08) provides the means to achieve these transitional goals. Research. I will focus on elucidating contributions of cardiac myosin binding protein-C (MyBPC3) to healthy and failing hearts. A 40 year old American has 20% life-time risk of developing heart failure (HF). HF with preserved ejection fraction (HFpEF), which there is no effective treatment, has increased prevalence to ~50% of all HF cases. The cycle of thick filament myosin cross-bridge attaching to actin on the thin filament, converting stored chemical energy to force, and then detaching forms the basis for contraction and relaxation of heart. MyBPC3 inhibits cross-bridge interaction with actin. Phosphorylation of MyBPC3 may release its inhibition to promote cross-bridge cycling. Thus, I hypothesize that MyBPC3 phosphorylation regulates cross- bridge cycling to enhance both contractility (ability to generate force) and lusitropy (ability to relax). I will elucidate the effects of presence and phosphorylation of MyBPC3 on heart function through the use genetically modified mouse models. Control of presence and phosphorylation of MyBPC3 is achieved through deletion of MyBPC3 gene and expression of phosphorylation mimetic MyBPC3 mutants on MyBPC3(- /-) background respectively. Preliminary data strongly suggests that MyBPC3 deletion leads to HF with reduced ejection fraction (HFrEF) and MyBPC3 phosphorylation deficiency leads to HFpEF. I will also determine the ability of using MyBPC3 phosphorylation to prevent and treat HFpEF. Therapeutic idea centers on the possibility that MyBPC3 phosphorylation mediated enhancements of contractility and lusitropy will maintain sufficient cardiac function without needing hypertrophic response during stress. Prevention will be tested through challenging constitutively phosphorylated MyBPC3 mouse model with stress that normally causes diastolic dysfunction. Inducing expression of phosphorylated MyBPC3 mimetic through viral gene transfer and induced gene expression during stress will determine treatment potential. Career Development. An expert team from across the country has assembled to provide mentoring. The team consists of Dr. Solaro (leading expert in thin filament regulation of cross-bridge cycling, primary mentor), Dr. Moss (leading expert in MyBPC3 and thick filament regulation of cross-bridge cycling), and Dr. Redfield (leading authority on HFpEF and expert in large animal models). In addition, Dr. Hajjar (leading expert in using viral gene transfer for HF therapy), will assist as a consultant on construction of virus vectors. Texas A&M portion of the team will provide assurance of institutional support and onsite expertise. I will learn new skills of pressure-volume loop measurements to confirm HFpEF, 2-dimensional fluorescence difference gel electrophoresis to identify post-translation modifications on MyBPC3, stress technique to induce diastolic dysfunction in mice, and viral gene transfer in compliment to inducible gene expression to test targeted MyBPC3 phosphorylation as potential treatment. Through the process, I will have developed new resources of viral gene transfer vector and inducible gene expression construct. Furthermore, the mentoring team will also provide guidance on publication of results and preparation of NIH research project grant (R01). Environment. My primary appointment is with basic science department of system biology and translational medicine (SBTM). The SBTM department has produced independent investigators that went on to hold chairmanships at academic institutions. Start-up package has provided equipment purchases and laboratory space. Both SBTM and Texas A&M HSC have investigators at various levels who have the skills and are enthusiastic to collaborate. Texas A&M HSC has guaranteed protected 75% effort dedicated to this research for 5-years independent of receiving K08 award funding. Furthermore, Texas A&M HSC has agreed to return all salary savings generated from K08 award; therefore, this agreement provides a multiplication effect on the K08 award. Thus, I reside in an excellent environment to develop as an independent investigator. Summary. Accomplishing these proposed studies will provide new skills, resources, and discoveries. Thus, funding this proposal will help to solve a vexing health problem and enable a beginning clinician scientist toward path of independent research. PUBLIC HEALTH RELEVANCE: A 40-year old American has 1 in 5 chance of developing heart failure during rest of his/her life. Heart failure kills 50% of its victims in 5 years. Cardic myosin binding protein-C (MyBPC3) is a component of the heart muscle. MyBPC3 regulates the speed of motor-like proteins that cause the heart to contract and relax with each beat. This project seeks to understand how MyBPC3 malfunction can cause heart failure. Furthermore, this project will determine the ability of using modified form of MyBPC3 to prevent and treat heart failure.