Mice homozygous for c.451C>T mutation in Cln1 gene recapitulate INCL phenotype. (18th November 2014)

• Record Type: Journal Article
• Authors: Bouchelion, Ashleigh; Zhang, Zhongjian; Li, Yichao; Qian, Haohua; Mukherjee, Anil B.
• Is Part Of: Annals of clinical and translational neurology. Volume 1:Number 12(2014)
• Page Start: 1006
• Page End: 1023
• Publication Date: 2014-11-18
• Subjects: Nervous system -- Diseases -- Periodicals; Neurology -- Periodicals; 616.8005
• DOI: 10.1002/acn3.144
• Languages: English
• ISSNs: 2328-9503

Abstract

<abstract abstract-type="main" id="acn3144-abs-0001"> <title>Abstract</title> <sec id="acn3144-sec-0001" sec-type="section"> <title>Objective</title> <p>Nonsense mutations account for 5–70% of all genetic disorders. In the United States, nonsense mutations in the <italic>CLN1/PPT1</italic> gene underlie >40% of the patients with infantile neuronal ceroid lipofuscinosis (INCL), a devastating neurodegenerative lysosomal storage disease. We sought to generate a reliable mouse model of INCL carrying the most common <italic>Ppt1</italic> nonsense mutation (c.451C>T) found in the United States patient population to provide a platform for evaluating nonsense suppressors in vivo.</p> </sec> <sec id="acn3144-sec-0002" sec-type="section"> <title>Methods</title> <p>We knocked‐in c.451C>T nonsense mutation in the <italic>Ppt1</italic> gene in C57 embryonic stem (ES) cells using a targeting vector in which LoxP flanked the Neo cassette, which was removed from targeted ES cells by electroporating <italic>Cre</italic>. Two independently targeted ES clones were injected into blastocysts to generate syngenic C57 knock‐in mice, obviating the necessity for extensive backcrossing.</p> </sec> <sec id="acn3144-sec-0003" sec-type="section"> <title>Results</title> <p>Generation of <italic>Ppt1</italic>‐KI mice was confirmed by DNA sequencing, which showed the presence of c.451C>T mutation in the <italic>Ppt1</italic> gene. These mice are viable and fertile, although they developed spasticity (a "clasping" phenotype) at a median age of 6 months. Autofluorescent storage materials accumulated throughout the brain regions and in visceral organs. Electron microscopic analysis of the brain and the spleen showed granular osmiophilic deposits. Increased neuronal apoptosis was particularly evident in cerebral cortex and abnormal histopathological and electroretinographic (ERG) analyses attested striking retinal degeneration. Progressive deterioration of motor coordination and behavioral parameters continued until eventual death.</p> </sec> <sec id="acn3144-sec-0004" sec-type="section"> <title>Interpretation</title> <p>Our findings show that <italic>Ppt1</italic>‐KI mice reliably recapitulate INCL phenotype providing a platform for testing the efficacy of existing and novel nonsense suppressors in vivo.</p> </sec> </abstract>