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Novel knock-in mouse models of spinocerebellar ataxia type 12

脊髓小脑共济失调 12 型新型敲入小鼠模型

基本信息

批准号：
9975258
负责人：
Pan Li
金额：
$ 45.03万
依托单位：
JOHNS HOPKINS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-04-01 至 2023-09-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9975258
关键词：
5&apos Flanking Region Abnormal coordination Age Alleles Alternative Splicing Amino Acids Animal Experiments Antibodies Ataxia Atrophic Behavior Brain CAG repeat Cell model Cells Cerebellum Cerebral cortex Cerebrum Clustered Regularly Interspaced Short Palindromic Repeats Data Development Disease Exons Funding Gait abnormality Genes Holoenzymes Human Huntington Disease Hyperactive behavior Initiator Codon Knock-in Knock-in Mouse Length Longevity Magnetic Resonance Imaging Modeling Molecular Motor Mus Mutation N-terminal Nerve Degeneration Neurodegenerative Disorders Neurologic Onset of illness Open Reading Frames Pathogenesis Pathogenicity Pattern Phenotype Phosphorylation Process Property Protein Isoforms Protein phosphatase Proteins Purkinje Cells RNA Splicing Reading Frames Research Reverse Transcriptase Polymerase Chain Reaction Serine Spinocerebellar Ataxias Syndrome System Testing Therapeutic Tissues Toxic effect Transcript Translations Tremor Triplet Multiple Birth United States National Institutes of Health Validation Variant behavior test cerebral atrophy experimental study falls genetic pedigree genomic locus homologous recombination in vitro Model induced pluripotent stem cell innovation insight mouse model neuroimaging neuropathology neuropsychiatry neurotoxicity novel promoter therapeutic target transcriptome

项目摘要

PROJECT SUMMARY Spinocerebellar ataxia type 12 (SCA12) is a rare neurodegenerative disease caused by a CAG/CTG expansion in exon 7 of PPP2R2B, a gene encoding regulatory units of the protein phosphatase 2A. SCA12 is characterized by tremor, gait abnormalities, and psychiatric syndromes. Neuropathologically, the single SCA12 brain that has become available revealed prominent atrophy of the cerebral cortex and cerebellum, with a noted loss of Purkinje cells consistent with MRI findings in multiple pedigrees. PPP2R2B transcript is alternatively spliced with at least eight variants, each with a different N-terminal region. The repeat in exon 7 is itself included in at least three splice variants. In two variants, the repeat falls into ORFs predicted to encode the poly serine (polySer) tracts, giving rise to short polySer tracts from the normal allele and long polySer tracts from the expanded allele. Our preliminary data from cell systems suggests that even in the absence of AUG start codons, long polySer may be produced by repeat associated non-AUG (RAN) translation, and that proteins with a long polySer, but not a short polySer, have toxic properties. By CRISPR-assisted homologous recombination, we have successfully generated a humanized SCA12 knock-in (KI-10 or 80) mouse model, in which the mouse exon 2 was replaced by its human counterpart exon 7 with 10 or 80 CAG triplets. We hypothesize that the SCA12 KI-80 mouse model will recapitulate some features of the human SCA12 disease; and that poly amino acid tracts, especially long polySer, may be expressed in SCA12 KI-80, triggering toxicity hence SCA12 pathogenesis, and that the repeat expansion may alter PPP2R2B splicing and expression. In Aim 1, we will perform behavioral testing, neuropathology studies and neuroimaging to characterize the novel SCA12 KI-80 mouse model, along with its control SCA12 KI-10 model and WT. In Aim 2, we will determine the expression and potential toxicity of the predicted polySer containing proteins in SCA12 KI mice by correlating the polySer expression and aggregation with the progression of the mouse phenotype, behavior abnormalities and brain atrophy. We will examine the splicing and expression of PPP2R2B by RT-PCR and qPCR in KI-80, compared with KI-10 and WT. The proposed experiments provide some of the first steps in determining potential therapeutic targets for SCA12, and the appropriate models for testing rational therapeutics.

项目总结