Understanding the mechanisms that modulate the effects of mutant Huntingtin lowering in aging Huntington's disease model mice

了解调节衰老亨廷顿病模型小鼠突变亨廷顿蛋白降低效应的机制

• 批准号: 10556339
• 负责人: Scott Zeitlin
• 金额: $ 41.5万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-01 至 2027-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10556339
• 关键词: 20q; Actins; Affect; Age; Age Months; Aging; Alleles; Antisense Oligonucleotides; Astrocytosis; Attenuated; Behavioral; Brain; Brain region; Cell Nucleus; Cell physiology; Cognitive; Corpus striatum structure; DNA Damage; DNA Repair; Deep Cervical Lymph Node; Disease; Disease Progression; Disease model; Elements; Encephalitis; Future; Gene Expression; Genes; Gliosis; Huntington Disease; Huntington gene; Impairment; Inflammasome; Introns; Isopropyl Thiogalactoside; Kinetics; Knock-in; Lac Repressors; Ligation; Long-Term Effects; Lymphatic function; Measures; Meningeal lymphatic system; MicroRNAs; Modeling; Monitor; Motor; Mus; Mutation; Neurodegenerative Disorders; Nuclear Inclusion; Onset of illness; Outcome; Pathogenesis; Pathway interactions; Phase III Clinical Trials; Phenotype; Physiological; Proteins; Quantitative Reverse Transcriptase PCR; RNA; RNA Splicing; Reporter; Safety; Single-Stranded DNA; Site; Stains; Stretching; Symptoms; System; Testing; Therapeutic; Therapeutic Intervention; Therapeutic Uses; Time; Transcript; Transcription Initiation Site; Transgenes; Trinucleotide Repeats; Withdrawal; age related; aged; aging brain; autosome; behavioral phenotyping; cohort; cytokine; efficacy testing; gain of function; genetic signature; insight; knock-down; lymphatic drainage; motor symptom; mouse model; mutant; neuroinflammation; neuropathology; oxidative DNA damage; polyglutamine; preclinical study; promoter; repaired; response; therapeutic development; therapeutic target; transcriptome

Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder that is caused by the expansion of a CAG triplet repeat encoding a stretch of polyglutamine (polyQ) within Huntingtin (HTT), the protein product of the HD gene. The HD mutation confers a deleterious gain-of-function, possibly via the expression of both toxic RNA transcripts and protein, together with potential loss of normal HTT function that affects a variety of cellular functions. A number of HTT lowering strategies are being developed–Phase III clinical trials testing the efficacy of anti-sense oligonucleotides (ASOs) targeting either total HTT expression or selectively mutant HTT (mHTT) expression are underway, while Htt lowering using other approaches (miRNA and splicing modulators) are currently in safety/tolerability trials or will begin such trials shortly. Many of the initial preclinical studies, however, did not examine the long-term effects of Htt lowering in aged models. Using a regulatable HD mouse model whose mHtt expression or total Htt expression are controlled via a Lac operator/repressor system, we found that global pre-symptomatic ~50% Htt lowering (starting prior to 3 months of age) of either mutant or total Htt expression was more beneficial in ameliorating HD mouse model phenotypes in comparison to later lowering (starting at 6 months of age or later), and that there were no obvious detrimental consequences from lowering total Htt expression in comparison to the allele-specific lowering of mHtt expression. However, we observed that in older mice, the beneficial effects of earlier Htt lowering were attenuated for some, but not all HD model phenotypes. We hypothesize that: (1) brain regions respond differentially to the amount and/or timing of mHtt lowering, and aging may exacerbate this effect, and (2) >50% reduction of mHtt expression may be needed to maintain homeostatic cellular and physiological functions whose efficiency declines with age. To test these hypotheses, and to provide a better understanding of how lowering mHtt expression affects homeostatic functions in older mice, we propose three aims. In (Aim 1), we will characterize the effects of globally lowering mHtt expression by ~75% using a different strain of Lac- regulatable HD mouse model to determine if the benefits of mHtt lowering can be extended beyond 12 months of age for all HD mouse model phenotypes. To determine if the DNA damage response and neuroimmflamation, two critical homeostatic functions that decline with age, can modulate the effect of mHtt lowering in older mice, we propose to characterize the DNA damage response in (Aim 2), while in (Aim 3), we propose to characterize activation of the inflammasome and measure meningeal lymphatic function in our mHtt-lowered mice and controls. Together, these aims should provide new insight into the degree of mHtt lowering that is needed to impact HD pathogenesis in aging mice. In addition, determining if two age-related pathways correlate with mHtt expression levels and/or HD model phenotypes could provide new potential therapeutic targets to be explored for the treatment of HD.

亨廷顿氏病（HD）是一种常染色体显性神经退行性疾病，是由 在Huntingtin（HTT）中编码一系列聚谷氨酰胺（Polyq）的CAG三重态扩展， 高清基因的蛋白质产物。高清突变承认有害的功能，通过 毒性RNA转录本和蛋白质的表达，以及正常HTT功能的潜在丧失 影响多种细胞功能。许多HTT降低策略正在开发 - 阶段III 临床试验测试针对总HTT表达或的抗义寡核苷酸（ASO）的效率 有选择性突变htt（MHTT）表达正在进行中，而HTT使用其他方法降低（miRNA） 和剪接调节器）目前正在进行安全/出租性试验中，或者很快就会开始此类试验。许多 然而，最初的临床前研究未检查老年模型中HTT降低的长期影响。使用 可调节的HD小鼠模型，其MHTT表达或总HTT表达通过LAC控制 操作员/阻遏系统，我们发现全球症状前〜50％降低了HTT（从3个月之前开始） 突变体或总HTT表达的年龄）对改善HD小鼠模型更有益 与后来的降低相比（从6个月或更晚起）的表型，没有 与等位基因特异性相比，降低总HTT表达的明显有害后果 降低MHTT表达。但是，我们观察到，在较老的小鼠中，早期HTT的有益作用 降低的某些HD模型表型减弱了。我们假设：（1）大脑区域 对MHTT降低的数量和/或时间的反应不同，并且衰老可能会加剧这种影响，并且 （2）>维持稳态细胞和生理的MHTT表达可能需要降低50％ 效率随着年龄的增长而下降的功能。检验这些假设，并提供更好的理解 关于降低MHTT表达如何影响老鼠老鼠的稳态功能，我们提出了三个目标。在（目标 1），我们将使用不同的lac- 可调节的HD鼠标模型以确定MHTT降低的益处是否可以扩展到12个月以上 所有HD小鼠模型表型的年龄。确定DNA损伤响应和 神经摄像机，两个关键的稳态功能随着年龄的增长而下降，可以调节MHTT的效果 降低老鼠的降低，我们建议在（AIM 2）中表征DNA损伤响应，而在（AIM 3）中，我们 提出表征激活炎性体和测量脑膜淋巴功能的提议 MHTT较低的小鼠和对照。这些目标共同为MHTT程度提供新的见解 降低衰老小鼠的HD发病机理所需的降低。另外，确定是否与年龄有关 途径与MHTT表达水平和/或HD模型表型相关，可以提供新的潜力 用于治疗HD的治疗靶标。