Targeted excision of VCP R155H mutation by Cre-LoxP technology as a promising therapeutic strategy for valosin-containing protein disease.

Angèle Nalbandian,Edward S Monuki,Virginia E Kimonis,Christopher Nguyen,Katrina J Llewellyn

doi:10.1089/hgtb.2014.096

Angèle Nalbandian, Edward S Monuki + Show 3 more

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https://doi.org/10.1089/hgtb.2014.096

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Abstract

Inclusion body myopathy associated with Paget's disease of the bone and frontotemporal dementia is attributed to mutations in the valosin-containing protein (VCP) gene, mapped to chromosomal region 9p13.3-12. Affected individuals exhibit scapular winging and die from progressive muscle weakness and cardiac and respiratory failure in their 40s to 50s. Mutations in the VCP gene have also been associated with amyotrophic lateral sclerosis in 10-15% of individuals with hereditary inclusion body myopathy and 2-3% of isolated familial amyotrophic lateral sclerosis. Currently, there are no effective treatments for VCP-related myopathy or dementia. To determine the effects of targeted excision of the most common R155H mutation in VCP disease, we generated the Cre-ER™-VCPR155H/+ tamoxifen-inducible model. We administered tamoxifen (0.12 mg/g body weight) or corn oil (vehicle) to the pregnant dams by oral gavage and monitored survival and muscle strength measurements of the pups until 18 months of age. We confirmed efficient removal of exons 4 and 5 and recombination of the mutant/floxed VCP copies by Q-PCR analyses. The activity and specificity of Cre recombinase was confirmed by immunostaining. Herein, we report that Cre-ER™-VCPR155H/+ mice demonstrated improved muscle strength and quadriceps fibers architecture, autophagy signaling pathway, reduced brain neuropathology, decreased apoptosis, and less severe Paget-like bone changes. The Cre-ER™-VCPR155H/+ mouse model provides proof of principle by demonstrating that removal of the mutated exons could be beneficial to patients with VCP-related neurodegenerative diseases, and serves as an excellent platform in understanding the underlying pathophysiological mechanism(s) in the hopes of a promising therapeutic approach.

Highlights

Inclusion body myopathy associated with Paget’s disease of the bone (PDB) and frontotemporal dementia (OMIM 167320) was first reported in 2000 by Kimonis et al.,[1] mapped to the human chromosomal region 9p13.3– 12.2,3 In 2004, the disease was attributed to being caused by mutations in the gene encoding valosin-containing protein (VCP).[4]
The VCPR155H/ + heterozygous mouse was created with two loxp sites, placed on either side of the R155H mutation in exons 4 and 5, allowing the possibility of deleting this region, thereby knocking the mutant allele out of frame, with Cre-loxP technology.[33]
The rationale for deletion of exons 4 and 5 was to disrupt the mutant VCP open reading frame, thereby leaving the normal allele intact, providing proof of principle that removal of the mutated gene could result in amelioration of muscle pathology (Fig. 1a)

Summary

Introduction

Inclusion body myopathy associated with Paget’s disease of the bone (PDB) and frontotemporal dementia (OMIM 167320) was first reported in 2000 by Kimonis et al.,[1] mapped to the human chromosomal region 9p13.3– 12.2,3 In 2004, the disease was attributed to being caused by mutations in the gene encoding valosin-containing protein (VCP).[4] Classic symptoms of VCP disease include weakness and atrophy of the pelvic and shoulder girdle muscles in 90% of individuals.[1,2,3] Affected individuals exhibit scapular winging and die from progressive muscle weakness, and cardiac and respiratory failure, typically in their 40s to 50s.1,5. Classic symptoms of VCP disease include weakness and atrophy of the pelvic and shoulder girdle muscles in 90% of individuals.[1,2,3] Affected individuals exhibit scapular winging and die from progressive muscle weakness, and cardiac and respiratory failure, typically in their 40s to 50s.1,5 Histologically, patients show the presence of rimmed vacuoles and TAR DNA-binding protein 43 (TDP-43)-positive ubiquitinated inclusion bodies in the muscles.[1,4,5,6] The variable phenotype is often diagnosed as limb girdle muscular dystrophy, amyotrophic lateral sclerosis (ALS), facioscapular muscular dystrophy, or scapuloperoneal muscular dystrophy.[5,7,8]

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