Yu Miyazaki

Viral delivery of miR-196a ameliorates the SBMA phenotype via the silencing of CELF2

Spinal and bulbar muscular atrophy (SBMA) is an inherited neurodegenerative disorder caused by the expansion of the polyglutamine (polyQ) tract of the androgen receptor (AR-polyQ). Characteristics of SBMA include proximal muscular atrophy, weakness, contraction fasciculation and bulbar involvement. MicroRNAs (miRNAs) are a diverse class of highly conserved small RNA molecules that function as crucial regulators of gene expression in animals and plants. Recent functional studies have shown the potent activity of specific miRNAs as disease modifiers both in vitro and in vivo. Thus, potential therapeutic approaches that target the miRNA processing pathway have recently attracted attention. Here we describe a novel therapeutic approach using the adeno-associated virus (AAV) vector–mediated delivery of a specific miRNA for SBMA. We found that miR-196a enhanced the decay of the AR mRNA by silencing CUGBP, Elav-like family member 2 (CELF2). CELF2 directly acted on AR mRNA and enhanced the stability of AR mRNA. Furthermore, we found that the early intervention of miR-196a delivered by an AAV vector ameliorated the SBMA phenotypes in a mouse model. Our results establish the proof of principle that disease-specific miRNA delivery could be useful in neurodegenerative diseases.

p62/SQSTM1 Differentially Removes the Toxic Mutant Androgen Receptor via Autophagy and Inclusion Formation in a Spinal and Bulbar Muscular Atrophy Mouse Model

Polyglutamine (polyQ) diseases are inherited neurodegenerative disorders that are caused by the expansion of trinucleotide CAG repeats in the causative genes. Spinal and bulbar muscular atrophy (SBMA) is an inherited motor neuron disease that is caused by the expansion of a polyQ tract within the androgen receptor (AR). p62 is a ubiquitin- and light-chain 3-binding protein that is known to regulate the degradation of targeted proteins via autophagy and inclusion formation. In this study, we examined the effects of p62 depletion and overexpression on cultured cells and in a transgenic mouse model that overexpressed the mutant AR. Here, we demonstrate that depletion of p62 significantly exacerbated motor phenotypes and the neuropathological outcome, whereas overexpression of p62 protected against mutant AR toxicity in SBMA mice. Depletion of p62 significantly increased the levels of monomeric mutant AR and mutant AR protein complexes in an SBMA mouse model via the impairment of autophagic degradation. In addition, p62 overexpression improved SBMA mouse phenotypes by inducing cytoprotective inclusion formation. Our results demonstrate that p62 provides two different therapeutic targets in SBMA pathogenesis: (1) autophagy-dependent degradation and (2) benevolent inclusion formation of the mutant AR.

Heat shock factor-1 influences pathological lesion distribution of polyglutamine-induced neurodegeneration

A crucial feature of adult-onset neurodegenerative diseases is accumulation of abnormal protein in specific brain regions, although the mechanism underlying this pathological selectivity remains unclear. Heat shock factor-1 is a transcriptional regulator of heat shock proteins, molecular chaperones that abrogate neurodegeneration by refolding and solubilizing pathogenic proteins. Here we show that heat shock factor-1 expression levels are associated with the accumulation of pathogenic androgen receptor in spinal and bulbar muscular atrophy, a polyglutamine-induced neurodegenerative disease. In heterozygous heat shock factor-1-knockout spinal and bulbar muscular atrophy mice, abnormal androgen receptor accumulates in the cerebral visual cortex, liver and pituitary, which are not affected in their genetically unmodified counterparts. The depletion of heat shock factor-1 also expands the distribution of pathogenic androgen receptor accumulation in other neuronal regions. Furthermore, lentiviral-mediated delivery of heat shock factor-1 into the brain of spinal and bulbar muscular atrophy mice topically suppresses the pathogenic androgen receptor accumulation and neuronal atrophy. These results suggest that heat shock factor-1 influences the pathological lesion selectivity in spinal and bulbar muscular atrophy.

Naratriptan mitigates CGRP1-associated motor neuron degeneration caused by an expanded polyglutamine repeat tract

Spinal and bulbar muscular atrophy (SBMA) is a motor neuron disease caused by the expansion of the CAG triplet repeat within the androgen receptor (AR) gene. Here, we demonstrated that pathogenic AR upregulates the gene encoding calcitonin gene-related peptide α (CGRP1). In neuronal cells, overexpression of CGRP1 induced cellular damage via the activation of the c-Jun N-terminal kinase (JNK) pathway, whereas pharmacological suppression of CGRP1 or JNK attenuated the neurotoxic effects of pathogenic AR. The depletion of CGRP1 inactivated JNK and suppressed neurodegeneration in a mouse model of SBMA. Naratriptan, a serotonin 1B/1D (5-hydroxytryptamine 1B/1D, or 5-HT1B/1D) receptor agonist, decreased CGRP1 expression via the induction of dual-specificity protein phosphatase 1 (DUSP1), attenuated JNK activity and mitigated pathogenic AR-mediated neuronal damage in cellular and mouse SBMA models. These observations suggest that pharmacological activation of the 5-HT1B/1D receptor may be used therapeutically to treat SBMA and other polyglutamine-related neurodegenerative diseases.

Paeoniflorin eliminates a mutant AR via NF-YA-dependent proteolysis in spinal and bulbar muscular atrophy

The accumulation of abnormal proteins is a common characteristic of neurodegenerative diseases. This accumulation reflects a severe disturbance of cellular homeostasis in pathogenic protein clearance. Here, we demonstrated that the activation of the two major proteolytic machineries, the molecular chaperone-ubiquitin proteasome system (UPS) and the autophagy system, were simultaneously enhanced by paeoniflorin (PF), a major component of Paeonia plants, and exerted therapeutic effects in models of spinal and bulbar muscular atrophy (SBMA). PF significantly increased the expression of nuclear factor-YA (NF-YA), which strongly upregulated the molecules involved in the proteolytic machinery [molecular chaperones, carboxyl terminus of Hsc70-interacting protein and transcription factor EB], which thus mitigated the behavioral and pathological impairments in an SBMA mouse model through the upregulation of pathogenic androgen receptor protein clearance in motor neurons and muscles. These findings demonstrated that PF is able to enhance both the UPS and autophagy systems by upregulating the expression of NF-YA, which promotes therapeutic effects in an SBMA model.

An miRNA-mediated therapy for SCA6 blocks IRES-driven translation of the CACNA1A second cistron

Selective translational blockade of the CACNA1A second cistron using miRNAs may have potential for treating spinocerebellar ataxia type 6. Blunting the sharp end of the spear Selectively turning off disease genes without disrupting other processes has been a growing goal of genetic research. In a new study, Miyazaki et al. work with a gene that expresses two proteins, a calcium channel, necessary for life, and a regulatory protein, α1ACT, which when mutated causes a form of ataxia called SCA6. These investigators figured out how to block expression of the disease protein without affecting the calcium channel using a small sequence of RNA called miRNA. They then used a viral vector to deliver this miRNA to mice engineered to develop a severe form of SCA6 and successfully prevented the disease. Spinocerebellar ataxia type 6 (SCA6) is a dominantly inherited neurodegenerative disease characterized by slowly progressive ataxia and Purkinje cell degeneration. SCA6 is caused by a polyglutamine repeat expansion within a second CACNA1A gene product, α1ACT. α1ACT expression is under the control of an internal ribosomal entry site (IRES) present within the CACNA1A coding region. Whereas SCA6 allele knock-in mice show indistinguishable phenotypes from wild-type littermates, expression of SCA6-associated α1ACT (α1ACTSCA6) driven by a Purkinje cell–specific promoter in mice produces slowly progressive ataxia and cerebellar atrophy. We developed an early-onset SCA6 mouse model using an adeno-associated virus (AAV)–based gene delivery system to ectopically express CACNA1A IRES–driven α1ACTSCA6 to test the potential of CACNA1A IRES–targeting therapies. Mice expressing AAV9-mediated CACNA1A IRES–driven α1ACTSCA6 exhibited early-onset ataxia, motor deficits, and Purkinje cell degeneration. We identified miR-3191-5p as a microRNA (miRNA) that targeted CACNA1A IRES and preferentially inhibited the CACNA1A IRES–driven translation of α1ACT in an Argonaute 4 (Ago4)–dependent manner. We found that eukaryotic initiation factors (eIFs), eIF4AII and eIF4GII, interacted with the CACNA1A IRES to enhance α1ACT translation. Ago4-bound miR-3191-5p blocked the interaction of eIF4AII and eIF4GII with the CACNA1A IRES, attenuating IRES-driven α1ACT translation. Furthermore, AAV9-mediated delivery of miR-3191-5p protected mice from the ataxia, motor deficits, and Purkinje cell degeneration caused by CACNA1A IRES–driven α1ACTSCA6. We have established proof of principle that viral delivery of an miRNA can rescue a disease phenotype through modulation of cellular IRES activity in a mouse model.

VZV vasculopathy associated with myelo-radiculoganglio-meningo-encephalitis: An autopsy case of an immunocompetent 66-year-old male

Encephalitis is the most severe manifestation of central nervous system (CNS) infection by Varicella-Zoster-Virus (VZV). VZV associated encephalitis is now recognized to be a vasculopathy that affects large or small cerebral arteries. This report describes an autopsy case of an immunocompetent 66-year-old male who developed a progressive small vessel vasculopathy and clinically presented with a zosteriform rash and myelo-radiculoganglio-meningo-encephalitis followed by subarachnoid bleeding. This is an extremely rare manifestation of VZV vasculopathy associated with widespread CNS damage, and what is more, the spinal lesions were different from those of the cerebrum, brainstem and cerebellum, where the former were predominantly demyelinative changes and the latter were ischemic. To the best of our knowledge, few cases have been described pathologically in an immunocompetent individual. Further studies are needed to investigate the pathogenesis and treatment of VZV vasculopathy.

Pioglitazone suppresses neuronal and muscular degeneration caused by polyglutamine-expanded androgen receptors

Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by the expansion of a CAG repeat in the androgen receptor (AR) gene. Mutant AR has been postulated to alter the expression of genes important for mitochondrial function and induce mitochondrial dysfunction. Here, we show that the expression levels of peroxisome proliferator-activated receptor-γ (PPARγ), a key regulator of mitochondrial biogenesis, were decreased in mouse and cellular models of SBMA. Treatment with pioglitazone (PG), an activator of PPARγ, improved the viability of the cellular model of SBMA. The oral administration of PG also improved the behavioral and histopathological phenotypes of the transgenic mice. Furthermore, immunohistochemical and biochemical analyses demonstrated that the administration of PG suppressed oxidative stress, nuclear factor-κB (NFκB) signal activation and inflammation both in the spinal cords and skeletal muscles of the SBMA mice. These findings suggest that PG is a promising candidate for the treatment of SBMA.

Spinal cord stimulation markedly ameliorated refractory neuropathic pain in transthyretin Val30Met familial amyloid polyneuropathy

Although spinal cord stimulation has been reported to be effective for controlling neuropathic pain in diabetic neuropathy, it has rarely been investigated in other peripheral neuropathies. We describe, for the first time, the efficacy of spinal cord stimulation for refractory neuropathic pain in a patient with transthyretin Val30Met associated familial amyloid polyneuropathy (FAP ATTR Val30Met). A 72-year-old man was diagnosed as having FAP ATTR Val30Met when he was 70 years old. He had been complained of burning pain in the distal portion of his bilateral lower limbs since he was 69 years old. Because conventional symptomatic therapies, including nonsteroidal anti-inflammatory drugs, antiepileptic drugs, and tricyclic antidepressants did not ameliorate pain, he underwent bilateral lumbar spinal cord electrical stimulation at high frequency and low voltage at the level of Th12 vertebral body and this was markedly effective. Our case expands the application of spinal cord stimulation, which should be considered as an alternative therapeutic approach for relief of neuropathic pain, which can be extremely distressful for patients and may lead to an impaired quality of life.

Genistein, a natural product derived from soybeans, ameliorates polyglutamine‐mediated motor neuron disease

Spinal and bulbar muscular atrophy (SBMA) is an inherited motor neuron disease caused by the expansion of a polyglutamine (polyQ) tract within the androgen receptor (AR) gene. The pathologic features of SBMA are motor neuron loss in the spinal cord and brainstem, and diffuse nuclear accumulation and nuclear inclusions of mutant AR in residual motor neurons and certain visceral organs. AR‐associated coregulator 70 (ARA70) was the first coregulator of AR to be identified, and it has been shown to interact with AR and increase its protein stability. Here, we report that genistein, an isoflavone found in soy, disrupts the interaction between AR and ARA70 and promotes the degradation of mutant AR in neuronal cells and transgenic mouse models of SBMA. We also demonstrate that dietary genistein ameliorates behavioral abnormalities, improves spinal cord and muscle pathology, and decreases the amounts of monomeric AR and high‐molecular‐weight mutant AR protein aggregates in SBMA transgenic mice. Thus, genistein treatment may be a potential therapeutic approach for alleviating the symptoms of SBMA by disrupting the interactions between AR and ARA70.