Autopsied case with MERRF/MELAS overlap syndrome accompanied by stroke-like episodes localized to the precentral gyrus.

We present an autopsied case with A8344G-mutated myoclonus epilepsy with ragged red fibers (MERRF)/mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) overlap syndrome accompanied by stroke-like episodes localized to the precentral gyrus. A 16-year-old Japanese woman suddenly experienced repetitive consciousness disturbances with increased serum lactate and creatine kinase levels. Magnetic resonance imaging showed abnormal intensity of bilateral precentral gyrus. She was clinically diagnosed as having a mitochondrial disorder and the A8344G mutation was detected in mitochondrial DNA. At 17 years of age, she died from congestive heart failure secondary to a third episode of lactic acidosis. Neuropatho-logically, multifocal laminar necrosis, which is responsible for stroke-like episodes in MELAS, was seen in the frontal cortex including the precentral gyrus, but there was no neuronal loss and gliosis in the basal ganglia, cerebellum, and brainstem, which were compatible with MERRF. Hypertrophy of the vascular smooth muscle and choroidal epithelium were seen, and were strongly visualized by an anti-mitochondrial antibody. Skeletal muscles showed uneven muscular diameters, increased central nuclei, and ragged red fibers (RRFs). Decreased cytochrome c oxidase (COX) activity and strongly succinate dehydrogenase (SDH)-reactive blood vessels were also noted. Stroke-like episodes in MERRF/MELAS overlap syndrome are thought to be rare in the frontal cortex including the precentral gyrus. Only two cases of MERRF/MELAS overlap syndrome with A8344G mutation, including this case, have shown stroke-like episodes in the frontal lobes. Other than the A8344G mutation and frontal lobe involvement, they had a high degree of similarity in terms of presence of RRFs, gastrointestinal dysfunction, and lack of typical MERRF neuropathology. In conclusion, this is an important case describing the clinical spectrum associated with A8344G-mutated MERRF/MELAS overlap syndrome.

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.

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.

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.

[A case of Fisher syndrome presented by rapidly progressing bilateral palatoplegia after cytomegalovirus infection].

A 35-year-old male developed sensory abnormality of peripheral limbs and oral cavity after prior infection with diarrhea and cold symptoms. Hyperrhinolalia, nasopharyngeal reflux, double vision, and wobbling in walking rapidly progressed. Neurological examination revealed palatoplegia, omnidirectional ophthalmoplegia, hyperreflexia, sensory disturbance of extremities, and truncal and limb ataxia due to decreased deep sensation. A peripheral nerve conduction study found a slight decrease in sensory nerve action potential of the median nerve and a decrease in F wave frequency of the median nerve. Serum IgM-CMV antibody was positive on admission. After IVIg therapy, palatoplegia and ataxia markedly improved. In this case, GalNAc-GD1a and GM2 antibodies, which are often detected after CMV infection, were positive in addition to the GT1a and GQ1b antibodies, and it was assumed that these findings were associated with the palatoplegia, which is included in cranial nerve palsy. Pathophysiologically, the present case is considered to be an overlap with acute oropharyngeal palsy (AOP), which is a rare subtype of Guillain-Barre syndrome, and Fisher syndrome (FS). The clinical aspects of the present case suggest a continuous spectrum between AOP and FS.

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.

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) vector­mediated 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.