A novel adenoviral vector-mediated mouse model of Charcot-Marie-Tooth type 2D (CMT2D)

Abstract

Charcot-Marie-Tooth disease type 2D is a hereditary axonal and glycyl-tRNA synthetase (GARS)-associated neuropathy that is caused by a mutation in GARS. Here, we report a novel GARS-associated mouse neuropathy model using an adenoviral vector system that contains a neuronal-specific promoter. In this model, we found that wild-type GARS is distributed to peripheral axons, dorsal root ganglion (DRG) cell bodies, central axon terminals, and motor neuron cell bodies. In contrast, GARS containing a G240R mutation was localized in DRG and motor neuron cell bodies, but not axonal regions, in vivo. Thus, our data suggest that the disease-causing G240R mutation may result in a distribution defect of GARS in peripheral nerves in vivo. Furthermore, a distributional defect may be associated with axonal degradation in GARS-associated neuropathies.

Novel animal models of GARS-associated neuropathy by overexpression of mutant GARS using an adenoviral vector

“…In previous studies, ATF3 activation by injurious stimuli was associated with deterioration of motor neurons (Tsujino et al 2000;Hai & Hartman 2001;Vlug et al 2005;de Waard et al 2010) and with cell death programs (Hai & Hartman 2001;Nakagomi et al 2003;Raivich et al 2004). In this animal model, ATF3 expression was increased in L129P mutant hGARS-expressing motor neurons compared with WT hGARS-expressing neurons; in addition, the regions near motor neurons in the L129P-expressing ventral horn were surrounded by more Iba1-positive microglial cells compared with the WT-expressing ventral horn (Seo et al 2014c). These results indicate that in dSMA-V, the expression of L129P mutant hGARS induces ATF3 activation in ventral motor neurons, and ATF3 activation triggers motor cell death programs through neuroinflammation mediated by microglia, similarly to the effects on ATF3 and microglia in ALS (Vlug et al 2005;Beers et al 2006;Boillée et al 2006;Yamanaka et al 2008).…”

“…An animal model incorporating an adenoviral vector system demonstrated that neuroinflammation is a potential mechanism underlying dSMA-V phenotypes (Seo et al 2014c). In previous studies, ATF3 activation by injurious stimuli was associated with deterioration of motor neurons (Tsujino et al 2000;Hai & Hartman 2001;Vlug et al 2005;de Waard et al 2010) and with cell death programs (Hai & Hartman 2001;Nakagomi et al 2003;Raivich et al 2004).…”

“…Animal models enable manifestation of morphological and functional phenotypes (Lee et al 2014;Seo et al 2014aSeo et al , 2014bSeo et al , 2014c. The promoter of the mouse choline acetyltransferase (ChAT) gene, which includes a neuron-restrictive silencer element and cholinergic-specific enhancer, key regulatory elements for neuron-specific expression, has been used in these models (Misawa et al 1992;Lönner-berg et al 1996).…”

“…The promoter of the mouse choline acetyltransferase (ChAT) gene, which includes a neuron-restrictive silencer element and cholinergic-specific enhancer, key regulatory elements for neuron-specific expression, has been used in these models (Misawa et al 1992;Lönner-berg et al 1996). Neuron-specific recombinant adenoviruses are injected into the sciatic nerve for anterograde and retrograde transduction (Lee et al 2014;Seo et al 2014aSeo et al , 2014bSeo et al , 2014c.…”

“…The ability of adenoviral vectors to deliver GARS mutants specifically into peripheral nerve axons has allowed experimental analysis of the pathological processes involved in the abnormal localization of GARS mutants (Seo et al 2014a(Seo et al , 2014b. In addition, the use of adenoviral vectors has led to the generation of GARS axonopathy animal models of neuropathic pain and motor impairment, which are symptoms in human patients (Lee et al 2014;Seo et al 2014c). Therefore, highly efficient adenoviral vectors for in vivo application in peripheral nerves offer an approach to overcome the limitations of using genetically modified transgenic mice, which lack specificity to long peripheral axons.…”