Hideomi Hamasaki

Loss of hnRNPA1 in ALS spinal cord motor neurons with TDP‐43‐positive inclusions

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by loss of motor neurons and appearance of skein‐like inclusions. The inclusions are composed of trans‐activation response (TAR) DNA‐binding protein 43 (TDP‐43), a member of the heterogeneous nuclear ribonucleoprotein (hnRNP) family. hnRNPA1 and hnRNPA2/B1 are hnRNPs that interact with the C‐terminus of TDP‐43. Using immunohistochemistry, we investigated the association between TDP‐43 and hnRNPA1 in ALS spinal motor neurons. We examined spinal cords of seven ALS cases and six muscular dystrophy cases (used as controls) for the presence of TDP‐43 and hnRNPA1 protein. In the control cases, hnRNPA1 immunoreactivity in motor neurons was intense in the nucleus and weak in the cytoplasm where it showed a fine granular appearance. In the ALS cases, hnRNPA1 immunoreactivity in motor neurons was reduced in the nuclei of neurons with skein‐like inclusions but was not detected in the skein‐like inclusions. The marked loss of hnRNPA1 in motor neurons with concomitant cytoplasmic aggregation of TDP‐43 may represent a severe disturbance of mRNA processing, suggesting a key role in progressive neuronal death in ALS.

Molecular pathophysiology of impaired glucose metabolism, mitochondrial dysfunction, and oxidative DNA damage in Alzheimer's disease brain

In normal brain, neurons in the cortex and hippocampus produce insulin, which modulates glucose metabolism and cognitive functions. It has been shown that insulin resistance impairs glucose metabolism and mitochondrial function, thus increasing production of reactive oxygen species. Recent progress in Alzheimers disease (AD) research revealed that insulin production and signaling are severely impaired in AD brain, thereby resulting in mitochondrial dysfunction and increased oxidative stress. Among possible oxidative DNA lesions, 8-oxoguanine (8-oxoG) is highly accumulated in the brain of AD patients. Previously we have shown that incorporating 8-oxoG in nuclear and mitochondrial DNA promotes MUTYH (adenine DNA glycosylase) dependent neurodegeneration. Moreover, cortical neurons prepared from MTH1 (8-oxo-dGTPase)/OGG1 (8-oxoG DNA glycosylase)-double deficient adult mouse brains is shown to exhibit significantly poor neuritogenesis in vitro with increased 8-oxoG accumulation in mitochondrial DNA in the absence of antioxidants. Therefore, 8-oxoG can be considered involved in the neurodegenerative process in AD brain. In mild cognitive impairment, mitochondrial dysfunction and oxidative damage may induce synaptic dysfunction due to energy failures in neurons thus resulting in impaired cognitive function. If such abnormality lasts long, it can lead to vicious cycles of oxidative damage, which may then trigger the neurodegenerative process seen in Alzheimer type dementia.

Trends in autopsy-verified dementia prevalence over 29 years of the Hisayama study

We investigated the trends in dementia over the past 29 years in the town of Hisayama, Japan using 1266 autopsy specimens. The Hisayama study is a prospective cohort study of lifestyle‐related diseases that was started in 1961. Clinical examination of dementia was started in 1985 with five detailed cross‐sectional assessments conducted in 1985, 1992, 1998, 2005 and 2012. To examine the trends in dementia, we divided the 1266 autopsy samples into five groups according to the year of death: I (1986–1991, 257 cases), II (1992–1997, 268 cases), III (1998–2004, 318 cases), IV (2005–2011, 296 cases) and V (2012–2014, 127 cases). The prevalence of all‐cause dementia significantly increased over time (28.4% in group I, 22.4% in group II, 32.1% in group III, 30.1% in group IV, 51.2% in group V; P for trend <0.001). A similar trend was observed for Alzheimers disease (AD) (15.2%, 11.9%, 17.3%, 20.6% and 33.1%, respectively; P for trend <0.001). A significant increasing trend was observed in both men and women. A rapid increase in senile dementia of the NFT type (SD‐NFT) in recent years was notable. Vascular dementia was the most common type of dementia in men prior to 2004; however, its prevalence decreased over time. Our study revealed that tauopathies, including AD and SD‐NFT, significantly increased in the aged Japanese population over the course of this study. The neuritic plaque pathology of AD was associated with metabolic disorders such as insulin resistance and abnormal lipid metabolism, whereas the risk factors for tau pathology remain unclear. Although aging is considered one of the important risk factors accelerating tau pathology, there could be other risk factors associated with lifestyle diseases.

Elevated expression of fatty acid synthase and nuclear localization of carnitine palmitoyltransferase 1C are common among human gliomas

Fatty acid synthase (FASN) and carnitine palmitoyltransferase 1C (CPT1C), a brain‐specific isoform of the CPT1 family, are upregulated in certain types of cancers, including gliomas. Acetyl‐CoA carboxylase (ACC) catalyzes the carboxylation of acetyl‐CoA to malonyl‐CoA, the rate‐limiting step in fatty acid synthesis, and its phosphorylated form inhibits lipid synthesis. We examined the expression and subcellular localization of these fatty acid metabolism‐related molecules in human gliomas. We performed immunostaining of two glioma cell lines (U373MG and U87MG) and 41 surgical specimens of diffuse gliomas with various histological grades (21 with the isocitrate dehydrogenase 1(IDH1) R132H mutation and 20 without the mutation). In the cultured glioma cells, CPT1C and phosphorylated ACC (p‐ACC) were mainly localized to the nuclei, whereas FASN localized to the cytoplasm. In the surgical specimens, most glioma tissues showed nuclear staining for CPT1C and p‐ACC, and cytoplasmic staining for FASN, regardless of the genetic status of IDH1 and the histological grade. Therefore, elevated cytoplasmic expression of FASN and nuclear localization of CPT1C are common among human diffuse gliomas, which may be regulated by the differential phosphorylation status of ACC in the cellular compartment.

Down-regulation of MET in hippocampal neurons of Alzheimer's disease brains.

We found that mRNA of MET, the receptor of hepatocyte growth factor (HGF), is significantly decreased in the hippocampus of Alzheimers disease (AD) patients. Therefore, we tried to determine the cellular component‐dependent changes of MET expressions. In this study, we examined cellular distribution of MET in the cerebral neocortices and hippocampi of 12 AD and 11 normal controls without brain diseases. In normal brains, MET immunoreactivity was observed in the neuronal perikarya and a subpopulation of astrocytes mainly in the subpial layer and white matter. In AD brains, we found marked decline of MET in hippocampal pyramidal neurons and granule cells of dentate gyrus. The decline was more obvious in the pyramidal neurons of the hippocampi than that in the neocortical neurons. In addition, we found strong MET immunostaining in reactive astrocytes, including those near senile plaques. Given the neurotrophic effects of the HGF/MET pathway, this decline may adversely affect neuronal survival in AD cases. Because it has been reported that HGF is also up‐regulated around senile plaques, β‐amyloid deposition might be associated with astrocytosis through the HGF signaling pathway.

Association of adipocyte enhancer-binding protein 1 with Alzheimer's disease pathology in human hippocampi

Adipocyte enhancer binding protein 1 (AEBP1) activates inflammatory responses via the NF‐κB pathway in macrophages and regulates adipogenesis in preadipocytes. Up‐regulation of AEBP1 in the hippocampi of patients with Alzheimers disease (AD) has been revealed by microarray analyses of autopsied brains from the Japanese general population (the Hisayama study). In this study, we compared the expression patterns of AEBP1 in normal and AD brains, including in the hippocampus, using immunohistochemistry. The subjects were 24 AD cases and 52 non‐AD cases. Brain specimens were immunostained with antibodies against AEBP1, tau protein, amyloid β protein, NF‐κB, GFAP and Iba‐1. In normal brains, AEBP1 immunoreactivity mainly localized to the perikarya of hippocampal pyramidal neurons, and its expression was elevated in the pyramidal neurons and some astrocytes in AD hippocampi. Although AEBP1 immunoreactivity was almost absent in neurons containing neurofibrillary tangles, AEBP1 was highly expressed in neurons with pretangles and in the tau‐immunopositive, dystrophic neurites of senile plaques. Nuclear localization of NF‐κB was also observed in certain AEBP1‐positive neurons in AD cases. Comparison of AD and non‐AD cases suggested a positive correlation between the expression level of AEBP1 and the degree of amyloid β pathology. These findings imply that AEBP1 protein has a role in the progression of AD pathology.

Recent Increases in Hippocampal Tau Pathology in the Aging Japanese Population: The Hisayama Study

BACKGROUND The Hisayama study is a prospective cohort study of lifestyle-related diseases that commenced in 1961. Through it, a significant increasing trend in the prevalence of Alzheimers disease has been observed over the past 18 years. OBJECTIVES We sought to investigate the increases in brain pathology related to Alzheimers disease using automated MATLAB morphometric analyses for quantifying tau pathology. METHODS We examined a series of autopsied cases from Hisayama residents obtained between 1998 and 2003 (group A: 203 cases), and between 2009 and 2014 (group B: 232 cases). We developed custom software in MATLAB to analyze abnormal tau deposits quantitatively. Specimens were immunostained with both anti-amyloid-β-protein and anti-phosphorylated tau antibodies. RESULTS Both the Consortium to Establish a Registry for Alzheimers Disease (CERAD) criteria for senile plaques and Braak stage for NFT were higher in group B. Morphometric analyses of the hippocampi also revealed a trend toward increased tau pathology in both men and women over 80 years of age in group B. The increases were also significant when the subjects were examined independently according to high or low CERAD scores and in all levels of AD neuropathologic change according to the National Institute on Aging-Alzheimers Association guidelines (2012). CONCLUSION We revealed a recent trend of increased tauopathy in the older people, which is partly independent of amyloid-β pathology.

DCTN1 F52L mutation case of Perry syndrome with progressive supranuclear palsy-like tauopathy

INTRODUCTION Perry syndrome is a rapidly progressive, autosomal dominant parkinsonism characterized by central hypoventilation, depression and severe weight loss. To date, eight DCTN1 mutations have been identified associated with Perry syndrome. A novel F52L DCTN1 mutation case of Perry syndrome is characterized by late-onset parkinsonism and frontotemporal atrophy. METHODS A Japanese woman suffered from slowly progressing parkinsonism since age 48. At age 59, she developed central hypoventilation, and required breathing assistance. Gene analysis identified a p.F52L mutation in DCTN1 and she was diagnosed with Perry syndrome. She died of aspiration pneumonia at age 74. RESULTS Postmortem examination revealed severe neuronal loss in the substantia nigra and the putamen. Immunohistochemistry for DCTN1 revealed many abnormal aggregates, mainly in neurons in the brainstem and basal ganglia. Additionally, numerous abnormal phosphorylated tau deposits including neurofibrillary tangles, tuft-shaped astrocytes and coiled bodies were observed mainly in the basal ganglia, brainstem and cerebellum. These correspond with the neuropathologic criteria for progressive supranuclear palsy. Colocalization of DCTN1 and tau were occasionally seen. Colocalization of phosphorylated α-synuclein and DCTN1 were also observed in Lewy body-like structures in oculomotor nuclei. Phosphorylated TARDBP-positive neuronal cytoplasmic inclusions were few. CONCLUSION In conjunction with long disease duration and aging, our findings suggest that the F52L DCTN1 mutation may evoke severe tauopathy and moderate α-synucleinopathy.

Expression of CRYM in different rat organs during development and its decreased expression in degenerating pyramidal tracts in amyotrophic lateral sclerosis

The protein μ‐crystallin (CRYM) is a novel component of the marsupial lens that has two functions: it is a key regulator of thyroid hormone transportation and a reductase of sulfur‐containing cyclic ketimines. In this study, we examined changes of the expression pattern of CRYM in different rat organs during development using immunohistochemistry and immunoblotting. As CRYM is reportedly expressed in the corticospinal tract, we also investigated CRYM expression in human cases of amyotrophic lateral sclerosis (ALS) using immunohistochemistry. In the rat brain, CRYM was expressed in the cerebral cortex, basal ganglia, hippocampus and corticospinal tract in the early postnatal period. As postnatal development progressed, CRYM expression was restricted to large pyramidal neurons in layers V and VI of the cerebral cortex and pyramidal cells in the deep layer of CA1 in the hippocampus. Even within the same regions, CRYM‐positive and negative neurons were distributed in a mosaic pattern. In the kidney, CRYM was expressed in epithelial cells of the proximal tubule and mesenchymal cells of the medulla in the early postnatal period; however, CRYM expression in the medulla was lost as mesenchymal cell numbers decreased with the rapid growth of the medulla. In human ALS brains, we observed marked loss of CRYM in the corticospinal tract, especially distally. Our results suggest that CRYM may play roles in development of cortical and hippocampal pyramidal cells in the early postnatal period, and in the later period, performs cell‐specific functions in selected neuronal populations. In the kidney, CRYM may play roles in maturation of renal function. The expression patterns of CRYM may reflect significance of its interactions with T3 or ketimines in these cells and organs. The results also indicate that CRYM may be used as a marker of axonal degeneration in the corticospinal tract.

Dynactin is involved in Lewy body pathology: Dynactin in Lewy bodies

Dynactin forms a protein complex with dynein that retrogradely transports cargo along microtubules. Dysfunction of this dynein‐dynactin complex causes several neurodegenerative diseases such as Perry syndrome, motor neuron diseases and progressive supranuclear palsy. Recently, we reported colocalization of phosphorylated α‐synuclein (p‐SNCA) and the largest subunit of dynactin (DCTN1) in Lewy body (LB)‐like structures in Perry syndrome. Previous reports have not focused on the relationship between dynactin and synucleinopathies. Thus, we examined autopsied human brains from patients with Parkinsons disease, dementia with LBs, and multiple system atrophy using immunohistochemistry for p‐SNCA, DCTN1, dynactin 2 (DCTN2, dynamitin) and dynein cytoplasmic 1 intermediate chain 1 (DYNC1I1). We also examined microtubule affinity‐regulating kinases (MARKs), which phosphorylate microtubule‐associated proteins and trigger microtubule disruption. Both brainstem‐type and cortical LBs were immunopositive for DCTN1, DCTN2, DYNC1I1 and p‐MARK and their staining often overlapped with p‐SNCA. Lewy neurites were also immunopositive for DCTN1, DCTN2 and DYNC1I1. However, p‐SNCA‐positive inclusions of multiple system atrophy, which included both glial and neuronal cytoplasmic inclusions, were immunonegative for DCTN1, DCTN2, DYNC1I1 and p‐MARK. Thus, immunohistochemistry for dynein‐dynactin complex molecules, especially DCTN1, can clearly distinguish LBs from neuronal cytoplasmic inclusions. Our results suggest that dynactin is closely associated with LB pathology.