Targeted Excision of VCP R155H Mutation by Cre-LoxPTechnology as a Promising Therapeutic Strategy for Valosin-Containing Protein Disease

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.

215th ENMC International Workshop VCP-related multi-system proteinopathy (IBMPFD) 13–15 November 2015, Heemskerk, The Netherlands

“…There is insufficient information about the incidence and prevalence, genotype–phenotype correlations, penetrance, natural history and causes of death in IBMPFD. Currently, there is no known specific treatment for IBMPFD, and even though there are some interesting leads from animal studies [4–6] there are no established patient cohorts and outcome measures to test these compounds/approaches in appropriate clinical trials.…”

“…Histologically, the uphill exercised VCP R155H/+ mice displayed an improvement in muscle atrophy, and decreased expression levels of ubiquitin, P62/ SQSTM1 , LC3I/II, and TDP-43 autophagy markers, suggesting an alleviation of disease-induced myopathy phenotypes. In contrast, mice exercised to run downhill did not show any improvement [4]. Targeted excision of the p.R155H mutation in VCP mice using Cre-ER ™ -VCP R155H/+ technology demonstrated improved muscle strength and quadriceps fibre architecture, reduced expression of autophagy markers, reduced brain neuropathology, decreased apoptosis, and improvement of the Paget-like bone changes [4].…”

“…In contrast, mice exercised to run downhill did not show any improvement [4]. Targeted excision of the p.R155H mutation in VCP mice using Cre-ER ™ -VCP R155H/+ technology demonstrated improved muscle strength and quadriceps fibre architecture, reduced expression of autophagy markers, reduced brain neuropathology, decreased apoptosis, and improvement of the Paget-like bone changes [4]. This finding provides proof of principle that other allele silencing or downregulating technologies may be useful therapies in patients.…”

Emerging role of VCP/p97 in cardiovascular diseases: novel insights and therapeutic opportunities

“…Additionally, adenine nucleotide transferase is dysregulated due to pathogenic mutations involving VCP/p97 , resulting in reduced ATP levels [ 20 ]. Utilization of the Cre-LoxP technology for excision of the VCP/p97 R155H missense mutation was anticipated as a correctional approach for this mutation [ 21 ], but currently there are no effective treatments for these genetic mutations.…”

VCP/p97 inhibitor CB-5083 modulates muscle pathology in a mouse model of VCP inclusion body myopathy

“…In vitro analysis of VCP mutants has shown pathologically enhanced ATPase enzymatic activity [ 14 – 16 ]. Additionally, excision of the mutant allele in the heterozygous mouse model of VCP disease, which contains the most common patient-specific mutation R155H, has been shown to improve the disease pathology [ 17 ]. Recent studies in drosophila models carrying gain of function pathogenic VCP mutations have shown severe mitochondrial fusion defects, and increased degradation of mitofusins (MFN1 and MFN2) [ 18 ].…”