Mechanisms of Gene Silencing of Friedreich's Ataxia

Friedreich共济失调的基因沉默机制

• 批准号: 9128068
• 负责人: JOEL M. GOTTESFELD
• 金额: $ 42.11万
• 依托单位: SCRIPPS RESEARCH INSTITUTE, THE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-15 至 2019-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9128068
• 关键词: Acute; Affect; Afferent Neurons; Biochemistry; Biological Assay; Biological Markers; Blood - brain barrier anatomy; Brain; Canis familiaris; Cardiac; Cardiac Myocytes; Cardiomyopathies; Cause of Death; Cell Line; Cell model; Cells; Chronic; Clinical; Clinical Trials; Data; Development; Disease; Disease model; Epigenetic Process; Exhibits; FDA approved; Friedreich Ataxia; Functional disorder; Gene Activation; Gene Expression; Gene Expression Profile; Gene Silencing; Genes; Genetic Transcription; Health; Heart; Histone Deacetylase Inhibitor; Human; Inherited; Introns; Length; Lymphocyte; Mediating; Messenger RNA; Methods; Mitochondria; Mitochondrial Proteins; Modeling; Molecular; Mus; Neurodegenerative Disorders; Neurons; Pathology; Patients; Peripheral; Pharmaceutical Chemistry; Pharmaceutical Preparations; Pharmacodynamics; Phase; Preclinical Drug Evaluation; Proteins; Research Personnel; Secondary Myocardial Diseases; Spinal Ganglia; Spinocerebellar Ataxias; Testing; Therapeutic; Time; Toxic effect; Trinucleotide Repeats; adenoviral-mediated; base; cell type; design; effective therapy; efficacy trial; frataxin; homologous recombination; human subject; improved; induced pluripotent stem cell; member; mitochondrial dysfunction; mouse model; neuropathology; novel; novel therapeutics; patient population; research study; treatment duration

DESCRIPTION (provided by investigator): This application is aimed at understanding the molecular basis for the neurodegenerative disease Friedreich's ataxia (FRDA) and development of novel therapeutics. FRDA is one of the triplet-repeat diseases, where expansion of GAA.TTC repeats within the FXN gene, encoding the essential mitochondrial protein frataxin, leads to epigenetic transcriptional silencing. Loss of frataxin results in a spinocerebellar ataxia with secondary cardiomyopathy, which is the major cause of death in FRDA patients. At present there is no approved therapy for FRDA. Since the GAA.TTC repeats are in an intron, and do not affect the sequence of frataxin protein, gene activation would be of therapeutic value. We identified members of the 2-aminobenzamide class of HDAC inhibitors as potent activators of FXN transcription. These molecules cross the blood brain barrier in mice and canines, exhibit no acute or chronic toxicity, and increase FXN mRNA and frataxin protein levels in the brain and heart in the mouse FRDA model, as well as in circulating lymphocytes in drug-treated FRDA patients in a Phase Ib human clinical trial. While these data provide a proof of concept for this therapeutic approach, our current compounds suffer from pharmacological limitations that preclude their use in chronic treatment. Through a medicinal chemistry effort, we have identified new compounds that have solved these limitations, and one such molecule is being taken forward as a new clinical candidate. During the previous application period, we generated induced pluripotent stem cells (iPSCs) from FRDA patients and differentiated these cells along the neuronal lineage. We have used these cells to model FRDA to study FXN gene silencing and for drug screening. In the present application, we plan to (1) optimize methods for the differentiation of hiPSCs to sensory neurons, the major cell type affected in FRDA, and to use these cells to model the disease through global gene expression studies and markers of mitochondrial dysfunction. For these experiments, we will use helper-dependent adenovirus-mediated homologous recombination to generate isogenic cell lines have the GAA¿TTC repeats "corrected" to normal lengths. (2) Since cardiomyopathy is the major cause of death in FRDA, we will also model the disease in FRDA iPSC-derived cardiomyocytes. (3) We will use these two FRDA cell models to ask if improved HDAC inhibitors can reverse FRDA gene expression signatures and FRDA mitochondrial pathology. (4) Lastly, we will use neuronal cells and patient lymphocytes to identify gene expression biomarkers to be used in Phase II efficacy studies in FRDA patients. Our studies are at the forefront of development of a novel therapeutic for this currently untreatable and lethal disease.

描述（由研究人员提供）：此应用旨在了解弗里德里希共济失调（FRDA）的神经退行性疾病的分子基础和新型治疗的发展。 FRDA是三胞胎重复疾病之一，其中gaa.ttc在FXN基因内重复的扩展，编码必需的线粒体蛋白frataxin，导致表观遗传转录沉默。 frataxin的丧失导致患有继发性心肌病的脊髓性共济失调，这是FRDA患者的主要死亡原因。目前，FRDA尚无批准的疗法。由于GAA.TTC重复序列在内含子中，并且不影响Frataxin蛋白的序列，因此基因激活将具有热值。我们将HDAC抑制剂的2-氨基苯甲酰胺类别的成员确定为FXN转录的潜在活化剂。这些分子在小鼠和犬类中穿过血脑屏障，在小鼠FRDA模型中的大脑和心脏中的FXN mRNA和FRATAXIN蛋白水平增加，并增加了FXN mRNA和FRATAXIN蛋白水平，以及在同期IB人类临床试验中，在药物治疗的FRDA患者中循环的淋巴细胞。尽管这些数据为这种治疗方法提供了概念证明，但我们当前的化合物遭受了药物限制，这些局限性排除了它们在慢性治疗中的使用。通过药物化学工作，我们确定了解决这些局限性的新化合物，并且将这样一个分子作为新的临床候选者前进。在上一个申请期间，我们从FRDA患者产生了诱导的多能干细胞（IPSC），并沿着神经元谱系区分了这些细胞。我们已经使用这些细胞对FRDA进行建模，以研究FXN基因沉默和药物筛查。在本应用中，我们计划（1）优化HIPSC与感觉神经元的分化的方法，即在FRDA中受影响的主要细胞类型，并使用这些细胞通过全球基因表达研究和线粒体功能障碍的标志物来对疾病进行建模。对于这些实验，我们将使用辅助性腺病毒介导的同源重组来产生等源性细胞系具有GAA€ttc重复序列“校正”到正常长度。 （2）由于心肌病是FRDA死亡的主要原因，因此我们还将在FRDA IPSC衍生的心肌细胞中对该疾病进行建模。 （3）我们将使用这两个FRDA细胞模型询问改进的HDAC抑制剂是否可以逆转FRDA基因表达特征和FRDA线粒体病理学。 （4）最后，我们将使用神经元细胞和患者淋巴细胞来鉴定在FRDA患者的II期有效研究中使用的基因表达生物标志物。我们的研究处于开发这种新疗法的最前沿，用于这种目前不可治疗和致命的疾病。