Expanding the Pathogenic Mechanisms of Calmodulinopathies

扩展钙调蛋白病的致病机制

• 批准号: 10426462
• 负责人: Ivy E Dick
• 金额: $ 23.18万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-03-01 至 2024-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10426462
• 关键词: Action Potentials; Arrhythmia; Binding; Biological Models; Biophysics; Brain; Calcium; Calcium Channel; Calmodulin; Cardiac; Cell physiology; Cells; Closure by clamp; Coupling; DNA Sequence Alteration; Development; Disease; Electrophysiology (science); Elements; Exhibits; Family; Feedback; Fluorescence Resonance Energy Transfer; Future; Genetic Transcription; Heart; Human; Hybrids; Image; Immune system; Impairment; Incidence; Induced pluripotent stem cell derived neurons; Life; Lobe; Mediating; Morphology; Muscle Contraction; Mutation; Neurologic; Neurologic Deficit; Neurologic Dysfunctions; Neurons; Neuropathogenesis; Pathogenesis; Pathogenicity; Pathology; Patients; Phenotype; Play; Process; Proteins; Regulation; Research; Role; Signal Transduction; Source; Symptoms; Tail; Toxin; biophysical analysis; comorbidity; electrical property; gain of function; heart function; heart rhythm; induced pluripotent stem cell; interest; loss of function; mutant; neuronal excitability; neuropathology; neuropsychiatry; neurotransmission; patch clamp; sensor; stem cell model; voltage; voltage clamp

Calmodulin (CaM) is a ubiquitous calcium sensor, vital to immune system, heart and brain function. Mutations within CaM result in a set of disorders known as calmodulinopathies. Patients harboring these CaM mutations suffer from life-threatening cardiac arrhythmias, which are often accompanied by neurodevelopmental delay or other neurological dysfunction. While CaM has numerous potential targets which may be altered in calmodulinopathies, voltage gated calcium channels (VGCCs) stand out as likely pathogenic elements. For CaV1-2 channels, CaM is known to preassociate with the carboxy-tail of the channel. Upon binding Ca2+, this resident CaM initiates either of two important forms of feedback regulation; Ca2+/CaM dependent inactivation (CDI) or Ca2+/CaM dependent facilitation (CDF). Each of these forms of channel regulation can be independently driven by a single lobe of CaM, with CaV1.2, CaV1.3 and CaV2.1 each strongly modulated by Ca2+ binding to the C-lobe of CaM. As the majority of calmodulinopathy mutations have thus-far impacted the CaM C-lobe, this lobe-specific regulation implies a large impact of calmodulinopathy mutations on the regulation of these three channels. In fact, we have previously demonstrated that calmodulinopathy mutations are capable of disrupting the CDI of CaV1.2 channels, resulting in the long-QT phenotype seen in patients6,7. However, the effect of CaM mutations on VGCCs other than CaV1.2 has yet to be elucidated, nor have the mechanisms underlying the neurological phenotypes of calmodulinopathy patients been explored. As CaV1-2 channels play critical roles in neuronal excitability, excitation-transcription coupling, and neurotransmission, we propose that they are likely contributors to the neuropathogenesis of calmodulinopathies. We will therefore undertake a biophysical study of the impact of calmodulinopathy mutations across the CaV1-2 channel family and evaluate the impact of these mutations on neuronal function. In particular, we hypothesize that CaM mutations which alter the Ca2+ binding to the C-lobe of the protein will decrease CDI in CaV1.2 and CaV1.3, and disrupt CDF in CaV2.1. To evaluate the functional impact of these mutations, we will generate induced pluripotent stem cell derived neurons (iPSC-neurons) from calmodulinopathy patients, and elucidate a cellular phenotype correlating with the neurological deficits of calmodulinopathy patients. Thus, we will undertake one of the first studies aimed at understanding the impact of calmodulinopathy mutations outside the heart, expanding our understanding of the pathogenic mechanisms underlying this disorder.

钙调蛋白（CAM）是一种无处不在的钙传感器，对免疫系统，心脏和大脑功能至关重要。突变 在CAM中导致一组被称为钙调整病的疾病。携带这些CAM突变的患者 患有威胁生命的心律不齐，通常伴随着神经发育延迟或 其他神经功能障碍。凸轮具有许多潜在目标，可能会改变 钙调蛋白病，电压门控钙通道（VGCC）脱颖而出。为了 CAV1-2频道，CAM已知与该通道的羧基尾巴进行预先关联。绑定Ca2+，这是 居民CAM启动了两种重要形式的反馈法规中的任何一种； Ca2+/CAM依赖性失活 （CDI）或CA2+/CAM依赖性促进（CDF）。这些形式的渠道调节中的每一个都可以独立 由CAM的单个叶驱动，cav1.2，cav1.3和cav2.1由Ca2+结合强烈调节 C-Lobe of Cam。由于大多数钙调整疾病突变已经影响了凸轮c-lobe，所以 叶特异性调节意味着钙调司抑制突变对这三个调节的重大影响 频道。实际上，我们以前已经证明了钙调整疾病突变能够破坏 Cav1.2通道的CDI，导致患者6,7的长QT表型。但是，凸轮的效果 除CAV1.2以外的VGCC上的突变尚未阐明，也没有基础的机制 探索了钙调整病患者的神经表型。随着CAV1-2频道在 神经元兴奋性，激发转录耦合和神经传递，我们建议它们可能是 导致钙调蛋白病的神经病作用的原因。因此，我们将对 CAV1-2渠道家族中钙调整性疾病突变的影响并评估这些影响的影响 神经元功能的突变。特别是，我们假设会改变Ca2+结合的CAM突变 蛋白质的C-Lobe将减少Cav1.2和Cav1.3中的CDI，并在Cav2.1中破坏CDF。评估 这些突变的功能影响，我们将从钙调胰岛细胞病患者中产生诱导的多能干细胞衍生的神经元（IPSC-神经元），并阐明与神经系统相关的细胞表型 钙调整病患者的缺陷。因此，我们将进行旨在理解的第一项研究之一 心脏外的钙调胰岛细胞病突变的影响，扩大我们对病原体的理解 这种疾病的基础机制。