Regional Strain Pattern and Correlation with Cardiac Magnetic Resonance Imaging in Fabry Disease.

BACKGROUND: Cardiovascular disease is the most common cause of death among Fabry disease patients, who carry significantly increased risk for heart failure and sudden cardiac death. Echocardiographic strain imaging and cardiac MRI are important clinical tools for early detection of cardiomyopathy before onset of systolic or diastolic dysfunction. However, studies on these imaging modalities are limited among Fabry patients. AIM AND OBJECTIVE: To evaluate echocardiographic strain pattern and correlation with cardiac MRI in Fabry disease. MATERIALS AND METHODS: We performed a detailed analysis of global longitudinal strain and correlation with cardiac MRI finding in 9 patients diagnosed with Fabry disease. RESULTS: Despite normal left ventricular ejection fraction, basal and mid inferior segments are more likely to demonstrate strain abnormalities compared to other regions. Additionally, increased interventricular septal and left ventricular posterior wall thickness are correlated with greater strain abnormalities. Finally, MRI evidence of fibrosis and infiltration are detected among most patients with strain abnormalities, but in some cases, strain imaging were able to detect early evidence of cardiomyopathy even before MRI was fully able to detect the change. Basal and mid inferoseptal segment strain abnormalities are early signs of developing cardiomyopathy among patients with Fabry disease. CONCLUSION: Though cardiac MRIs are critical tools for detection of myocardial infiltration and scarring, these findings may not always be detectable in early phases of the disease. Multiple imaging modalities maybe considered in monitoring and evaluation of cardiomyopathy in Fabry disease.

Multisystem proteinopathy: Where myopathy and motor neuron disease converge.

Multisystem proteinopathy (MSP) is a pleiotropic group of inherited disorders that cause neurodegeneration, myopathy, and bone disease, and share common pathophysiology. Originally referred to as inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia (IBMPFD), attributed to mutations in the gene encoding valosin-containing protein (VCP), it has more recently been discovered that there are several other genes responsible for similar clinical and pathological phenotypes with muscle, brain, nerve, and bone involvement, in various combinations. These include heterogeneous nuclear ribonucleoprotein A2B1 and A1 (hnRNPA2B1, hnRNPA1), sequestosome 1 (SQSTM1), matrin 3 (MATR3), T-cell restricted intracellular antigen 1 (TIA1), and optineurin (OPTN), all of which share disruption of RNA stress granule function and autophagic degradation. This review will discuss each of the genes implicated in MSP, exploring the molecular pathogenesis, clinical features, current standards of care, and future directions for this diverse yet mechanistically linked spectrum of disorders.

Genetic Subtype-Phenotype Analysis of Growth Hormone Treatment on Psychiatric Behavior in Prader-Willi Syndrome.

Prader-Willi syndrome (PWS) is a complex multisystemic condition caused by a lack of paternal expression of imprinted genes from the 15q11.2-q13 region. Limited literature exists on the association between molecular classes, growth hormone use, and the prevalence of psychiatric phenotypes in PWS. In this study, we analyzed nine psychiatric phenotypes (depressed mood, anxiety, skin picking, nail picking, compulsive counting, compulsive ordering, plays with strings, visual hallucinations, and delusions) recognized in PWS and investigated associations with growth hormone treatment (GHT), deletions (DEL) and uniparental disomy (UPD) in a cohort of 172 individuals with PWS who met the criteria for analysis. Associations were explored using Pearson chi-square tests and univariable and multivariable logistic regression analyses to control for confounding exposures. This observational study of the largest dataset of patients with PWS to date suggested the following genetic subtype and phenotype correlations in psychiatric behaviors: (1) skin picking was more frequent in those with DEL vs. UPD; (2) anxiety was more common in those with UPD vs. DEL; and (3) an increased frequency of anxiety was noted in the UPD group treated with GHT compared to the DEL group. No other significant associations were found between the genetic subtype or GHT including for depressed mood, nail picking, compulsive counting, compulsive ordering, playing with strings, and visual hallucinations. Further studies will be required before any conclusions can be reached.

Molecular subtype and growth hormone effects on dysmorphology in Prader-Willi syndrome.

Prader-Willi syndrome (PWS) affects 1/15,000-1/30,000 live births and is characterized by lack of expression of paternally inherited genes on 15q11.2-15q13 caused by paternal deletions, maternal uniparental disomy (UPD), or imprinting defects. Affected individuals have distinct physical features, and growth hormone (GH) deficiency occurs in some individuals with PWS. The aim of this study is to test the hypotheses that (a) individuals with deletions and UPD have different physical and dysmorphic features, (b) individuals treated with GH have different physical and dysmorphic features than those not treated, and (c) GH treatment effects are different for individuals with UPD in comparison to those with deletions. Study participants included 30 individuals with deletions or UPD, who did or did not have GH treatment. Participants' molecular abnormalities were determined by molecular and cytogenetic analysis. Clinical data were obtained by a single dysmorphologist. Individuals with deletions were found to be heavier (p = .001), taller (p = .031), with smaller head circumferences (p = .042) and were more likely to have fair skin and hair than their family members (p = .031, .049, respectively) compared to UPD patients. Females with deletions more commonly had hypoplastic labia minora (p = .009) and clitoris (.030) in comparison to those with UPD. Individuals who received GH in both deletion and UPD groups were taller (p = .004), had larger hands (p = .011) and feet (p = .006) and a trend for a larger head circumference (p = .103). Interestingly, the GH-treated group also had a lower rate of strabismus (esotropia [p = .017] and exotropia [p = .039]). This study showed statistically significant correlations between phenotype and molecular subtypes and also between phenotype and GH treatment.

Early Diagnosis in Prader-Willi Syndrome Reduces Obesity and Associated Co-Morbidities.

Prader-Willi syndrome (PWS) is an imprinting genetic disorder characterized by lack of expression of genes on the paternal chromosome 15q11-q13 region. Growth hormone (GH) replacement positively influences stature and body composition in PWS. Our hypothesis was that early diagnosis delays onset of obesity in PWS. We studied 352 subjects with PWS, recruited from the NIH Rare Disease Clinical Research Network, to determine if age at diagnosis, ethnicity, gender, and PWS molecular class influenced the age they first become heavy, as determined by their primary care providers, and the age they first developed an increased appetite and began seeking food. The median ages that children with PWS became heavy were 10 years, 6 years and 4 years for age at diagnosis < 1 year, between 1 and 3 years, and greater than 3 years of age, respectively. The age of diagnosis and ethnicity were significant factors influencing when PWS children first became heavy (p < 0.01), however gender and the PWS molecular class had no influence. Early diagnosis delayed the onset of becoming heavy in individuals with PWS, permitting early GH and other treatment, thus reducing the risk of obesity-associated co-morbidities. Non-white individuals had an earlier onset of becoming heavy.

Impact of genetic subtypes of Prader-Willi syndrome with growth hormone therapy on intelligence and body mass index.

Prader-Willi syndrome (PWS) is a genomic imprinting disorder characterized by infantile hypotonia with a poor suck and failure to thrive, hypogenitalism/hypogonadism, behavior and cognitive problems, hormone deficiencies, hyperphagia, and obesity. The Stanford Binet and Wechsler (WAIS-R; WISC-III) intelligence (IQ) tests were administered on 103 individuals with PWS from two separate cohorts [University of California, Irvine (UCI) (N = 56) and Vanderbilt University (N = 47)] and clinical information obtained including growth hormone (GH) treatment, PWS molecular classes, weight and height. Significantly higher IQ scores (p < .02) were found representing the vocabulary section of the Stanford Binet test in the growth hormone (GH) treated group when compared with non-GH treatment in the pediatric-based UCI PWS cohort with a trend for stabilization of vocabulary IQ scores with age in the GH treated maternal disomy (UPD) 15 subject group. Significant differences (p = .05) were also found in the adult-based Vanderbilt PWS cohort with 15q11-q13 deletion subjects having lower Verbal IQ scores compared with UPD 15. No difference in body mass index was identified based on the PWS molecular class or genetic subtype. Medical care and response to treatment with growth hormone may influence intelligence impacted by PWS genetic subtypes and possibly age, but more studies are needed.

GAA variants and phenotypes among 1,079 patients with Pompe disease: Data from the Pompe Registry.

Identification of variants in the acid α-glucosidase (GAA) gene in Pompe disease provides valuable insights and systematic overviews are needed. We report on the number, nature, frequency, and geographic distribution of GAA sequence variants listed in the Pompe Registry, a long-term, observational program and the largest global repository of Pompe disease data. Variant information was reviewed and compared with publicly available GAA databases/resources. Among 1,079 eligible patients, 2,075 GAA variants (80 unique novel) were reported. Variants were listed by groups representing Pompe disease phenotypes. Patients were classified as Group A: Symptom onset ≤ 12 months of age with cardiomyopathy; Group B: Symptom onset ≤ 12 years of age (includes patients with symptom onset ≤ 12 months of age without cardiomyopathy); or Group C: Symptom onset > 12 years of age. Likely impact of novel variants was predicted using bioinformatics algorithms. Variants were classified by pathogenicity using ACMG guidelines. Data reported from the Pompe Registry provide new information about the distribution of GAA variants globally and across the clinical spectrum, add to the number and diversity of GAA variants registered in public databases through published data sharing, provide a first indication of the severity of novel variants, and assist in diagnostic practice and outcome prediction.

Homozygosity for the A431E mutation in PSEN1 presenting with a relatively aggressive phenotype.

OBJECTIVE: We report a 35 year-old male with childhood learning disability and early onset dementia who is homozygous for the A431E variant in the PSEN1 gene. Presenilin1 mutations are associated with autosomal dominant Alzheimer's dementia with young and somewhat stereotyped onset. Such variants may cause Alzheimer's dementia through aberrant processing of amyloid precursor protein through effects on γ-secretase activity. γ-secretase is involved in the cleavage of many proteins critical to normal function, including brain development. Therefore, manifestations in persons without normal Presenilin1 function is of interest. METHODS: Clinical evaluation including family history, examination, brain MRI, and genetic analysis. RESULTS: Our patient had mild developmental delay, chronic nighttime behavioral disturbance, and onset of progressive cognitive deficits at age 33. Clinical evaluation demonstrated spastic paraparesis and pseudobulbar affect. Brain MRI revealed cerebral atrophy disproportionate to age. Chronic microhemorrhages within bilateral occipital, temporal, and right frontal lobes were seen. Sanger sequencing confirmed homozygosity for the A431E variant in PSEN1, which is a known pathogenic variant causing autosomal dominant Alzheimer's dementia. CONCLUSIONS: Our report demonstrates that homozygosity for pathogenic Presenilin1 variants is compatible with life, though may cause a more aggressive phenotype with younger age of onset and possibly REM behavior disorder.

Contributing factors of mortality in Prader-Willi syndrome.

Prader-Willi syndrome (PWS) is a multi-system disorder resulting from a lack of paternal gene expression in the 15q11.2-q13 region. Using databases compiled through response questionnaires completed by families known to the Prader-Willi Syndrome Association (USA), this study tested the hypothesis that PWS genetic subtype, BMI, age of diagnosis, clinical symptoms, and growth hormone treatment differ among deceased and living individuals with PWS. Categorical and continuous variables were compared using chi-square and two-group t tests, respectively. Deceased individuals had higher rates of clinical features, including increased weight concerns, heart problems, sleep apnea, other respiratory complications, diabetes, osteoporosis, high pain tolerance, and severe skin picking, when compared to living individuals. Meanwhile, living individuals had higher rates of growth hormone use and early puberty. Obesity and subsequent consequences are the primary contributors to increased mortality in PWS. Additional emphasis on areas to decrease mortality is needed.

Pathogenic mutations in NUBPL affect complex I activity and cold tolerance in the yeast model Yarrowia lipolytica.

Complex I deficiency is a common cause of mitochondrial disease, resulting from mutations in genes encoding structural subunits, assembly factors or defects in mitochondrial gene expression. Advances in genetic diagnostics and sequencing have led to identification of several variants in NUBPL (nucleotide binding protein-like), encoding an assembly factor of complex I, which are potentially pathogenic. To help assign pathogenicity and learn more about the function of NUBPL, amino acid substitutions were recreated in the homologous Ind1 protein of the yeast model Yarrowia lipolytica. Leu102Pro destabilized the Ind1 protein, leading to a null-mutant phenotype. Asp103Tyr, Leu191Phe and Gly285Cys affected complex I assembly to varying degrees, whereas Gly136Asp substitution in Ind1 did not impact on complex I levels nor dNADH:ubiquinone activity. Blue-native polyacrylamide gel electrophoresis and immunolabelling of the structural subunits NUBM and NUCM revealed that all Ind1 variants accumulated a Q module intermediate of complex I. In the Ind1 Asp103Tyr variant, the matrix arm intermediate was virtually absent, indicating a dominant effect. Dysfunction of Ind1, but not absence of complex I, rendered Y. lipolytica sensitive to cold. The Ind1 Gly285Cys variant was able to support complex I assembly at 28°C, but not at 10°C. Our results indicate that Ind1 is required for progression of assembly from the Q module to the full matrix arm. Cold sensitivity could be developed as a phenotype assay to demonstrate pathogenicity of NUBPL mutations and other complex I defects.

Myogenic differentiation of VCP disease-induced pluripotent stem cells: A novel platform for drug discovery.

Valosin Containing Protein (VCP) disease is an autosomal dominant multisystem proteinopathy caused by mutations in the VCP gene, and is primarily associated with progressive muscle weakness, including atrophy of the pelvic and shoulder girdle muscles. Currently, no treatments are available and cardiac and respiratory failures can lead to mortality at an early age. VCP is an AAA ATPase multifunction complex protein and mutations in the VCP gene resulting in disrupted autophagic clearance. Due to the rarity of the disease, the myopathic nature of the disorder, ethical and practical considerations, VCP disease muscle biopsies are difficult to obtain. Thus, disease-specific human induced pluripotent stem cells (hiPSCs) now provide a valuable resource for the research owing to their renewable and pluripotent nature. In the present study, we report the differentiation and characterization of a VCP disease-specific hiPSCs into precursors expressing myogenic markers including desmin, myogenic factor 5 (MYF5), myosin and heavy chain 2 (MYH2). VCP disease phenotype is characterized by high expression of TAR DNA Binding Protein-43 (TDP-43), ubiquitin (Ub), Light Chain 3-I/II protein (LC3-I/II), and p62/SQSTM1 (p62) protein indicating disruption of the autophagy cascade. Treatment of hiPSC precursors with autophagy stimulators Rapamycin, Perifosine, or AT101 showed reduction in VCP pathology markers TDP-43, LC3-I/II and p62/SQSTM1. Conversely, autophagy inhibitors chloroquine had no beneficial effect, and Spautin-1 or MHY1485 had modest effects. Our results illustrate that hiPSC technology provide a useful platform for a rapid drug discovery and hence constitutes a bridge between clinical and bench research in VCP and related diseases.

Two cases of Legg-Perthes and intellectual disability in Tricho-Rhino-Phalangeal syndrome type 1 associated with novel TRPS1 mutations.

Tricho-Rhino-Phalangeal syndrome is a rare autosomal dominant genetic disorder caused by mutations in the TRPS1 gene. This malformation syndrome is characterized by distinctive craniofacial features including sparse scalp hair, bulbous tip of the nose, long flat philtrum, thin upper vermilion border, and protruding ears. Skeletal abnormalities include cone-shaped epiphyses at the phalanges, hip malformations, and short stature. In this report, we describe two patients with the physical manifestations and genotype of TRPS type I but with learning/intellectual disability not typically described as part of the syndrome. The first patient has a novel heterozygous two-base-pair deletion of nucleotides at 3198-3199 (c.3198-3199delAT) in the TRPS1 gene causing a translational frameshift and subsequent alternate stop codon. The second patient has a 3.08 million base-pair interstitial deletion at 8q23.3 (113,735,487-116,818,578), which includes the TRPS1 gene and CSMD3. Our patients have characteristic craniofacial features, Legg-Perthes syndrome, various skeletal abnormalities including cone shaped epiphyses, anxiety (first patient), and intellectual disability, presenting unusual phenotypes that add to the clinical spectrum of the disease.

Activation of the NLRP3 Inflammasome Is Associated with Valosin-Containing Protein Myopathy.

Aberrant activation of the NOD-like receptor (NLR) family, pyrin domain-containing protein 3 (NLRP3) inflammasome, triggers a pathogenic inflammatory response in many inherited neurodegenerative disorders. Inflammation has recently been associated with valosin-containing protein (VCP)-associated diseases, caused by missense mutations in the VCP gene. This prompted us to investigate whether NLRP3 inflammasome plays a role in VCP-associated diseases, which classically affects the muscles, bones, and brain. In this report, we demonstrate (i) an elevated activation of the NLRP3 inflammasome in VCP myoblasts, derived from induced pluripotent stem cells (iPSCs) of VCP patients, which was significantly decreased following in vitro treatment with the MCC950, a potent and specific inhibitor of NLRP3 inflammasome; (ii) a significant increase in the expression of NLRP3, caspase 1, IL-1ß, and IL-18 in the quadriceps muscles of VCPR155H/+ heterozygote mice, an experimental mouse model that has many clinical features of human VCP-associated myopathy; (iii) a significant increase of number of IL-1ß(+)F4/80(+)Ly6C(+) inflammatory macrophages that infiltrate the muscles of VCPR155H/+ mice; (iv) NLRP3 inflammasome activation and accumulation IL-1ß(+)F4/80(+)Ly6C(+) macrophages positively correlated with high expression of TDP-43 and p62/SQSTM1 markers of VCP pathology in damaged muscle; and (v) treatment of VCPR155H/+ mice with MCC950 inhibitor suppressed activation of NLRP3 inflammasome, reduced the F4/80(+)Ly6C(+)IL-1ß(+) macrophage infiltrates in the muscle, and significantly ameliorated muscle strength. Together, these results suggest that (i) NLRP3 inflammasome and local IL-1ß(+)F4/80(+)Ly6C(+) inflammatory macrophages contribute to pathogenesis of VCP-associated myopathy and (ii) identified MCC950 specific inhibitor of the NLRP3 inflammasome with promising therapeutic potential for the treatment of VCP-associated myopathy.

Prader-Willi Syndrome due to an Unbalanced de novo Translocation t(15;19)(q12;p13.3).

Prader-Willi syndrome (PWS) is a complex, multisystem genetic disorder characterized by endocrine, neurologic, and behavioral abnormalities. We report the first case of an unbalanced de novo reciprocal translocation of chromosomes 15 and 19, 45,XY,-15,der(19)t(15;19)(q12;p13.3), resulting in monosomy for the PWS critical chromosome region. Our patient had several typical features of PWS including infantile hypotonia, a poor suck and feeding difficulties, tantrums, skin picking, compulsions, small hands and feet, and food seeking, but not hypopigmentation, a micropenis, cryptorchidism or obesity as common findings seen in PWS at the time of examination at 6 years of age. He had seizures noted from 1 to 3 years of age and marked cognitive delay. High-resolution SNP microarray analysis identified an atypical PWS type I deletion in chromosome 15 involving the proximal breakpoint BP1. The deletion extended beyond the GABRB3 gene but was proximal to the usual distal breakpoint (BP3) within the 15q11q13 region, and GABRA5, GABRG3, and OCA2 genes were intact. No deletion of band 19p13.3 was detected; therefore, the patient was not at an increased risk of tumors from the Peutz-Jeghers syndrome associated with a deletion of the STK11 gene.

The Myoblast C2C12 Transfected with Mutant Valosin-Containing Protein Exhibits Delayed Stress Granule Resolution on Oxidative Stress.

Valosin-containing protein (VCP) mutations cause inclusion body myopathy with Paget disease and frontotemporal dementia. However, the mechanisms by which mutant VCP triggers degeneration remain unknown. Here, we investigated the role of VCP in cellular stress and found that the oxidative stressor arsenite and heat shock-activated stress responses evident by T-intracellular antigen-1-positive granules in C2C12 myoblasts. Granules also contained phosphorylated transactive response DNA-binding protein 43, ubiquitin, microtubule-associated protein 1A/1B light chains 3, and lysosome-associated membrane protein 2. Mutant VCP produced more T-intracellular antigen-1-positive granules than wild-type in the postarsenite exposure period. Similar results were observed for other granule components, indicating that mutant VCP delayed clearance of stress granules. Furthermore, stress granule resolution was impaired on differentiated C2C12 cells expressing mutant VCP. To address whether mutant VCP triggers dysregulation of the stress granule pathway in vivo, we analyzed skeletal muscle of aged VCPR155H-knockin mice. We found significant increments in oxidated proteins but observed the stress granule markers RasGAP SH3-binding protein and phosphorylated eukaryotic translation initiation factor 2α unchanged. The mixed results indicate that mutant VCP together with aging lead to higher oxidative stress in skeletal muscle but were insufficient to disrupt the stress granule pathway. Our findings support that deficiencies in recovery from stressors may result in attenuated tolerance to stress that could trigger muscle degeneration.

A Fine Balance of Dietary Lipids Improves Pathology of a Murine Model of VCP-Associated Multisystem Proteinopathy.

The discovery of effective therapies and of disease mechanisms underlying valosin containing protein (VCP)-associated myopathies and neurodegenerative disorders remains elusive. VCP disease, caused by mutations in the VCP gene, are a clinically and genetically heterogeneous group of disorders with manifestations varying from hereditary inclusion body myopathy, Paget's disease of bone, frontotemporal dementia (IBMPFD), and amyotrophic lateral sclerosis (ALS). In the present study, we examined the effects of higher dietary lipid percentages on VCPR155H/R155H, VCPR155H/+ and Wild Type (WT) mice from birth until 15 months of age by immunohistochemical and biochemical assays. Findings illustrated improvement in the muscle strength, histology, and autophagy signaling pathway in the heterozygote mice when fed 9% lipid-enriched diets (LED). However, increasing the LED by 12%, 30%, and 48% showed no improvement in homozygote and heterozygote survival, muscle pathology, lipid accumulation or the autophagy cascade. These findings suggest that a balanced lipid supplementation may have a therapeutic strategy for patients with VCP-associated multisystem proteinopathies.

Clinical characterization of int22h1/int22h2-mediated Xq28 duplication/deletion: new cases and literature review.

BACKGROUND: Int22h1/int22h2-mediated Xq28 duplication syndrome is caused by ~0.5 Mb chromosomal duplications mediated by nonallelic homologous recombination between intron 22 homologous region 1 (int22h1) and 2 (int22h2), which, in addition to int22h3, are also responsible for inversions disrupting the F8 gene in hemophilia A. This syndrome has recently been described in 9 males with cognitive impairment, behavioral problems, and distinctive facial features; and 6 females with milder phenotypes. The reciprocal deletion was previously reported in a mother and daughter. It was suggested that this deletion may not have phenotypic effects in females because of skewed chromosome X inactivation, but may be embryonic lethal in males. METHODS: Array comparative genomic hybridization analyses were performed using oligonucleotide-based chromosomal microarray. Chromosome X inactivation studies were performed at the AR (androgen receptor) and FMR1 (fragile X mental retardation 1) loci. RESULTS: We present here 5 males and 6 females with int22h1/int22h2-mediated Xq28 duplication syndrome. The males manifested cognitive impairment, behavioral problems, and distinctive facial features. Two of the six females manifested mild cognitive impairment. This duplication was maternally inherited, and skewed chromosome X inactivation was observed in the majority of females carrying the duplication. We also report the reciprocal deletion in a mother and daughter with overweight, but normal cognition. In addition, we present the first case of a prenatally diagnosed de novo int22h1/int22h2-mediated deletion in a healthy female infant. We reviewed individuals previously reported with similar or overlapping rearrangements and evaluated the potential roles of genes in the rearrangement region. CONCLUSIONS: The similarity of clinical features among individuals with the int22h1/int22h2-mediated Xq28 duplication supports the notion that this duplication causes a recognizable syndrome that affects males with females exhibiting milder phenotypes. It is suggested that the observed cognitive impairment in this syndrome results from increased dosage of RAB39B gene located within the duplicated region. Increased dosage of CLIC2 may also contribute to the phenotype. The reciprocal deletion results in skewed chromosome X inactivation and no clinical phenotype in females. Review of overlapping deletions suggests that hemizygous loss of VBP1 may be the cause for the proposed male lethality associated with this deletion.

Rapamycin and chloroquine: the in vitro and in vivo effects of autophagy-modifying drugs show promising results in valosin containing protein multisystem proteinopathy.

Mutations in the valosin containing protein (VCP) gene cause hereditary Inclusion body myopathy (hIBM) associated with Paget disease of bone (PDB), frontotemporal dementia (FTD), more recently termed multisystem proteinopathy (MSP). Affected individuals exhibit scapular winging and die from progressive muscle weakness, and cardiac and respiratory failure, typically in their 40s to 50s. Histologically, patients show the presence of rimmed vacuoles and TAR DNA-binding protein 43 (TDP-43)-positive large ubiquitinated inclusion bodies in the muscles. We have generated a VCPR155H/+ mouse model which recapitulates the disease phenotype and impaired autophagy typically observed in patients with VCP disease. Autophagy-modifying agents, such as rapamycin and chloroquine, at pharmacological doses have previously shown to alter the autophagic flux. Herein, we report results of administration of rapamycin, a specific inhibitor of the mechanistic target of rapamycin (mTOR) signaling pathway, and chloroquine, a lysosomal inhibitor which reverses autophagy by accumulating in lysosomes, responsible for blocking autophagy in 20-month old VCPR155H/+ mice. Rapamycin-treated mice demonstrated significant improvement in muscle performance, quadriceps histological analysis, and rescue of ubiquitin, and TDP-43 pathology and defective autophagy as indicated by decreased protein expression levels of LC3-I/II, p62/SQSTM1, optineurin and inhibiting the mTORC1 substrates. Conversely, chloroquine-treated VCPR155H/+ mice revealed progressive muscle weakness, cytoplasmic accumulation of TDP-43, ubiquitin-positive inclusion bodies and increased LC3-I/II, p62/SQSTM1, and optineurin expression levels. Our in vitro patient myoblasts studies treated with rapamycin demonstrated an overall improvement in the autophagy markers. Targeting the mTOR pathway ameliorates an increasing list of disorders, and these findings suggest that VCP disease and related neurodegenerative multisystem proteinopathies can now be included as disorders that can potentially be ameliorated by rapalogs.

In vitro studies in VCP-associated multisystem proteinopathy suggest altered mitochondrial bioenergetics.

Mitochondrial dysfunction has recently been implicated as an underlying factor to several common neurodegenerative diseases, including Parkinson's disease, Alzheimer's and amyotrophic lateral sclerosis (ALS). Valosin containing protein (VCP)-associated multisystem proteinopathy is a new hereditary disorder associated with inclusion body myopathy, Paget disease of bone (PDB), frontotemporal dementia (FTD) and ALS. VCP has been implicated in several transduction pathways including autophagy, apoptosis and the PINK1/Parkin cascade of mitophagy. In this report, we characterized VCP patient and mouse fibroblasts/myoblasts to examine their mitochondrial dynamics and bioenergetics. Using the Seahorse XF-24 technology, we discovered decreased spare respiratory capacity (measurement of extra ATP that can be produced by oxidative phosphorylation in stressful conditions) and increased ECAR levels (measurement of glycolysis), and proton leak in VCP human fibroblasts compared with age- and sex-matched unaffected first degree relatives. We found decreased levels of ATP and membrane potential, but higher mitochondrial enzyme complexes II+III and complex IV activities in the patient VCP myoblasts when compared to the values of the control cell lines. These results suggest that mutations in VCP affect the mitochondria's ability to produce ATP, thereby resulting in a compensatory increase in the cells' mitochondrial complex activity levels. Thus, this novel in vitro model may be useful in understanding the pathophysiology and discovering new drug targets of mitochondrial dynamics and physiology to modify the clinical phenotype in VCP and related multisystem proteinopathies (MSP).

Administration of CoQ10 analogue ameliorates dysfunction of the mitochondrial respiratory chain in a mouse model of Angelman syndrome.

Genetic defects in the UBE3A gene, which encodes for the imprinted E6-AP ubiquitin E3 ligase (UBE3A), is responsible for the occurrence of Angelman syndrome (AS), a neurodegenerative disorder which arises in 1 out of every 12,000-20,000 births. Classical symptoms of AS include delayed development, impaired speech, and epileptic seizures with characteristic electroencephalography (EEG) readings. We have previously reported impaired mitochondrial structure and reduced complex III in the hippocampus and cerebellum in the Ube3a(m-/p+) mice. CoQ10 supplementation restores the electron flow to the mitochondrial respiratory chain (MRC) to ultimately increase mitochondrial antioxidant capacity. A number of recent studies with CoQ10 analogues seem promising in providing therapeutic benefit to patients with a variety of disorders. CoQ10 therapy has been reported to be safe and relatively well-tolerated at doses as high as 3000mg/day in patients with disorders of CoQ10 biosynthesis and MRC disorders. Herein, we report administration of idebenone, a potent CoQ10 analogue, to the Ube3a(m-/p+) mouse model corrects motor coordination and anxiety levels, and also improves the expression of complexes III and IV in hippocampus CA1 and CA2 neurons and cerebellum in these Ube3a(m-/p+) mice. However, treatment with idebenone illustrated no beneficial effects in the reduction of oxidative stress. To our knowledge, this is the first study to suggest an improvement in mitochondrial respiratory chain dysfunction via bioenergetics modulation with a CoQ10 analogue. These findings may further elucidate possible cellular and molecular mechanism(s) and ultimately a clinical therapeutic approach/benefit for patients with Angelman syndrome.