A genetic model of amyotrophic lateral sclerosis in zebrafish displays phenotypic hallmarks of motoneuron disease

Abstract

SUMMARYAmyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that, for ~80% of patients, is fatal within five years of diagnosis. To better understand ALS, animal models have been essential; however, only rodent models of ALS exhibit the major hallmarks of the disease. Here, we report the generation of transgenic zebrafish overexpressing mutant Sod1. The construct used to generate these lines contained the zebrafish sod1 gene and ~16 kb of flanking sequences. We generated lines expressing the G93R mutation, as well as lines expressing wild-type Sod1. Focusing on two G93R lines, we found that they displayed the major phenotypes of ALS. Changes at the neuromuscular junction were observed at larval and adult stages. In adulthood the G93R mutants exhibited decreased endurance in a swim tunnel test. An analysis of muscle revealed normal muscle force, however, at the end stage the fish exhibited motoneuron loss, muscle atrophy, paralysis and premature death. These phenotypes were more severe in lines expressing higher levels of mutant Sod1 and were absent in lines overexpressing wild-type Sod1. Thus, we have generated a vertebrate model of ALS to complement existing mammal models.

Atomic structure of a toxic, oligomeric segment of SOD1 linked to amyotrophic lateral sclerosis (ALS)

“…To determine whether corkscrew-disrupting mutations alleviate axonopathies caused by familial SOD1 mutants in vivo, we conducted experiments using a zebrafish model of ALS (37)(38)(39)(40). We expressed A4V SOD1 with and without the corkscrew-disrupting substitution at Gly33 in a zebrafish TDL6 line in which the primary motor neurons are labeled with GFP and the mitochondria are labeled with dsRed (41).…”

Deficiency in the mRNA export mediator Gle1 impairs Schwann cell development in the zebrafish embryo

“…T h e z e b r a f i s h h a s b e e n e x t e n s i v e l y u s e d a s a m o d e l organism for neurodegenerative disorders (for review see (Kabashi et al, 2010, Xi et al, 2011), including models of motor neuron diseases such as SMA (Boon et al, 2009) and ALS (Ramesh et al, 2010). A zebrafish model of LCCS1 has recently been reported, with gle1 -/-embryos showing multiple defects, including immobility, small eyes, pharyngeal arch defects, CNS cell death, a moderate reduction in motor neuron numbers and motor axon outgrowth defects (Jao et al, 2012).…”

Mitophagy and neurodegeneration

“…20 Several neurodegenerative diseases have been modeled in zebrafish by expressing mutant forms of the human disease gene under the control of a zebrafish promoter. Examples of these genes include MAPT, 21,22 SOD1, 23 and HTT. 24 Fusion of green fluorescent protein (GFP) to the disease-causing transgene can be used to monitor the clearance of protein aggregates, 24 and a similar approach of fluorescently tagging mitochondrial proteins can be used to monitor mitophagy in an intact organism under a variety of conditions.…”