Hisatomo Kowa

CLAC: a novel Alzheimer amyloid plaque component derived from a transmembrane precursor, CLAC‐P/collagen type XXV

We raised monoclonal antibodies against senile plaque (SP) amyloid and obtained a clone 9D2, which labeled amyloid fibrils in SPs and reacted with ∼50/100 kDa polypeptides in Alzheimers disease (AD) brains. We purified the 9D2 antigens and cloned a cDNA encoding its precursor, which was a novel type II transmembrane protein specifically expressed in neurons. This precursor harbored three collagen‐like Gly–X–Y repeat motifs and was partially homologous to collagen type XIII. Thus, we named the 9D2 antigen as CLAC (collagen‐like Alzheimer amyloid plaque component), and its precursor as CLAC‐P/collagen type XXV. The extracellular domain of CLAC‐P/collagen type XXV was secreted by furin convertase, and the N‐terminus of CLAC deposited in AD brains was pyroglutamate modified. Both secreted and membrane‐tethered forms of CLAC‐P/collagen type XXV specifically bound to fibrillized Aβ, implicating these proteins in β‐amyloidogenesis and neuronal degeneration in AD.

Familial Parkinson Mutant α-Synuclein Causes Dopamine Neuron Dysfunction in Transgenic Caenorhabditis elegans

Mutations in α-synuclein gene cause familial form of Parkinson disease, and deposition of wild-type α-synuclein as Lewy bodies occurs as a hallmark lesion of sporadic Parkinson disease and dementia with Lewy bodies, implicating α-synuclein in the pathogenesis of Parkinson disease and related neurodegenerative diseases. Dopamine neurons in substantia nigra are the major site of neurodegeneration associated with α-synuclein deposition in Parkinson disease. Here we establish transgenic Caenorhabditis elegans (TG worms) that overexpresses wild-type or familial Parkinson mutant human α-synuclein in dopamine neurons. The TG worms exhibit accumulation of α-synuclein in the cell bodies and neurites of dopamine neurons, and EGFP labeling of dendrites is often diminished in TG worms expressing familial Parkinson disease-linked A30P or A53T mutant α-synuclein, without overt loss of neuronal cell bodies. Notably, TG worms expressing A30P or A53T mutant α-synuclein show failure in modulation of locomotory rate in response to food, which has been attributed to the function of dopamine neurons. This behavioral abnormality was accompanied by a reduction in neuronal dopamine content and was treatable by administration of dopamine. These phenotypes were not seen upon expression of β-synuclein. The present TG worms exhibit dopamine neuron-specific dysfunction caused by accumulation of α-synuclein, which would be relevant to the genetic and compound screenings aiming at the elucidation of pathological cascade and therapeutic strategies for Parkinson disease.

Amyloid β protein deposition in patients with frontotemporal lobar degeneration: relationship to age and apolipoprotein E genotype

Amyloid beta protein (Abeta) deposition was investigated in the frontal cortex of 54 autopsy cases of frontotemporal lobar degeneration (FTLD) using methenamine silver staining, and immunohistochemistry employing the monoclonal end-specific antibodies BC05 and BA27 to visualize deposits containing Abeta(42(43)) and Abeta(40), respectively. Abeta was detected in 14 (26%) patients, nearly always in the form of diffuse Abeta(42(43)) containing plaques though some cored, neuritic plaques with trace amounts of Abeta(40) were occasionally seen. The 14 patients showing Abeta deposits were significantly older at onset of illness than those 40 patients without Abeta. It was only possible to genotype 46/54 cases, 16 of whom bore at least one copy of the Apolipoprotein E (APOE) epsilon4 allele, giving an allele frequency of 20%. Possession of APOE epsilon4 allele was significantly associated with deposition of Abeta such that 10/16 epsilon4 allele bearers had Abeta deposits. Eight of these ten patients showed only mild to moderate amounts of Abeta, but in two patients, one homozygous and one heterozygous for epsilon4 allele, there was extensive neuritic plaque and neurofibrillary tangle formation. In contrast, only few non-epsilon4 allele bearers (4/30) showed minor Abeta deposits. When stratifying for APOE epsilon4 allele, both bearers and non-bearers of epsilon4 allele with Abeta deposits had a significantly later age at onset than their respective groups without Abeta deposits. We conclude that the likelihood of Abeta deposition, as a secondary and coincidental feature unrelated to the primary pathological process, within the brains of individuals with FTLD will be high if patients have a sufficiently late onset of illness or happen to be a bearer of the APOE epsilon4 allele. Indeed 9/14 patients with Abeta deposits studied here had an onset of illness after 55 years of age and bore APOE epsilon4 allele.

Somatosensory evoked potential recovery in myotonic dystrophy

OBJECTIVE To evaluate recovery functions of the sensory cortex using somatosensory evoked potentials (SEPs) elicited by paired stimuli of the median nerve in patients with myotonic dystrophy (MD). SUBJECTS/METHODS Twelve MD patients were enrolled in the present investigation. Five patients with facioscapulohumeral muscular dystrophy (FSH) and 12 healthy volunteers were studied as control groups. SEP was recorded from the hand sensory area contralateral to the median nerve stimulated at the wrist. Single pulse or paired-pulse stimuli at various interstimulus intervals (ISIs) (10, 20, 40, 60, 80, 100, 150, 200 and 300 ms) were given. Recovery functions of N9, N20onset-N20peak, N20-P25 and P25-N33 components were studied. RESULTS Conventional SEPs to a single stimulus were normal in the latency and amplitude in all the patients. Recovery functions of both N9 and N20o-N20p components were normal in the patients. In contrast, in MD patients, disinhibited or hyperexcitable recovery pattern was observed in recovery curves of the N20-P25 or P25-N33 components, whereas those were normal in FSH patients. CONCLUSIONS Disinhibited cortical excitability (or hyperexcitability) is present in the sensory cortex in patients with myotonic dystrophy. This may reflect cortical pathology or functional alteration of the sensory cortex in MD.

Severe Hypokinesis Caused by Paraneoplastic Anti-Ma2 Encephalitis Associated with Bilateral Intratubular Germ-Cell Neoplasm of the Testes

We report a 40‐year‐old man with severe hypokinesis as paraneoplastic manifestation of a microscopic “carcinoma in situ” of the testis. The young age of the patient, along with progressive neurologic deterioration, detection of anti‐Ma2 antibodies, and ultrasound findings of bilateral microcalcifications, led to bilateral orchiectomy, revealing the tumor in both testes. After orchiectomy, neurological symptoms stabilized, but the patient eventually died of systemic complications caused by his severe neurological deficits. Anti‐Ma2 paraneoplastic encephalitis should be considered in patients with severe hypokinesis, and intensive investigation and aggressive approach to treatment is encouraged to prevent progression of the neurological deficits.

Mostly Separate Distributions of CLAC- versus Aβ40- or Thioflavin S-Reactivities in Senile Plaques Reveal Two Distinct Subpopulations of β-Amyloid Deposits

Collagenous Alzheimer amyloid plaque component (CLAC) is a unique non-Abeta amyloid component of senile plaques (SP) derived from a transmembrane collagen termed CLAC-precursor. Here we characterize the chronological and spatial relationship of CLAC with other features of SP amyloid in the brains of patients with Alzheimers disease (AD), Down syndrome (DS), and of PSAPP transgenic mice. In AD and DS cerebral cortex, CLAC invariably colocalized with Abeta42 but often lacked Abeta40- or thioflavin S (thioS)-reactivities. Immunoelectron microscopy of CLAC-positive SP showed labeling of fibrils that are more loosely dispersed compared to typical amyloid fibrils in CLAC-negative SP. In DS cerebral cortex, diffuse plaques in young patients were negative for CLAC, whereas a subset of SP became CLAC-positive in patients aged 35 to 50 years, before the appearance of Abeta40. In DS cases over 50 years of age, Abeta40-positive SP dramatically increased, whereas CLAC burden remained at a constant level. In PSAPP transgenic mice, CLAC was positive in the diffuse Abeta deposits surrounding huge-cored plaques. Thus, CLAC and Abeta40 or thioS exhibit mostly separate distribution patterns in SP, suggesting that CLAC is a relatively early component of SP in human brains that may have inhibitory effects against the maturation of SP into beta-sheet-rich amyloid deposits.

FAT10 protein binds to polyglutamine proteins and modulates their solubility

Expansion of polyglutamine (pQ) chain by expanded CAG repeat causes dominantly inherited neurodegeneration such as Huntington disease, dentatorubral-pallidoluysian atrophy (DRPLA), and numbers of other spinocerebellar ataxias. Expanded pQ disrupts the stability of the pQ-harboring protein and increases its susceptibility to aggregation. Aggregated pQ protein is recognized by the ubiquitin proteasome system, and the enzyme ubiquitin ligase covalently attaches ubiquitin, which serves as a degradation signal by the proteasome. However, accumulation of the aggregated proteins in the diseased brain suggests insufficient degradation machinery. Ubiquitin has several functionally related proteins that are similarly attached to target proteins through its C terminus glycine residue. They are called ubiquitin-like molecules, and some of them are similarly related to the protein degradation pathway. One of the ubiquitin-like molecules, FAT10, is known to accelerate protein degradation through a ubiquitin-independent manner, but its role in pQ aggregate degradation is completely unknown. Thus we investigated its role in a Huntington disease cellular model and found that FAT10 molecules were covalently attached to huntingtin through their C terminus glycine. FAT10 binds preferably to huntingtin with a short pQ chain and completely aggregated huntingtin was FAT10-negative. In addition, ataxin-1,3 and DRPLA proteins were both positive for FAT10, and aggregation enhancement was observed upon FAT10 knockdown. These findings were similar to those for huntingtin. Our new finding will provide a new role for FAT10 in the pathogenesis of polyglutamine diseases.

Aceruloplasminemia in a Japanese woman with a novel mutation of CP gene: Clinical presentations and analysis of genetic and molecular pathogenesis

We report a Japanese woman diagnosed as aceruloplasminemia showing characteristic symptoms. Mutational analysis of CP gene revealed a novel homozygous mutation in exon 18, resulting in prematurely truncated W1017X protein. In vitro study showed that W1017X mutant ceruloplasmin was deficient in endoplasmic reticulum to Golgi trafficking and was not secreted to medium. It has been reported that the presence of both the G (FLI/LI) GP domain and the 881th cysteine residue was sufficient for secretion. Thus, our report on this novel mutant indicates the previously unreported importance of carboxy-terminus residues in the secretion pathway.

Presenilin-1 C410Y Alzheimer Disease Plaques Contain Synaptic Proteins

Presenilin-1 (PS-1) mutations are associated with familial Alzheimers disease (AD). Although beta-amyloid (Aβ) plaques in brain tissue are characteristic of AD patients, space occupying “cotton-wool” plaques (CWPs) lacking dense Aβ cores have also been described in patients with mutations in exon 9 of the PS-1 gene. The composition of CWPs has not been fully described. To better elucidate the composition of these space-occupying plaques, we used immunohistochemistry with antibodies to the synaptic proteins synapsin-1 and synaptophysin, as well as antibodies to tau, Aβ-42, Aβ-40, ubiquitin, neurofilament, and glial fibrillary acidic protein. Confocal laser scanning microscopy (CLSM) was utilized to further characterize these plaques. CWPs showed increased synapsin-1 and synaptophysin immunoreactivity relative to the background gray matter. Synaptic protein-containing CWPs occurred in all affected MTL regions, including the granule cell layer of the dentate gyrus, where synaptic terminals are usually sparse. These data suggest that in C410Y PS-1 AD patients, CWPs may constitute a major component of synaptic terminal-specific proteins, and that the C410Y PS-1 mutation may influence either synaptic structure or synaptic protein expression.

58. Interhemispheric inhibition in Alzheimer disease

lished. Our study aimed to investigate the relationships between pain and the stimulus duration when stimulus intensity is just sufficient to obtain the supramaximal stimulation. Fourteen normal subjects were enrolled for this evaluation. Tibial nerve was stimulated at the ankle with two out of three durations of 0.05, 0.2, and 1.0 ms. Six such combinations were tested in a random order, and subjects were asked to report which duration was more painful at each trial. Following two stimulus patterns were examined: pattern 1 was single supramaximal stimulation, and pattern 2 was a train of five maximal stimulations with 1 Hz, respectively. The stimulus duration with 0.2 ms caused minimum pain for both patterns, followed by 0.05 and 1.0 ms. This result indicate shorter duration is not always less painful. Furthermore, if we use 0.05 ms duration, the intensity necessary for supramaximal stimulation may easily exceed 100 mA for a pathological nerve with increased threshold. It is concluded that 0.2 ms duration, widely employed in Japan, is well appropriate.