Shigeki Arawaka

Mutant SOD1 linked to familial amyotrophic lateral sclerosis, but not wild-type SOD1, induces ER stress in COS7 cells and transgenic mice

Mutations in a Cu, Zn-superoxide dismutase (SOD1) cause motor neuron death in human familial amyotrophic lateral sclerosis (FALS) and its mouse model, suggesting that mutant SOD1 has a toxic effect on motor neurons. However, the question of how the toxic function is gained has not been answered. Here, we report that the mutant SOD1s linked to FALS, but not wild-type SOD1, aggregated in association with the endoplasmic reticulum (ER) and induced ER stress in the cDNA-transfected COS7 cells. These cells showed an aberrant intracellular localization of mitochondria and microtubules, which might lead to a functional disturbance of the cells. Motor neurons of the spinal cord in transgenic mice with a FALS-linked mutant SOD1 also showed a marked increase of GRP78/BiP, an ER-resident chaperone, just before the onset of motor symptoms. These data suggest that ER stress is involved in the pathogenesis of FALS with an SOD1 mutation.

Microalbuminuria is a risk factor for cerebral small vessel disease in community-based elderly subjects

Microalbuminuria (MA) is known as a marker for generalized vascular dysfunction. It occurs most commonly in the setting of diabetes and hypertension; however, its association with cerebral small vessel disease (SVD) in community-based elderly remains to be clarified. In this cross-sectional analysis, we evaluated the association between MA and cerebral SVD in total 651 community-based elderly subjects. We assessed cardiovascular risk factors by interviews and physical examinations, including an evaluation of urinary albumin creatinine ratio (UACR). All subjects underwent brain magnetic resonance imaging (MRI) and carotid ultrasonography. As endothelial markers, the serum levels of thrombomodulin (TM) and a tissue-type plasminogen activator/ plasminogen activator inhibitor-1 complex were also studied. The mean TM and UACR were higher in subjects with lacunar infarcts or with moderate white matter hyperintensities (mWMH) on MRI than in those without them. Additionally, the prevalence of lacunar infarcts or mWMH was higher in the highest tertile of UACR level than in the lowest or middle tertile. Furthermore, in logistic regression analysis, the elevation of logarithmically transformed UACR (log UACR) was associated with the higher likelihood for total lacunar infarcts (odds ratio [OR], 1.85 per one log UACR increase), multiple lacunar infarcts (OR, 1.89 per one log UACR increase), and mWMH (OR, 2.15 per one log UACR increase). The present study revealed that levels of urinary albumin are associated with cerebral SVD, independently of traditional cerebrovascular risk factors, in community-based elderly.

Cerebral small vessel disease and chronic kidney disease (CKD): results of a cross-sectional study in community-based Japanese elderly.

Chronic kidney disease (CKD) is known as a risk factor for cardiovascular disease. In recent years, several experimental and epidemiological studies have suggested that CKD is associated with endothelial dysfunction; thereby, a CKD state may initiate both large and small vessel damage. The association between renal dysfunction and asymptomatic lacunar infarction was reported in a hospital-based study, whereas the relationship between cerebral small vessel disease (SVD)-related lesions and CKD could not be clarified in a community-based study. We performed a cross-sectional study to determine the relationship between silent cerebral SVD-related lesions and CKD in a total of 625 community-based Japanese elderly. In this study, subjects with lower estimated glomerular filtration rate levels tended to have more lacunar infarcts and higher grades of white matter lesions (WMLs). In addition, the mean grades of WMLs or the mean numbers of lacunar infarction in the subjects with albuminuria were greater than those in subjects without albuminuria. In the logistic regression analysis, the association between the presence of CKD and lacunar infarction or moderate WMLs (Fazekas grades 2 and 3) was statistically significant (odds ratio [OR]: 1.86 and 1.50, respectively). Furthermore, as we performed additional analysis, excluding the subjects with stage 2 hypertension (those with casual blood pressure >or=160/100 mm Hg) or diabetes, CKD remained to be an independent risk for cerebral SVD-related lesions. This is the first study showing the relationship between silent SVD-related brain lesions and the presence of CKD, independently of conventional cardiovascular risk factors, in community-based elderly.

Neuroprotective effect of oxidized galectin-1 in a transgenic mouse model of amyotrophic lateral sclerosis.

Abnormal accumulation of neurofilaments in motor neurons is a characteristic pathological finding in amyotrophic lateral sclerosis (ALS). Recently, we revealed that galectin-1, whose oxidized form has axonal regeneration-enhancing activity, accumulates in the neurofilamentous lesions in ALS. To investigate whether oxidized galectin-1 has a beneficial effect on ALS, oxidized recombinant human galectin-1 (rhGAL-1/ox) or physiological saline was injected into the left gastrocnemius muscle of the transgenic mice over-expressing a mutant copper/zinc superoxide dismutase (SOD1) with a substitution of histidine to arginine at position 46 (H46R SOD1). The H46R SOD1 transgenic mice, which represented a new animal model of familial ALS, were subsequently assessed for their disease onset, life span, duration of illness, and motor function. Furthermore, the number of remaining large anterior horn cells of spinal cords was also compared between the two groups. The results showed that administration of rhGAL-1/ox to the mice delayed the onset of their disease and prolonged the life of the mice and the duration of their illness. Motor function, as evaluated by a Rotarod performance, was improved in rhGAL-1/ox-treated mice. Significantly more anterior horn neurons of the lumbar and cervical cords were preserved in the mice injected with rhGAL-1/ox than in those injected with physiological saline. The study suggests that rhGAL-1/ox administration could be a new therapeutic strategy for ALS.

Cerebral small vessel disease and C-reactive protein: results of a cross-sectional study in community-based Japanese elderly.

BACKGROUND AND PURPOSE Inflammatory processes are involved in the pathogenesis of atherosclerosis. Inflammation has been known as a risk factor for coronary heart disease, whereas inflammation as a risk for cerebrovascular disease is less well established. Whether inflammatory processes, excluded from their involvement in large-vessel disease, are implicated in the pathogenesis of cerebral small vessel disease remains unclear. We assessed whether higher C-reactive protein (CRP) levels were associated with an increased number of lacunar infarcts or severity of white matter lesions. METHODS AND RESULTS In a community-based group of Japanese elderly (n=689), CRP concentrations were measured using a highly sensitive assay. All participants underwent magnetic resonance imaging (MRI), and cerebral small vessel disease-related lesions (lacunar infarcts and white matter hyperintensity) were subsequently evaluated. Furthermore, carotid atherosclerosis was also assessed with ultrasonography. As the grades of white matter hyperintensity and the numbers of lacunes were considered small vessel disease-related lesions, we evaluated the relationships between CRP levels and small vessel disease-related brain lesions. Interestingly, the median CRP concentration of our participants was remarkably lower, being approximately one third or one quarter of the value of Western populations. Subjects with higher CRP levels tended to have more small vessel disease-related lesions; however, these associations were not seen after adjustment for cardiovascular risk factors and carotid atherosclerosis. CONCLUSIONS The relationship between CRP levels and small vessel disease-related lesions was not apparent in the community-based Japanese elderly. The impact of inflammation in the pathogenesis of small vessel disease-related brain lesions seems to be weak among the Japanese elderly.

A polymorphism of the aldehyde dehydrogenase 2 gene is a risk factor for multiple lacunar infarcts in Japanese men: the Takahata Study

The objective of the present study was to examine the association between a polymorphism of the aldehyde dehydrogenase 2 (ALDH2) gene and lacunar infarcts of the brain. We conducted a population‐based, cross‐sectional study on residents from two age groups (61‐ and 72‐year olds). A total of 376 subjects participated in the study, which included brain magnetic resonance image and genetic analysis of the ALDH2 gene. Of the 61‐ and 72‐year‐old subjects, 46.4% and 64.3%, respectively, had one or more lacunar infarcts. The average number of infarcts also increased from 2.0 to 2.8 in men and from 2.3 to 3.5 in women. No significant association between the ALDH2 genotype and the presence of lacunar infarction (≥1) was found. However, in subjects with lacunar infarction, the genotype of ALDH2 *1/*1 was associated with a larger number of the lesion [‘single’ versus ‘multiple’ odds ratio (OR) 3.73, 95%CI: 1.43–9.74] in men. The OR was comparable even after adjusting for alcohol consumption, tobacco habits, age, hypertension, hypercholesterolemia, and diabetes mellitus (DM) (OR 3.88; 95% CI: 1.10–13.66). In women, there was no significant association between the ALDH2 genotypes and lacunar infarcts. The present study revealed that the ALDH2 *1/*1 genotype was significantly associated with the prevalence of multiple lacunar infarcts in Japanese men.

N-terminal region of α-synuclein is essential for the fatty acid-induced oligomerization of the molecules

Exposure of α‐synuclein (αS), a major component of Lewy bodies in Parkinsons disease, to polyunsaturated fatty acids (PUFAs) triggers the formation of soluble αS oligomers. Here, we demonstrate that PUFA binds recombinant αS protein through its N‐terminal region (residues 2–60). In HEK293 cells, αS mutants lacking the N‐terminal region failed to form oligomers in the presence of PUFA. The PUFA‐induced αS oligomerization was accelerated by C‐terminal truncation or Ser129 phosphorylation of αS; however, this effect was abolished by deletion of the N‐terminus. The results indicate that the N‐terminus of αS is essential for the PUFA‐induced αS oligomerization.

Contribution of endogenous G-protein-coupled receptor kinases to Ser129 phosphorylation of α-synuclein in HEK293 cells

The majority of alpha-synuclein (alphaS) deposited in Lewy bodies, the pathological hallmark of Parkinsons disease (PD), is phosphorylated at serine 129 (Ser129). Ser129 phosphorylation of alphaS has been demonstrated to enhance the alphaS toxicity to dopaminergic neurons in a Drosophila model of PD. Phosphorylation of alphaS at Ser129 seems to play a crucial role in the pathogenesis of PD. Here, we assessed the contribution of ubiquitously expressing members of the G-protein-coupled receptor kinase family (GRK2, GRK3, GRK5, and GRK6) to Ser129 phosphorylation of alphaS in HEK293 cells. To selectively reduce the endogenous expression of each member of the GRK family in cells, we used small interfering RNAs. Knockdown of GRK3 or GRK6 significantly decreased Ser129 phosphorylation of alphaS; however, knockdown of GRK2 or GRK5 did not decrease alphaS phosphorylation. The results indicate that endogenous GRK3 and GRK6, but not GRK2 or GRK5, contribute to Ser129 phosphorylation of alphaS in HEK293 cells.

Serine 129 phosphorylation of membrane-associated α-synuclein modulates dopamine transporter function in a G protein–coupled receptor kinase–dependent manner

GRK-mediated Ser-129 phosphorylation of membrane-associated α-synuclein enhances dopamine uptake without altering cell surface expression of dopamine transporter. The data suggest a role of Ser-129–phosphorylated α-synuclein in modulating intracellular dopamine levels and damaging dopaminergic neurons in Parkinson disease.

Segmental copy-number gain within the region of isopentenyl diphosphate isomerase genes in sporadic amyotrophic lateral sclerosis

AIMS Sporadic amyotrophic lateral sclerosis (SALS) seems to be a multifactorial disease, the pathogenesis of which may involve both genetic and environmental factors. The present study aims at identifying a possible genetic change that confers risk for SALS. METHODS We performed whole-genome screening of a copy-number variation (CNV) using a CNV beadchip, followed by real-time quantitative polymerase chain reaction (qPCR) and region-targeted high-density oligonucleotide tiling microarray. RESULTS Within the 40-kb region on 10p15.3 subtelomere, which harbours two genes encoding isopentenyl diphosphate isomerase 1 (IDI1) and IDI2, we found a segmental copy-number gain in a large proportion of SALS patients. qPCR analysis demonstrated the copy-number gain in 46 out of 83 SALS patients, as compared with 10 out of 99 controls (p=4.86×10(-11), Odds Ratio 10.8); subsequent tiling microarray validated qPCR results and elucidated the fine structure of segmental gains. CONCLUSIONS A segmental copy-number gain in the IDI1/IDI2 gene region may play a significant role in the pathogenesis of SALS.