Valosin-containing protein immunoreactivity in tauopathies, synucleinopathies, polyglutamine diseases and intranuclear inclusion body disease

Ribosomal protein SA is a common component of neuronal intranuclear inclusions in polyglutamine diseases and Marinesco bodies

Neuronal intranuclear inclusions (NIIs) are common key structures in polyglutamine (polyQ) diseases such as Huntington disease (HD), spinocerebellar ataxia type 1 (SCA1), and SCA3. Marinesco bodies (MBs) of dopaminergic neurons in the substantia nigra are also intranuclear structures and are frequently seen in normal elderly people. Ribosomal dysfunction is closely related to two differential processes; therefore, we aimed to identify the pathological characteristics of ribosomal protein SA (RPSA), a ribosomal protein, in both states. To this end, we evaluated the autopsy findings in four patients with HD, two SCA3, and five normal elderly cases (NCs). Immunohistochemical studies demonstrated that both NIIs and MBs contain RPSA. In polyQ diseases, RPSA was co-localized with polyQ aggregations, and 3D-reconstructed images revealed their mosaic-like distribution. Assessments of the organization of RPSA and p62 in NIIs showed that RPSA was more localized toward the center than p62 and that this unique organization was more evident in the MBs. Immunoblotting of the temporal cortices revealed that the nuclear fraction of HD patients contained more RPSA than that of NCs. In conclusion, our study revealed that RPSA is a common component of both NIIs and MBs, indicating that a similar mechanism contributes to the formation of polyQ NIIs and MBs.

Valosin containing protein (VCP): initiator, modifier, and potential drug target for neurodegenerative diseases

The AAA+ ATPase valosin containing protein (VCP) is essential for cell and organ homeostasis, especially in cells of the nervous system. As part of a large network, VCP collaborates with many cofactors to ensure proteostasis under normal, stress, and disease conditions. A large number of mutations have revealed the importance of VCP for human health. In particular, VCP facilitates the dismantling of protein aggregates and the removal of dysfunctional organelles. These are critical events to prevent malfunction of the brain and other parts of the nervous system. In line with this idea, VCP mutants are linked to the onset and progression of neurodegeneration and other diseases. The intricate molecular mechanisms that connect VCP mutations to distinct brain pathologies continue to be uncovered. Emerging evidence supports the model that VCP controls cellular functions on multiple levels and in a cell type specific fashion. Accordingly, VCP mutants derail cellular homeostasis through several mechanisms that can instigate disease. Our review focuses on the association between VCP malfunction and neurodegeneration. We discuss the latest insights in the field, emphasize open questions, and speculate on the potential of VCP as a drug target for some of the most devastating forms of neurodegeneration.

An autopsy case of amyotrophic lateral sclerosis with striatonigral and pallidoluysian degeneration and cat's-eye-shaped neuronal nuclear inclusions

We report the case of a Japanese woman with sporadic amyotrophic lateral sclerosis (ALS) of 28 months' duration who died at the age of 66 years. Postmortem examination revealed moderate loss of neurons and phosphorylated TDP-43 (p-TDP-43)-immunoreactive neuronal and glial cytoplasmic inclusions in the upper and lower motor neurons. Additionally, marked neuronal loss was observed in the neostriatum, globus pallidum, subthalamic nucleus, and substantia nigra. p-TDP-43-immunoreactive inclusions were frequently found in these areas. Neuronal loss and TDP-43 pathology in the motor, striatonigral, and pallidoluysian systems were predominant on the right side. Moreover, p-TDP-43-immunoreactive cat's-eye-shaped neuronal nuclear inclusions (NNIs) were observed in the affected lesions. NNIs in the striatonigral system were also positive for valosin-containing protein (VCP). We diagnosed the patient as having ALS with striatonigral and pallidoluysian degeneration. Patients with ALS rarely experience pallido-nigro-luysian degeneration. To our best knowledge, only one case of ALS combined with striatonigral and pallidoluysian degeneration has been reported. Neuronal loss in the striatonigral and/or pallidoluysian systems has also been reported in patients with ALS with multisystem degeneration accompanied by long-term use of an artificial respirator. Based on these findings, a possibility of an extremely rare subtype of ALS demonstrating selective loss of neurons in the striatonigral and pallidoluysian systems exists; another possibility is that this type could be an early stage or forme fruste of ALS with multisystem degeneration. Although VCP-positive cat's-eye-shaped NNIs have been reported in spinocerebellar ataxia type-2 cases, our case report presents VCP-positive NNIs in a patient with ALS for the first time.

The clinical and neuropathological picture of adult neuronal intranuclear inclusion disease with no radiological abnormality

In typical adult neuronal intranuclear inclusion disease (NIID) with predilection for the basal ganglia or cerebral cortex, not only neurons but also glial cells harbor intranuclear inclusions. In addition, these inclusions are present in the peripheral autonomic nervous system, visceral organs and skin. In NIID cases with an expansion of GGC repeats in the 5'-untranslated region (5'-UTR) of the Notch 2 N-terminal like C (NOTCH2NLC) gene, these repeats are located in an upstream open reading frame (uN2C) and result in the production of a polyglycine-containing protein called uN2CpolyG. Typically, patients with adult NIID show high-intensity signals at the corticomedullary junction on diffusion-weighted brain magnetic resonance imaging. We report a case of adult NIID in a 78-year-old Japanese male, who suffered from mild, non-progressive tremor during life but showed no radiographic abnormalities suggestive of adult NIID. Pathologically, ubiquitin-, p62- and uN2CpolyG-positive neuronal intranuclear inclusions were particularly frequent in the hippocampal formation, but were also seen in the enteric plexuses, kidney and cardiac muscles. By contrast, glial intranuclear inclusions were barely evident in the affected regions. The present case also had an immunohistochemical profile differing from that of typical adult NIID. The findings in this case suggest that adult NIID can show clinical, radiographic and pathological heterogeneity.

CRISPR/Cas9-engineered Drosophila knock-in models to study VCP diseases

Mutations in Valosin Containing Protein (VCP) are associated with several degenerative diseases, including multisystem proteinopathy (MSP-1) and amyotrophic lateral sclerosis. However, patients with VCP mutations vary widely in their pathology and clinical penetrance, making it difficult to devise effective treatment strategies. A deeper understanding of how each mutation affects VCP function could enhance the prediction of clinical outcomes and design of personalized treatment options. The power of a genetically tractable model organism coupled with well-established in vivo assays and a relatively short life cycle make Drosophila an attractive system to study VCP disease pathogenesis. Using CRISPR/Cas9, we have generated individual Drosophila knock-in mutants that include nine hereditary VCP disease mutations. Our models display many hallmarks of VCP-mediated degeneration, including progressive decline in mobility, protein aggregate accumulation and defects in lysosomal and mitochondrial function. We also made some novel and unexpected findings, including nuclear morphology defects and sex-specific phenotypic differences in several mutants. Taken together, the Drosophila VCP disease models generated in this study will be useful for studying the etiology of individual VCP patient mutations and testing potential genetic and/or pharmacological therapies.

Identification of GGC repeat expansion in the NOTCH2NLC gene in amyotrophic lateral sclerosis

OBJECTIVE

To determine whether the GGC repeats in the NOTCH2NLC gene contribute to amyotrophic lateral sclerosis (ALS).

METHODS

In this study, 545 patients with ALS and 1,305 healthy controls from mainland China were recruited. Several pathogenic mutations in known ALS-causative genes (including C9ORF72 and ATXN2) and polynucleotide repeat expansions in NOP56 and AR genes were excluded. Repeat-primed PCR and GC-rich PCR were performed to determine the GGC repeat size in NOTCH2NLC. Systematic and targeted clinical evaluations and investigations, including skin biopsy and dynamic electrophysiologic studies, were conducted in the genetically affected patients.

RESULTS

GGC repeat expansion was observed in 4 patients (numbers of repeats 44, 54, 96, and 143), accounting for ≈0.73% (4 of 545) of all patients with ALS. A comparison with 1,305 healthy controls revealed that GGC repeat expansion in NOTCH2NLC was associated with ALS (Fisher exact test, 4 of 545 vs 0 of 1,305, p = 0.007). Compared to patients with the neuronal intranuclear inclusion disease (NIID) muscle weakness-dominant subtype, patients with ALS phenotype carrying the abnormal repeat expansion tended to have a severe phenotype and rapid deterioration.

CONCLUSION

Our results suggest that ALS is a specific phenotype of NIID or that GGC expansion in NOTCH2NLC is a factor that modifies ALS. These findings may help clarify the pathogenic mechanism of ALS and may expand the known clinical spectrum of NIID.

Genes, the brain, and artificial intelligence in evolution

Three important systems, genes, the brain, and artificial intelligence (especially deep learning) have similar goals, namely, the maximization of likelihood or minimization of cross-entropy. Animal brains have evolved through predator-prey interactions in which maximizing survival probability and transmission of genes to offspring were the main objectives. Coordinate transformation for a rigid body necessary to win predator-prey battles requires a huge amount of matrix operations in the brain similar to those performed by a powerful GPU. Things (molecules), information (genes), and energy (ATP) are essential for using Maxwell's demon model to understand how a living system maintains a low level of entropy. However, while the history of medicine and biology saw molecular biology and genetics disciplines flourish, the study of energy has been limited, despite estimates that >10% all human genes code energy-related proteins. Since there are a large number of molecular and genetic diseases, many energy-related diseases must exist as well. In addition to mitochondrial disease, common diseases such as neurodegenerative diseases, muscle diseases, cardiomyopathy, and diabetes are candidates for diseases related to cellular energy shortage. We are developing ATP enhancer, a drug to treat such diseases. I predict that in the future, the frontier of medicine and biology will involve energy and entropy, and the frontier of science will be about the cognitive processes that scientists' brains use to study mathematics and physics. That will be understood by comparing the abilities that were necessary to survive battles between predators and prey during evolutionary history.

Marinesco bodies and substantia nigra neuron density in Parkinson's disease

AIM

Marinesco bodies (MB) are intranuclear inclusions in pigmented neurons of the substantia nigra (SN). While rare in children, frequency increases with normal ageing and is high in Alzheimer's disease, dementia with Lewy bodies and other neurodegenerative disorders. Coinciding with the age-related rise in MB frequency is initiation of cell death among SN neurons. Whether MB have a role in this process is unknown. Our aim is to examine the association of MB with SN neuron density in Parkinson's disease (PD) in the Honolulu-Asia Aging Study.

METHODS

Data on MB and neuron density were measured in SN transverse sections in 131 autopsied men aged 73-99 years at the time of death from 1992 to 2007.

RESULTS

Marinesco body frequency was low in the presence vs. absence of PD (2.3% vs. 6.6%, P < 0.001). After PD onset, MB frequency declined as duration of PD increased (P = 0.006). Similar patterns were observed for SN neuron density. When MB frequency was low, neuron density was noticeably reduced in the SN ventrolateral quadrant, the region most vulnerable to PD neurodegeneration. Low MB frequency was unique to PD as its high frequency in non-PD cases was unrelated to parkinsonian signs and incidental Lewy bodies. Frequency was high in the presence of Alzheimer's disease and apolipoprotein ε4 alleles.

CONCLUSIONS

While findings confirm that MB frequency is low in PD, declines in MB frequency continue with PD duration. The extent to which MB have a distinct relationship with PD warrants clarification. Further studies of MB could be important in understanding PD processes.

Adult-onset neuronal intranuclear hyaline inclusion disease is not rare in older adults

Neuronal intranuclear hyaline inclusion disease (NIHID) is a rare neurodegenerative disorder pathologically characterized by localized neuronal loss, and the presence of eosinophilic intranuclear inclusions in neurons and glial cells. NIHID is a heterogeneous disease entity. It is divided into three clinical subgroups: infantile, juvenile and adult forms. Recently, reports of adult-onset cases have increased. Typical adult-onset NIHID consists of cognitive dysfunction with leukoencephalopathy. This type of adult-onset NIHID can be predicted by characteristic magnetic resonance images, high intensity areas on T2-weighted/fluid-attenuated inversion recovery images and persistent high intensity at the corticomedullary junction in diffusion-weighted images. When clinically suspected, the ante-mortem diagnosis can be made by biopsy. In adult-onset NIHID, nuclear inclusions are found more frequently in glial cells, and moderate to severe white matter degeneration is often associated. Although the underlying pathological mechanisms of NIHID are largely unknown, abnormal intranuclear accumulations of proteins and/or dysfunction of protein degradation systems might be related to the pathogenesis. To further clarify the characteristics of this disease entity, biological and pathological analysis of the patients is indispensable. As this disease entity becomes better known, diagnosed cases are expected to increase. Adult-onset NIHID might not be as extremely rare as previously thought.

VCP recruitment to mitochondria causes mitophagy impairment and neurodegeneration in models of Huntington's disease

Mutant Huntingtin (mtHtt) causes neurodegeneration in Huntington's disease (HD) by evoking defects in the mitochondria, but the underlying mechanisms remains elusive. Our proteomic analysis identifies valosin-containing protein (VCP) as an mtHtt-binding protein on the mitochondria. Here we show that VCP is selectively translocated to the mitochondria, where it is bound to mtHtt in various HD models. Mitochondria-accumulated VCP elicits excessive mitophagy, causing neuronal cell death. Blocking mtHtt/VCP mitochondrial interaction with a peptide, HV-3, abolishes VCP translocation to the mitochondria, corrects excessive mitophagy and reduces cell death in HD mouse- and patient-derived cells and HD transgenic mouse brains. Treatment with HV-3 reduces behavioural and neuropathological phenotypes of HD in both fragment- and full-length mtHtt transgenic mice. Our findings demonstrate a causal role of mtHtt-induced VCP mitochondrial accumulation in HD pathogenesis and suggest that the peptide HV-3 might be a useful tool for developing new therapeutics to treat HD.

Immunoreactivity of valosin-containing protein in sporadic amyotrophic lateral sclerosis and in a case of its novel mutant

Background

Mutations in the valosin-containing protein (VCP) gene were first found to cause inclusion- body myopathy with early-onset Paget disease and frontotemporal dementia (IBMPFD). Mutations in the VCP gene were later reported to occur in familial amyotrophic lateral sclerosis (ALS). But the role of VCP in the neurodegenerative processes that occur in ALS remains unknown. The purpose of the present study was to elucidate the role of VCP in the neurodegeneration seen in sporadic and VCP mutant ALS.

Results

Immunohistochemistry demonstrated that the frequency of distinct VCP-positive nuclei of spinal motor neurons of patients with sporadic ALS (SALS) and the ALS with VCP novel mutation (ALS-VCP, M158V) was increased, compared with that of the control cases. No VCP-positive inclusion bodies were observed in SALS patients, a ALS-VCP patient or in control subjects. Neuropathologic examination of the ALS-VCP case showed loss of motor neurons, the presence of Bunina bodies, and degeneration of the corticospinal tracts. Bunina bodies detected in this case were confirmed to show immunohistochemical and ultrastructural features similar to those previously described. Furthermore, neuronal intracytoplasmic inclusions immunopositive for TAR DNA-binding protein 43 kDa (TDP-43), phosphorylated TDP-43, ubiquitin (Ub), p62, and optineurin were identified in the spinal and medullary motoneurons, but not in the neocortex. Gene analysis of this ALS-VCP patient confirmed the de novo mutation of M158V, which was not found in control cases; and bioinformatics using several in silico analyses showed possible damage to the structure of VCP. Immunocytochemical study of cultured cells showed increased cytoplasmic translocation of TDP-43 in cells transfected with several mutant VCP including our patient’s compared with wild-type VCP.

Conclusion

These findings support the idea that VCP is associated with the pathomechanism of SALS and familial ALS with a VCP mutation, presumably acting through a dominant-negative mechanism.

Electronic supplementary material

The online version of this article (doi:10.1186/s40478-014-0172-0) contains supplementary material, which is available to authorized users.

Deciphering genetic interactions between ALS genes using C. elegans

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder causing selective death of motor neurons in which it is speculated that 10% of cases have a familial history. In the past 20 years, many genes causative for ALS have been discovered, but the link between them and their roles in neurodegeneration remain unknown. The identification of genes associated with both ALS and frontotemporal dementia (FTD), along with the observation of patients affected by both diseases, have suggested that they are part of the same neurodegenerative spectrum. Investigating possible genetic interactions among ALS/FTD genes could help understand the role of these genes in neurodegeneration. To pursue this goal, our group has developed several ALS models to study potential genetic interactions. More recently, we characterized the deletion mutant alfa-1, the ortholog of C9ORF72, to evaluate the potential genetic interactions between C9ORF72/alfa-1 and other ALS genes. Here, we discuss the genetic interactions identified in our models and how some of these proteins may also be linked to other neurodegenerative disorders.

Worming forward: amyotrophic lateral sclerosis toxicity mechanisms and genetic interactions in Caenorhabditis elegans

Neurodegenerative diseases share pathogenic mechanisms at the cellular level including protein misfolding, excitotoxicity and altered RNA homeostasis among others. Recent advances have shown that the genetic causes underlying these pathologies overlap, hinting at the existence of a genetic network for neurodegeneration. This is perhaps best illustrated by the recent discoveries of causative mutations for amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD). Once thought to be distinct entities, it is now recognized that these diseases exist along a genetic spectrum. With this wealth of discoveries comes the need to develop new genetic models of ALS and FTD to investigate not only pathogenic mechanisms linked to causative mutations, but to uncover potential genetic interactions that may point to new therapeutic targets. Given the conservation of many disease genes across evolution, Caenorhabditis elegans is an ideal system to investigate genetic interactions amongst these genes. Here we review the use of C. elegans to model ALS and investigate a putative genetic network for ALS/FTD that may extend to other neurological disorders.