Expanding the Pathogenic Mechanisms of Calmodulinopathies

扩展钙调蛋白病的致病机制

基本信息

批准号：
10580095
负责人：
Ivy E Dick
金额：
$ 19.31万
依托单位：
UNIVERSITY OF MARYLAND BALTIMORE
依托单位国家：
美国
项目类别：
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/10580095
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 Developmental Delay Disorders 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 P-Q type voltage-dependent calcium channel Pathogenesis Pathogenicity Pathology Patients Phenotype Play Process Proteins Regulation Research Role Signal Transduction Source Symptoms Tail Toxin biophysical analysis comorbidity electrical property experimental study 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

项目摘要

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) 是一种普遍存在的钙传感器，对免疫系统、心脏和大脑功能至关重要。突变 CaM 内的异常会导致一系列称为钙调蛋白病的疾病。携带这些 CaM 突变的患者患有危及生命的心律失常，通常伴有神经发育迟缓或其他神经功能障碍。虽然 CaM 有许多潜在目标，但这些目标可能会在在钙调蛋白病中，电压门控钙通道（VGCC）是可能的致病因素。为了 CaV1-2 通道，已知 CaM 与通道的羧基尾预关联。结合 Ca2+ 后，这驻地 CaM 启动两种重要的反馈调节形式之一； Ca2+/CaM 依赖性失活 (CDI) 或 Ca2+/CaM 依赖性促进 (CDF)。这些渠道监管形式中的每一种都可以独立地进行由 CaM 单叶驱动，CaV1.2、CaV1.3 和 CaV2.1 均受到与 Ca2+ 结合的强烈调节 CaM 的 C 叶。由于迄今为止大多数钙调蛋白病突变都影响了 CaM C 叶，因此叶特异性调节意味着钙调蛋白病突变对这三个区域的调节有很大影响渠道。事实上，我们之前已经证明钙调蛋白病突变能够破坏 CaV1.2 通道的 CDI，导致患者出现长 QT 表型6,7。然而，CaM 的作用除 CaV1.2 之外的 VGCC 突变尚未阐明，也未阐明其背后的机制钙调蛋白病患者的神经表型已被探索。 CaV1-2 通道在神经元兴奋性、兴奋转录耦合和神经传递，我们认为它们很可能钙调蛋白病的神经发病机制的贡献者。因此，我们将进行生物物理学研究钙调蛋白病突变对 CaV1-2 通道家族的影响并评估这些影响神经元功能的突变。特别是，我们假设 CaM 突变会改变 Ca2+ 结合到蛋白质的 C 叶将降低 CaV1.2 和 CaV1.3 中的 CDI，并破坏 CaV2.1 中的 CDF。评估为了了解这些突变的功能影响，我们将从钙调蛋白病患者中产生诱导性多能干细胞衍生神经元（iPSC-神经元），并阐明与神经系统相关的细胞表型钙调蛋白病患者的缺陷。因此，我们将进行首批研究之一，旨在了解心脏外钙调蛋白病突变的影响，扩大了我们对致病原因的了解这种疾病的潜在机制。