Peripheral Blood BRCA1 Methylation Positively Correlates with Major Alzheimer's Disease Risk Factors

BACKGROUND

Recent biomarker studies demonstrated that the central nervous system (CNS) environment can be observed from peripherally-derived samples. In a previous study, we demonstrated significant hypomethylation of the BRCA1 promoter region in neuronal cells from post-mortem brains of Alzheimer's disease patients through neuron-specific methylome analysis. Thus, we investigate the methylation changes in the BRCA1 promoter region in the blood samples.

OBJECTIVES

To analyze the methylation level of the BRCA1 promoter in peripheral blood from AD patients and normal controls.

DESIGN, SETTING, PARTICIPANTS

Genomic DNA samples from peripheral blood were obtained from the J-ADNI repository, and their biomarker data were obtained J-ADNI from the National Bioscience Database Center. Genomic DNA samples from an independent cohort for validation was obtained from Niigata University Hospital (Niigata, Japan). Amyloid positivity was defied by visual inspection of amyloid PET or a CSF Aβ42 value ≤ 333 pg/mL at the baseline.

MEASUREMENTS

Methylation level of the BRCA1 promoter was analyzed by pyrosequencing.

RESULTS

Compared to normal controls, methylation of the BRCA1 promoter in AD patients was not significantly changed; however, in AD patients, it showed a positive correlation with AD risk factors.

CONCLUSIONS

Our data confirmed the importance of cell-type specific methylome analysis and also suggested that environmental changes in the CNS can be detected by observing the peripheral blood, implying that the peripheral BRCA1 methylation level can be a surrogate for AD.

A Japanese Multicenter Study on PET and Other Biomarkers for Subjects with Potential Preclinical and Prodromal Alzheimer's Disease

BACKGROUND

PET (positron emission tomography) and CSF (cerebrospinal fluid) provide the "ATN" (Amyloid, Tau, Neurodegeneration) classification and play an essential role in early and differential diagnosis of Alzheimer's disease (AD).

OBJECTIVE

Biomarkers were evaluated in a Japanese multicenter study on cognitively unimpaired subjects (CU) and early (E) and late (L) mild cognitive impairment (MCI) patients.

MEASUREMENTS

A total of 38 (26 CU, 7 EMCI, 5 LMCI) subjects with the age of 65-84 were enrolled. Amyloid-PET and FDG-PET as well as structural MRI were acquired on all of them, with an additional tau-PET with 18F-flortaucipir on 15 and CSF measurement of Aβ1-42, P-tau, and T-tau on 18 subjects. Positivity of amyloid and tau was determined based on the positive result of either PET or CSF.

RESULTS

The amyloid positivity was 13/38, with discordance between PET and CSF in 6/18. Cortical tau deposition quantified with PET was significantly correlated with CSF P-tau, in spite of discordance in the binary positivity between visual PET interpretation and CSF P-tau in 5/8 (PET-/CSF+). Tau was positive in 7/9 amyloid positive and 8/16 amyloid negative subjects who underwent tau measurement, respectively. Overall, a large number of subjects presented quantitative measures and/or visual read that are close to the borderline of binary positivity, which caused, at least partly, the discordance between PET and CSF in amyloid and/or tau. Nine subjects presented either tau or FDG-PET positive while amyloid was negative, suggesting the possibility of non-AD disorders.

CONCLUSION

Positivity rate of amyloid and tau, together with their relationship, was consistent with previous reports. Multicenter study on subjects with very mild or no cognitive impairment may need refining the positivity criteria and cutoff level as well as strict quality control of the measurements.

Partial loss of function of colony-stimulating factor 1 receptor in a patient with white matter abnormalities

BACKGROUND AND PURPOSE

Mutations in colony-stimulating factor 1 receptor (CSF1R) cause adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). Patients with ALSP can be misdiagnosed as having acute ischemic stroke due to hyperintensity lesions on diffusion-weighted magnetic resonance imaging. Mutant CSF1R proteins identified in ALSP show a complete loss of autophosphorylation of CSF1R.

METHODS

We conducted mutation screening of CSF1R in 123 patients with definite acute ischemic cerebrovascular syndrome and positive family history of stroke. The pathogenicity of identified variants was evaluated using functional analyses. The levels of autophosphorylation of CSF1R in response to treatment with ligands of CSF1R were examined in cells transfected with wild-type and mutant CSF1R.

RESULTS

We identified eight CSF1R variants, six were known non-pathogenic polymorphisms, whereas the other two were missense variants inducing substitution of amino acid residues (p.Glu573Lys and p.Gly747Arg). Functional assay showed that the levels of autophosphorylation of p.Gly747Arg were similar to those of wild-type when treated with ligands. The autophosphorylation of p.Glu573Lys was detectable, but significantly decreased compared with those of wild-type CSF1R (P < 0.001, two-way anova with Bonferroni). The clinical presentation of the patient with p.Glu573Lys was consistent with cerebral embolism. The patient did not have typical clinical findings of ALSP. However, periventricular white matter abnormalities, unrelated to the recent infarct, were evident on brain magnetic resonance imaging.

CONCLUSIONS

In contrast to ALSP-associated missense mutations, CSF1R p.Glu573Lys variant in a patient with acute ischemic cerebrovascular syndrome showed a partial loss of autophosphorylation of CSF1R; its clinical significance warrants further investigation.

Diagnostic criteria for adult-onset leukoencephalopathy with axonal spheroids and pigmented glia due to CSF1R mutation

BACKGROUND AND PURPOSE

To establish and validate diagnostic criteria for adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) due to colony-stimulating factor 1 receptor (CSF1R) mutation.

METHODS

We developed diagnostic criteria for ALSP based on a recent analysis of the clinical characteristics of ALSP. These criteria provide 'probable' and 'possible' designations for patients who do not have a genetic diagnosis. To verify its sensitivity and specificity, we retrospectively applied our criteria to 83 ALSP cases who had CSF1R mutations (24 of these were analyzed at our institutions and the others were identified from the literature), 53 cases who had CSF1R mutation-negative leukoencephalopathies and 32 cases who had cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) with NOTCH3 mutations.

RESULTS

Among the CSF1R mutation-positive cases, 50 cases (60%) were diagnosed as 'probable' and 32 (39%) were diagnosed as 'possible,' leading to a sensitivity of 99% if calculated as a ratio of the combined number of cases who fulfilled 'probable' or 'possible' to the total number of cases. With regard to specificity, 22 cases (42%) with mutation-negative leukoencephalopathies and 28 (88%) with CADASIL were correctly excluded using these criteria.

CONCLUSIONS

These diagnostic criteria are very sensitive for diagnosing ALSP with sufficient specificity for differentiation from CADASIL and moderate specificity for other leukoencephalopathies. Our results suggest that these criteria are useful for the clinical diagnosis of ALSP.

Clinical and genetic characterization of adult-onset leukoencephalopathy with axonal spheroids and pigmented glia associated with CSF1R mutation

Background and purpose

The clinical characteristics of colony stimulating factor 1 receptor (CSF1R) related adult‐onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) have been only partially elucidated.

Methods

Clinical data from CSF1R mutation carriers who had been seen at our institutions or reported elsewhere were collected and analysed using a specific investigation sheet to standardize the data.

Results

In all, 122 cases from 90 families with CSF1R mutations were identified. The mean age of onset was 43 years (range 18–78 years), the mean age at death was 53 years (range 23–84 years) and the mean disease duration was 6.8 years (range 1–29 years). Women had a significantly younger age of onset than men (40 vs. 47 years, P = 0.0006, 95% confidence interval 3.158–11.177). There was an age‐dependent penetrance that was significantly different between the sexes (P = 0.0013). Motor dysfunctions were the most frequent initial symptom in women whose diseases began in their 20s. Thinning of the corpus callosum, abnormal signalling in pyramidal tracts, diffusion‐restricted lesions and calcifications in the white matter were characteristic imaging findings of ALSP. The calcifications were more frequently reported in our case series than in the literature (54% vs. 3%). Seventy‐nine per cent of the mutations were located in the distal part of the tyrosine kinase domain of CSF1R (102 cases). There were no apparent phenotype−genotype correlations.

Conclusions

The characteristics of ALSP were clarified. The phenotype of ALSP caused by CSF1R mutations is affected by sex.

Diagnostic Value of Brain Calcifications in Adult-Onset Leukoencephalopathy with Axonal Spheroids and Pigmented Glia

Adult-onset leukoencephalopathy with axonal spheroids and pigmented glia is a rare neurodegenerative disease resulting from mutations in the colony stimulating factor 1 receptor gene. Accurate diagnosis can be difficult because the associated clinical and MR imaging findings are nonspecific. We present 9 cases with intracranial calcifications distributed in 2 brain regions: the frontal white matter adjacent to the anterior horns of the lateral ventricles and the parietal subcortical white matter. Thin-section (1-mm) CT scans are particularly helpful in detection due to the small size of the calcifications. These calcifications had a symmetric "stepping stone appearance" in the frontal pericallosal regions, which was clearly visible on reconstructed sagittal CT images. Intrafamilial variability was seen in 2 of the families, and calcifications were seen at birth in a single individual. These characteristic calcification patterns may assist in making a correct diagnosis and may contribute to understanding of the pathogenesis of leukoencephalopathy.

Centrifugal microfluidic platform for single-cell level cardiomyocyte-based drug profiling and screening

Drug screening and profiling is an important phase in drug discovery, development, and marketing. However, some profiling tests are not routinely done because of the needed additional technical skills and costly maintenance, which leads to cases of unexpected side effects or adverse drug reactions (ADRs). This study presents the design and operation of a microfluidic chip for single-cell level drug screening and profiling as an alternative platform for this purpose. Centrifugation was utilized to trap isolated single and groups of primary cultured neonatal rat cardiomyocytes in the same chip. In the off-spin operation of the chip, the cells can be observed under a microscope and movies of the beat motion can be recorded. The beat profiles of the cells were generated by image correlation analysis of the recorded video to study the contractile characteristics (beating rate, beating strength, and inter-beat duration). By utilizing this non-invasive tool, long term continuous monitoring, right after trapping, was made possible and cell growth and dynamics were successfully observed in the chip. Media and liquid replacement does not require further centrifugation but instead utilizes capillary flow only. The effect of carbachol (100 μM) and isoproterenol (4 μg mL(-1)) on single cells and groups of cells was demonstrated and the feature for immunostaining (β-actin) applicability of the chip was revealed. Furthermore, these findings can be helpful for the headway of non-invasive profiling of cardiomyocytes and for future chip design and operation of high-throughput lab-on-a-chip devices.

Genes associated with the progression of neurofibrillary tangles in Alzheimer's disease

The spreading of neurofibrillary tangles (NFTs), intraneuronal aggregates of highly phosphorylated microtubule-associated protein tau, across the human brain is correlated with the cognitive severity of Alzheimer's disease (AD). To identify genes relevant to NFT expansion defined by the Braak stage, we conducted whole-genome exon array analysis with an exploratory sample set consisting of 213 human post-mortem brain tissue specimens from the entorinal, temporal and frontal cortices of 71 brain-donor subjects: Braak NFT stages 0 (N=13), I-II (N=20), III-IV (N=19) and V-VI (N=19). We identified eight genes, RELN, PTGS2, MYO5C, TRIL, DCHS2, GRB14, NPAS4 and PHYHD1, associated with the Braak stage. The expression levels of three genes, PHYHD1, MYO5C and GRB14, exhibited reproducible association on real-time quantitative PCR analysis. In another sample set, including control subjects (N=30), and in patients with late-onset AD (N=37), dementia with Lewy bodies (N=17) and Parkinson disease (N=36), the expression levels of two genes, PHYHD1 and MYO5C, were obviously associated with late-onset AD. Protein-protein interaction network analysis with a public database revealed that PHYHD1 interacts with MYO5C via POT1, and PHYHD1 directly interacts with amyloid beta-peptide 42. It is thus likely that functional failure of PHYHD1 and MYO5C could lead to AD development.

Identification of independent APP locus duplication in Japanese patients with early-onset Alzheimer disease

BACKGROUND

The occurrence of duplications of the amyloid precursor protein gene (APP) has been described in European families with early-onset familial Alzheimer disease (EO-FAD) and cerebral amyloid angiopathy. However, the contribution of APP duplication to the development of AD in other ethnic populations remains undetermined.

METHODS

The occurrence of APP duplication in probands from 25 families with FAD and 11 sporadic EO-AD cases in the Japanese population was examined by quantitative PCR and microarray-based comparative genomic hybridisation analyses. APP expression level was determined by real-time quantitative reverse-transcription (RT) PCR analysis using mRNA extracted from the peripheral blood of the patients.

RESULTS

We identified APP locus duplications in two unrelated EO-FAD families. The duplicated genomic regions in two patients of these families differed from each other. No APP duplication was found in the late-onset FAD families or sporadic EO-AD patients. The patients with APP duplication developed insidious memory disturbance in their fifties without intracerebral haemorrhage and epilepsy. Quantitative RT-PCR analysis showed the increased APP mRNA expression levels in these patients compared with those in age- and sex-matched controls.

CONCLUSIONS

Our results suggest that APP duplication should be considered in patients with EO-FAD in various ethnic groups, and that increased APP mRNA expression level owing to APP duplication contributes to AD development.

BubR1 localizes to centrosomes and suppresses centrosome amplification via regulating Plk1 activity in interphase cells

BubR1 is a critical component of the mitotic checkpoint that delays the onset of anaphase until all chromosomes have established bipolar attachment to the microtubules. We previously reported that mutations of the BUB1B gene (encoding BubR1) caused premature chromatid separation (PCS) syndrome, a condition characterized by constitutional aneuploidy and a high risk of childhood cancer. We here report that the cells from PCS syndrome patients have loss of regulation of the centrosome duplication machinery, resulting in centrosome amplification and multipolar mitosis. PCS syndrome cells show increased activity of Polo-like kinase 1 (Plk1), whose knockdown suppresses centrosome amplification. BubR1 localizes to centrosomes, physically interacts with Plk1 and inhibits Plk1 phosphorylation and its kinase activity during interphase. These results unravel a crucial role of BubR1 in preventing centrosome reduplication through negative regulation of Plk1 in interphase cells.

Total deletion and a missense mutation of ITPR1 in Japanese SCA15 families

BACKGROUND

Spinocerebellar ataxia type 15 (SCA15) is a progressive neurodegenerative disorder characterized by pure cerebellar ataxia, very slow progression, and distinct cerebellar atrophy. The locus for SCA15 was first mapped to 3p24.2-3pter in an Australian family. We have subsequently mapped two Japanese families presenting with ataxia and postural tremor of the head, arm, or trunk to the SCA15 locus. Recently, partial deletions involving both the type 1 inositol 1,4,5-triphosphate receptor (ITPR1) and sulfatase modifying factor 1 (SUMF1) genes have been identified in Australian and British families with SCA15.

METHODS

We conducted fine haplotype analysis on the region including ITPR1. To identify the deletion, we conducted gene dosage analysis and array-based comparative genomic hybridization (aCGH) analysis. Gene expression analysis was performed using quantitative real-time reverse transcription PCR. Mutational analyses of ITPR1 and SUMF1 were also performed.

RESULTS

We have identified a 414-kb deletion including the entire ITPR1 and exon 1 of SUMF1 in patients in family A. The expression levels of ITPR1 and SUMF1 mRNAs of the patient were half those of the normal control. Furthermore, in family B, we have identified a C-to-T substitution at position 8581 of ITPR1, resulting in the amino acid substitution of leucine for proline at codon 1059, which is highly conserved among species.

CONCLUSIONS

Our results strongly confirm that ITPR1 is the causative gene for SCA15 and suggest that we need to investigate the point mutation in ITPR1 in the patients with autosomal dominant cerebellar ataxia and tremor.

[The clinical-genealogic and molecular-genetic characteristics of oculopharyngeal muscular dystrophy in the Republic of Sakha (Yakutia)]

The clinical-genealogic and molecular-genetic investigation of oculopharyngeal muscular dystrophy (OPMD) in the Republic of Sakha (Yakutia) was performed. It was investigated 33 unrelated Yakut families with 38 patients and 2 russian families with 2 patients and 59 their healthy relatives as well. The high clinical polymorphism of disease was found in patients with OPMD. The mutation in exon 1 of the PABPN1 gene resulting in the expansion of GCG-repeats up to 10 is revealed. Using direct sequencing of the PABPN1 gene in 17 families (16 Yakut, 1 Russian), we identified a type of this mutation as an insertion of 4 GCG-repeats. Frequency of OPMD in the Yakut population is 1:11 680 that is 10-20 times higher comparing to european populations. This is a first report on the patients with OPMD from the Republic of Sakha with diagnosis confirmed by molecular-genetic analysis.

Clinical, molecular and histopathological features of short stature syndrome with novel CUL7 mutation in Yakuts: new population isolate in Asia

BACKGROUND

In total, 43 patients having short stature syndrome in 37 Yakut families with autosomal recessive prenatal and postnatal nonprogressive growth failure and facial dysmorphism but with normal intelligence have been identified.

METHODS

Because Yakuts are considered as a population isolate and the disease is rare in other populations, genomewide homozygosity mapping was performed using 763 microsatellite markers and candidate gene approach in the critical region to identify the causative gene for the short stature syndrome in Yakut.

RESULTS

All families shared an identical haplotype in the same region as the identical loci responsible for 3-M and gloomy face syndromes and a novel homozygous 4582insT mutation in Cullin 7 (CUL7) was found, which resulted in a frameshift mutation and the formation of a subsequent premature stop codon at 1553 (Q1553X). Yakut patients with short stature syndrome have unique features such as a high frequency of neonatal respiratory distress and few bone abnormalities, whereas the clinical features of the other Yakut patients were similar to those of 3-M syndrome. Furthermore, abnormal vascularisation was present in the fetal placenta and an abnormal development of cartilage tissue in the bronchus of a fetus with CUL7 mutation.

CONCLUSION

These findings may provide a new understanding of the clinical diversity and pathogenesis of short stature syndrome with CUL7 mutation.

Generation of intracellular domain of insulin receptor tyrosine kinase by gamma-secretase

The proteolytic cleavage of a precursor protein into alpha- and beta-subunits by furin is required to form functional insulin receptor (IR). In this study, we examined if IR undergoes the additional presenilin (PS)/gamma-secretase-dependent processing. In cells treated with gamma-secretase inhibitors or expressing the dominant-negative PS1 variant led to the accumulation of an endogenous IR C-terminal fragment. In the presence of proteasome inhibitors, we detected a PS/gamma-secretase cleavage product of the IR, termed the IR intracellular domain (ICD). Cellular fractionation and confocal microscopy analyses showed that the IR-ICD is predominantly detected in the nucleus. These data indicate that IR is a tyrosine kinase receptor, which undergoes PS/gamma-secretase-dependent processing. We also show that the autophosphorylation levels of the IR beta-subunit upon insulin stimulation were decreased by the inactivation of PS/gamma-secretase, raising the possibility that the PS/gamma-secretase proteolysis of IR may play a modulatory role in insulin signaling.

Synthesis and cancer antiproliferative activity of new histone deacetylase inhibitors: hydrophilic hydroxamates and 2-aminobenzamide-containing derivatives

New series histone deacetylase inhibitors comprising a hydroxamic acid or 2-aminobenzamide group as a zinc-chelating function were synthesized and evaluated for antiproliferative activities against a panel of human cancer cells. The 2-aminobenzamide series inhibitors generally had the potency in cell growth inhibitions comparable to that of MS-275. Among them, the compound having a (3,4-difluorobenzyl)(2-hydroxyethyl)amino group at one end and a 2-aminobenzamide group at the other of molecule showed the most promising profile as an anticancer drug candidate, since it had a comparatively low toxicity as did MS-275 against a normal fibroblast cell CCD-1059SK. Additionally, the derivative exhibited a high recovery in human plasma stability test.

Spastic paraplegia, ataxia, mental retardation (SPAR): a novel genetic disorder

OBJECTIVE

To describe a kindred with a dominantly inherited neurologic disorder manifested either as uncomplicated spastic paraplegia or ataxia, spastic paraplegia, and mental retardation.

METHODS

Neurologic examinations and molecular genetic analysis (exclusion of known SCA and HSP genes and loci; and trinucleotide repeat expansion detection [RED]) were performed in six affected and four unaffected subjects in this family. MRI, electromyography (EMG), and nerve conduction studies were performed in three affected subjects.

RESULTS

The phenotype of this dominantly inherited syndrome varied in succeeding generations. Pure spastic paraplegia was present in the earliest generation; subsequent generations had ataxia and mental retardation. MRI showed marked atrophy of the spinal cord in all patients and cerebellar atrophy in those with ataxia. Laboratory analysis showed that the disorder was not caused by mutations in genes that cause SCA-1, SCA-2, SCA-3, SCA-6, SCA-7, SCA-8, and SCA-12; not linked to other known loci for autosomal dominant ataxia (SCA-4, SCA-5, SCA-10, SCA-11, SCA-13, SCA-14, and SCA-16); and not linked to known loci for autosomal dominant hereditary spastic paraplegia (HSP) (SPG-3, SPG-4, SPG-6, SPG-8, SPG-9, SPG-10, SPG-12, and SPG-13) or autosomal recessive HSP SPG-7. Analysis of intergenerational differences in age at onset of symptoms suggests genetic anticipation. Using RED, the authors did not detect expanded CAG, CCT, TGG, or CGT repeats that segregate with the disease.

CONCLUSIONS

The authors describe an unusual, dominantly inherited neurologic disorder in which the phenotype (pure spastic paraplegia or spastic ataxia with variable mental retardation) differed in subsequent generations. The molecular explanation for apparent genetic anticipation does not appear to involve trinucleotide repeat expansion.

Characterization of a presenilin-mediated amyloid precursor protein carboxyl-terminal fragment gamma. Evidence for distinct mechanisms involved in gamma -secretase processing of the APP and Notch1 transmembrane domains

A variety of investigations have led to the conclusion that presenilins (PS) play a critical role in intramembranous, gamma-secretase proteolysis of selected type I membrane proteins, including Notch1 and amyloid precursor protein (APP). We now show that the generation of the S3/Notch intracellular domain and APP-carboxyl-terminal fragment gamma (CTFgamma) derivatives are dependent on PS expression and inhibited by a highly selective and potent gamma-secretase inhibitor. Unexpectedly, the APP-CTFgamma derivative is generated by processing between Leu-645 and Val-646 (of APP(695)), several amino acids carboxyl-terminal to the scissile bonds for production of amyloid beta protein peptides. Although the relationship of APP-CTFgamma to the production of amyloid beta protein peptides is not known, we conclude that in contrast to the highly selective PS-dependent processing of Notch, the PS-dependent gamma-secretase processing of APP is largely nonselective and occurs at multiple sites within the APP transmembrane domain.

Cancer-prone syndrome of mosaic variegated aneuploidy and total premature chromatid separation: report of five infants

Five infants (two girls and three boys) from four families all had severe pre- and postnatal growth retardation, profound developmental delay, microcephaly, hypoplasia of the brain with Dandy-Walker complex or other posterior fossa malformations, and developed uncontrollable clonic seizures. Four infants developed Wilms tumors, and one showed cystic lesions in bilateral kidneys. All five infants showed variegated mosaic aneuploidy in cultured lymphocytes. In two infants whose chromosomes were prepared by us, 48.5%-83.2% lymphocytes showed total premature chromatid separation (PCS). Their parents had 3.5%-41.7% of their lymphocytes in total PCS. The remaining three infants and their parents, whose chromosomes were prepared at outside laboratories, tended to show lower frequencies of total PCS. Another five infants reported with the disorder were reviewed together with the five infants we described. Together, their clinical and cytogenetic manifestations were similar enough to suggest a syndrome. Seven of the 10 infants developed proven or probable Wilms tumors. The age at diagnosis of the tumors was younger than usual at 2-16 months. The tumors were bilateral in four infants and unilateral in three infants, and cystic changes were present in six infants. Two infants developed botryoid rhabdomyosarcoma. The carriers of the syndrome are thus liable to tumorigenesis. The possible role of mitotic checkpoint defects, proven in two infants with the syndrome (Matsuura et al. [2000: Am J Hum Genet 69:483-486]), was discussed in connection with tumor development and progression.

Physiological and pharmacological role of lysophosphatidic acid as modulator in mechanotransduction

The mechanotransduction mechanism is believed to play an important role in maintenance of cellular homeostasis in a wide variety of cell types. In particular, the mechanotransduction system in vascular endothelial cells may be an essential mechanism for local hemodynamic control. Elevations in intracellular free Ca2+ concentration ([Ca2]i) are an important signal in the initial step of mechanotransduction and mechanosensitive (MS) cation channels are thought to be a putative pathway; however, the molecular mechanisms remain unclear. We found that lysophosphatidic acid (LPA), a bioactive phospholipid, sensitizes the response of [Ca2+]i to mechanical stress in several cell types. Employing real-time confocal microscopy, local increases in [Ca2+]i in several regions within the cell during application of mechanical stress were clearly visualized in bovine lens epithelial and endothelial cells in the presence of LPA. The phenomenon was termed "Ca2+ spots". Pharmacological studies revealed that Ca2+ spots arise due to influx through MS channels. In this report, our data indicating the possible significance of LPA as an endogenous factor involved in regulation of mechanotransduction is reviewed. Furthermore, our findings suggest that the Ca2+ spot is a novel phenomenon occurring as an elementary Ca2+-influx event through MS channels directly coupled with the initial step in mechanotransduction.

Nicotine-induced phosphorylation of extracellular signal-regulated protein kinase and CREB in PC12h cells

We have investigated mechanisms of nicotine-induced phosphorylation of extracellular signal-regulated protein kinase (p42/44 MAP kinase, ERK) and cAMP response element binding protein (CREB) in PC12h cells. Nicotine transiently induced ERK phosphorylation at more than 1 microM. The maximal level of nicotine-induced ERK phosphorylation was lower than that of the membrane depolarization induced and, to a great extent, the nerve growth factor (NGF)-induced ERK phosphorylation. Nicotinic acetylcholine receptor (nAChR) alpha7 subunit-selective inhibitors had no significant effect on nicotine-induced ERK phosphorylation. L-Type voltage-sensitive calcium channel antagonists inhibited nicotine-induced ERK phosphorylation. Calcium imaging experiments showed that alpha7-containing nAChR subtypes were functional at 1 microM of nicotine in the nicotine-induced calcium influx, and non-alpha7 nAChRs were prominent in the Ca(2+) influx at 50 microM of nicotine. An expression of dominant inhibitory Ras inhibited nicotine-induced ERK phosphorylation. A calmodulin antagonist, a CaM kinase inhibitor, a MAP kinase kinase inhibitor inhibited nicotine-induced ERK and CREB phosphorylation. The time course of the phosphorylation of CREB induced by nicotine was similar to that of ERK induced by nicotine. These results suggest that non-alpha7 nAChRs are involved in nicotine-induced ERK phosphorylation through CaM kinase and the Ras-MAP kinase cascade and most of the nicotine-induced CREB phosphorylation is mediated by the ERK phosphorylation in PC12h cells.

Roles of TT virus infection in various types of chronic hepatitis

An unenveloped single-stranded virus, which might be a causative agent for posttransfusion non-A-G hepatitis, was recently found and named "TT virus" (TTV). There is still controversy over the role of TTV in chronic hepatitis. Therefore, we have examined the prevalence of TTV in various types of chronic hepatitis in Japan. TTV DNA was detected in 11 of 40 patients (27.5%) with non-B, non-C chronic hepatitis, 13 of 46 patients (28.3%) with type B chronic hepatitis, 21 of 55 patients (38.2%) with type C chronic hepatitis, and 41 of 131 subjects (31.3%) with normal liver function tests. The positivity rate for TTV DNA tended to increase with age. The detection rate did not differ statistically between non-B, non-C chronic hepatitis and type B or type C chronic hepatitis, or normal subjects. The distribution of TTV genotypes was not significantly different among them. Clinical characteristics of the chronic illness were similar for patients with or without TTV in all hepatitis groups. The etiologic role of TTV in chronic hepatitis is not confirmed from the statistical and clinical standpoint.

Dentatorubral-pallidoluysian atrophy (DRPLA) presenting with psychosis

The authors report on four DRPLA patients who manifested delusions. All patients demonstrated autosomal dominant DRPLA confirmed by standard gene analysis. Patients with DRPLA can exhibit a variety of psychiatric symptoms in addition to extrapyramidal and cerebellar symptoms.

Differences in survival-promoting effects and intracellular signaling properties of BDNF and IGF-1 in cultured cerebral cortical neurons

Brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1) act on various neurons of the CNS as neurotrophic factors promoting neuronal differentiation and survival. We examined the survival-promoting effects of BDNF and IGF-1 on serum deprivation-induced death in cultured cerebral cortical neurons, and compared the intracellular signaling pathways stimulated by BDNF and IGF-1 in the neurons. We found that the survival-promoting effect of BDNF was much weaker than that of IGF-1 in serum deprivation-induced death of cultured cortical neurons. We found no differences in the levels of phosphatidylinositol 3-kinase (PtdIns3-K) activity or Akt (also called PKB) phosphorylation induced by BDNF and IGF-1 in the cultured cortical neurons, although many reports suggest that PtdIns3-K and Akt are involved in survival promotion. In addition, phosphorylation signals of mitogen-activated protein kinase (MAPK) and cAMP responsive element-binding protein (CREB), which have also been reported to be involved in survival promotion, were stimulated by BDNF much more potently than by IGF-1. These results show that there may be, as yet unidentified, intracellular signaling pathways other than the PtdIns3-K-Akt, MAPK and CREB signaling, to regulate survival promotion. These unidentified signaling pathways may be responsible for the distinct strengths of the survival-promoting effects of BDNF and IGF-1.

Analysis of the expression level of alpha-synuclein mRNA using postmortem brain samples from pathologically confirmed cases of multiple system atrophy

To determine whether multiple system atrophy (MSA) is associated with altered expression levels of the alpha-synuclein messenger RNA (mRNA), we performed quantitative reverse transcription polymerase chain reaction for alpha-synuclein mRNA using postmortem brain samples from 11 cases of MSA and 14 age-matched control subjects. The brain specimens used in this study contained both the gray matter and white matter, which were dissected from the frontal, temporal or occipital lobe. The expression levels of alpha-synuclein mRNA in the brain specimens of MSA cases were not different from those of the control subjects. These results suggest that the transcriptional regulation of the alpha-synuclein gene is unlikely to be affected in MSA brains.

Analysis of tyrosine phosphorylation-dependent protein-protein interactions in TrkB-mediated intracellular signaling using modified yeast two-hybrid system

Activated receptor tyrosine kinases induce a large number of tyrosine phosphorylation-dependent protein-protein interactions through which they mediate their various ligand-exerted functions including regulation of proliferation, differentiation and survival. TrkB receptor tyrosine kinase activated by binding of brain-derived neurotrophic factor (BDNF) also stimulates various protein interactions in a tyrosine phosphorylation-dependent manner in neuronal cells. To examine tyrosine phosphorylation-dependent interactions stimulated by active TrkB, we developed a modified yeast two-hybrid system, which we call the yeast two-and-a-half-hybrid system. In this system, yeast was engineered to express a tyrosine kinase domain of TrkB as an effector, in addition to two fusion proteins with GAL4 DNA-binding and GAL4 activation domains as bait and prey proteins, respectively. Using this system with Shp2 as the bait, we demonstrated that Shp2 interacts directly with BIT/SHPS-1 (also called SIRP) and Grb2 depending on tyrosine phosphorylation mediated by TrkB. Furthermore, we screened an adult human brain cDNA library with the yeast two-and-a-half-hybrid system in order to identify other Shp2-binding proteins in TrkB-stimulated tyrosine phosphorylation signaling. We found that fibroblast growth factor receptor substrate 2beta (FRS2beta), also called SNT2, interacts with Shp2 dependently on TrkB-mediated tyrosine phosphorylation of FRS2beta/SNT2. Therefore, we show that the two-and-a-half-hybrid system is a powerful tool for studying tyrosine phosphorylation-dependent protein-protein interactions in intracellular signaling pathways stimulated by TrkB receptor tyrosine kinase.

Lysophosphatidic acid positively regulates the fluid flow-induced local Ca(2+) influx in bovine aortic endothelial cells

Using real-time confocal microscopy, we have demonstrated that lysophosphatidic acid (LPA), a bioactive phospholipid existing in plasma, positively regulates fluid flow-induced [Ca(2+)](i) response in fluo 4-loaded, cultured, bovine aortic endothelial cells. The initial increase in [Ca(2+)](i) was localized to a circular area with a diameter of <4 microm and spread concentrically, resulting in a mean global increase in [Ca(2+)](i). The local increase often occurred in a stepwise manner or repetitively during constant flow. The percentage of cells that responded and the averaged level of increase in [Ca(2+)](i) were dependent on both the concentration of LPA (0.1 to 10 micromol/L) and the flow rate (25 to 250 mm/s). The response was inhibited by removing extracellular Ca(2+) or by the application of Gd(3+), an inhibitor of mechanosensitive (MS) channels, but not by thapsigargin, an inhibitor of the endoplasmic reticular Ca(2+)-ATPASE: It was also inhibited by 8-bromo-cGMP, and the inhibition was completely reversed by KT5823, an inhibitor of protein kinase G (PKG). These results suggest that the [Ca(2+)](i) response arises from Ca(2+) influx through Gd(3+)-sensitive MS channels, which are negatively regulated by the activation of PKG. The spatiotemporal properties of the [Ca(2+)](i) response were completely different from those of a Ca(2+) wave induced by ATP, a Ca(2+)-mobilizing agonist. Therefore, we called the phenomenon Ca(2+) spots. We conclude that LPA positively regulates fluid flow-induced local and oscillatory [Ca(2+)](i) increase, ie, the Ca(2+) spots, in endothelial cells via the activation of elementary Ca(2+) influx through PKG-regulating MS channels. This indicates an important role for LPA as an endogenous factor in fluid flow-induced endothelial function.

Two subtypes of androgen and progestogen receptors in fish testes

Two subtypes (alpha and beta) of androgen (AR) and progestogen receptors (PR) are present in the testis of Japanese eel (Anguilla japonica). Amino acid homology of the open reading frames between alpha and beta in AR or PR is approximately 40%, but the DNA- and ligand-binding domains show high homology between subtypes. Judging from these structures, alpha and beta are not isoforms derived from translational initiation at two in-phase ATG codons, alternative splicing, or tetraploidy. In transient transfection assays using a reporter construct containing a steroid-responsive promoter, each subtype showed its corresponding hormone-dependent transactivation. The ligand affinity for transactivation between AR and PR subtypes was similar for physiological ligands. Tissue distribution of both subtype mRNAs was different. Protein interaction between subtypes was demonstrated in vitro by GST pull-down assays. These results clearly indicate that two functional subtypes of AR and PR exist in eel. These findings will advance our understanding of the mechanisms underlying sex steroid signaling.

Effect of D-glucose on induction of xylose reductase and xylitol dehydrogenase in Candida tropicalis in the presence of NaCl

Xylitol production is suppressed by D-glucose. We previously reported that the suppression was abrogated in the presence of NaCl. This was explained in part by high levels of xylose reductase (XR) activity. In this study, we investigated the effects of D-glucose on XR and xylitol dehydrogenase (XDH) induction in Candida tropicalis in the presence of NaCl. We examined the time courses of these activities under the following conditions: 50 mg/ml D-xylose, 20-80 mg/ml D-glucose and 40 mg/ml NaCl. The level of XR increased in the presence of 40 mg/ml NaCl, whereas that of XDH was not affected by NaCl. The effects of NaCl upon XR and XDH induction suggest that the synthesis of both enzymes is not under a coordinate control. The expression of XR is suppressed by D-glucose. In the absence of NaCl, suppression continued even after D-glucose was completely consumed, while in the presence of 40 mg/ml NaCl, suppression stopped after the consumption of D-glucose.

p38 mitogen-activated protein kinase regulates low potassium-induced c-Jun phosphorylation and apoptosis in cultured cerebellar granule neurons

Cultured rat cerebellar granule neurons are widely used as a model system for studying neuronal apoptosis. After maturation by culturing in medium containing 26 mm potassium (high K(+)), changing to medium containing 5 mm potassium (low K(+); LK) rapidly induces neuronal apoptosis. Then over 50% of granule cells die within 24 h. However, the molecular mechanisms by which the LK-induced apoptosis occurs in cultured cerebellar granule cells remain unclear. In the present study, we found that p38 MAP kinase (p38) was an important factor for LK-induced apoptosis. Three hours after changing to LK medium, p38 was markedly activated. In addition, SB203580, a specific inhibitor of p38, strongly inhibited the phosphorylation and expression of c-Jun in LK-induced apoptosis of cultured cerebellar granule cells. In vitro kinase assay using glutathione S-transferase-c-Jun as a substrate showed that p38 directly phosphorylated c-Jun. Furthermore, in the presence of SB203580, about 80% of neurons survived. These results indicate that p38 regulates LK-induced apoptosis of cerebellar granule neurons.

Effects of simulated microgravity on mammalian fertilization and preimplantation embryonic development in vitro

OBJECTIVE

To study the effects of simulated microgravity on mammalian fertilization and preimplantation embryonic development in vitro with the use of a horizontal clinostat device.

DESIGN

Controlled animal study.

SETTING

Research laboratory at a university medical school.

ANIMAL(S)

B6D2F1 (C57BL/6 x DBA/2) and ICR mice between 8 and 10 weeks old.

INTERVENTION(S)

The first experiment was performed to investigate whether gravity is required for fertilization in vitro under three conditions: clinostat rotation, rotational control, and stationary control. In the second experiment, one-cell embryos were cultured under each condition and their morphology and viability were assessed at 96 hours.

MAIN OUTCOME MEASURE(S)

The fertilized numbers and embryonic numbers at the morula and blastocyst stages were recorded in each condition.

RESULT(S)

In the first experiment, there were no statistically significant differences in the efficiency of achieving normal fertilization in vitro among the conditions. In the second experiment, there was a statistically significant decrease in the number of embryos reaching the morula and blastocyst stages after 96 hours in culture under clinostat rotation.

CONCLUSION(S)

These results suggest that the process of fertilization in vitro is not sensitive to the gravitational vector. However, the possibility exists that the frequency of early embryonic lethality is increased by microgravity.

The prevalence of TT virus infection in renal transplant recipients in Brazil

BACKGROUND

Recently, TT virus (TTV) was discovered as a potential causative agent for non-A-E hepatitis. Little is known about the prevalence of TTV infection in renal transplant recipients.

METHODS

One hundred and seventeen Brazilian renal transplant recipients and 100 normal subjects were examined to determine the prevalence of TTV infection. The TTV DNA in serum and its genotype were examined using polymerase chain reaction and restriction enzyme length polymorphism, respectively.

RESULTS

TTV DNA was detected in 63/117 (53.8%) renal transplant recipients in contrast to its detection in 10/100 (10%) normal subjects (P<0.001). There was no statistical difference in the distribution of TTV genotypes between these groups. There was no significant difference in clinical backgrounds between TTV positive and negative patients.

CONCLUSIONS

These results indicate a risk for TTV infection in renal transplant recipients in Brazil. They also indicate that TTV itself might not have a strong correlation with the pathogenicity of liver diseases.

Expanded polyglutamine stretches interact with TAFII130, interfering with CREB-dependent transcription

At least eight inherited neurodegenerative diseases are caused by expanded CAG repeats encoding polyglutamine (polyQ) stretches. Although cytotoxicities of expanded polyQ stretches are implicated, the molecular mechanisms of neurodegeneration remain unclear. We found that expanded polyQ stretches preferentially bind to TAFII130, a coactivator involved in cAMP-responsive element binding protein (CREB)-dependent transcriptional activation, and strongly suppress CREB-dependent transcriptional activation. The suppression of CREB-dependent transcription and the cell death induced by polyQ stretches were restored by the co-expression of TAFII130. Our results indicate that interference of transcription by the binding of TAFII130 with expanded polyQ stretches is involved in the pathogenetic mechanisms underlying neurodegeneration.

Two phenotypes and anticipation observed in Japanese cases with early onset torsion dystonia (DYT1) - pathophysiological consideration

Early onset torsion dystonia (DYT1) is a dominantly inherited dystonia caused by a deletion of three bases, GAG, coding glutamic acid, in chromosome 9q34. The protein coded by this gene was named as torsin A. DYT1 is common among the Ashkenazi Jewish population, but has been thought to be rare among Japanese. Among the idiopathic torsion dystonias being followed in this clinic, we found five families with DYT1 by gene analysis. This is the first report of genetically proven Japanese DYT1.The clinical features of five proband cases were divided into two types. One type is postural dystonia with marked trunkal torsion, and the other is action dystonia associated with violent dyskinetic movements. The affected family members in the upper generations presented with focal or segmental dystonia; it was postural dystonia of the legs in the former, and writer's cramp or tremor of the arms in the latter families. There was an asymptomatic carrier in the upper generation. Anticipation in the age of onset and severity of the disease was observed in all families. Medical treatment, including anticholinergics and levodopa, did not show apparent effects, while stereotactic thalamotomy to the nucleus ventralis lateralis (VL) or ventralis intermedius (Vim), with or without posterior ventral pallidotomy, were effective with action dystonia, but not postural dystonia. This study suggests the existence of at least two phenotypes in DYT1, in which different pathways of the basal ganglia are involved.

Novel mutations, pseudo-dominant inheritance, and possible familial affects in patients with autosomal recessive juvenile parkinsonism

Autosomal recessive juvenile parkinsonism is a hereditary neurodegenerative disorder, usually beginning before the age of 40. We found three exonic deletions and two novel point mutations (Arg33Stop and Cys431Phe) in six families with autosomal recessive juvenile parkinsonism. In 1 family, in which an autosomal dominant mode of inheritance was suspected, multiple mutant alleles were identified. Although a wide range of ages at onset was observed, there was no correlation between age at onset and genotype.

Brain-derived neurotrophic factor accelerates nitric oxide donor-induced apoptosis of cultured cortical neurons

Brain-derived neurotrophic factor (BDNF) is known to have important functions in neuronal survival, differentiation, and plasticity. In addition to its role as a survival-promoting factor, BDNF reportedly can enhance neuronal cell death in some cases, for example, the death caused by excitotoxicity or glucose deprivation. The cellular mechanism of the death-enhancing effect of BDNF remains unknown, in contrast to that of its survival-promoting effect. In this work, we found that BDNF markedly accelerated the nitric oxide (NO) donor-induced death of cultured embryonic cortical neurons. BDNF increased the number of cells with nuclear condensation and DNA fragmentation 24 h after treatment with the NO donor, but it did not change the number of those cells 36 h after the treatment. The BDNF-accelerated death of cortical neurons was inhibited by the addition of actinomycin D or cycloheximide. These results suggest that BDNF can accelerate apoptotic cell death elicited by NO donor. TrkB-IgG and K252a blocked the BDNF-induced acceleration of the death, indicating that the death-accelerating effect by BDNF is mediated by TrkB. In addition, the BDNF-accelerated apoptosis was inhibited by the addition of SB202190 and SB203580, specific inhibitors of p38 mitogen-activated protein kinase (MAPK), and U0126, a specific inhibitor of MAPK/ERK kinase 1, indicating that the activation of both p38 MAPK and ERK is involved in the signaling cascade of the BDNF-accelerated, NO donor-induced apoptosis.

A CAG trinucleotide repeat expansion and familial schizophrenia

Studies which showed anticipation in families with schizophrenia suggested that a trinucleotide repeat expansion mechanism may be involved in the pathogenesis of familial schizophrenia. Furthermore, some studies involving the repeat expansion detection (RED) method showed the median length of CAG repeats to be longer in probands with schizophrenia than that in control subjects. We screened for a possible expanded CAG repeat by means of the direct identification of repeat expansion and cloning technique in 23 subjects (affected, 14; unaffected, 9) from six families with schizophrenia which showed anticipation. The polymorphism of a long and unstable CAG/CTG trinucleotide repeat, Dir1, was studied by PCR. No unusual expanded CAG/CTG trinucleotide repeat was detected in the subjects with familial schizophrenia. There was no significant difference between the affected and unaffected subjects in the allele frequency of Dir1. Our results suggest that a CAG expansion is not the mechanism underlying familial schizophrenia.

A novel PTEN mutation in a Japanese patient with Cowden disease

Cowden disease (CD) is an autosomal dominant syndrome characterized by multiple hamartomatous lesions and an increased risk for malignancies. Recent evidence has indicated that the PTEN gene, encoding a protein tyrosine phosphatase, is the CD susceptibility gene. However, another line of evidence has suggested that CD might be genetically heterogeneous. Clinical features of CD are variable, and there are interfamilial differences in the expression of skin lesions. Therefore, information on PTEN mutations in CD patients should be accumulated to clarify the genotype-phenotype correlation. In the present study, we found heterozygous germline mutations of PTEN in all of three Japanese patients with CD examined, indicating no genetic heterogeneity among our patients. The mutations included two non-sense mutations of R335X and R130X, and a mis-sense mutation of C136R. To the best of our knowledge, the C136R mutation has not previously been reported in CD patients. This novel mutation was located outside the core motif of the phosphatase domain of PTEN protein, where most of the missense mutations previously reported in CD patients were clustered. Mucocutaneous manifestations were far fewer in the patient with this mutation than in the patients with nonsense mutations. Whether the phenotypic difference in mucocutaneous features was due to the different mutations remains unclear.

Regulation of alpha3 nicotinic acetylcholine receptor subunit mRNA levels by nerve growth factor and cyclic AMP in PC12 cells

To investigate the effects of nerve growth factor (NGF) and cyclic AMP (cAMP) on the level of the nicotinic acetylcholine receptor subunit alpha3 mRNA, we used PC12h cells, PC12 cells expressing dominant-negative Ras protein, and the parental PC12 cells. PC12h cells have NGF-responsive tyrosine hydroxylase activity. Expression of dominant-negative Ras protein prevents the signaling through the Ras-mitogen-activated protein kinase cascade. The morphological changes of the parental PC12 cells in response to NGF and 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate (CPTcAMP), a cell-penetrating cAMP analogue, were similar to those of PC12h cells. NGF up-regulated the alpha3 mRNA level in PC12h cells and down-regulated the alpha3 mRNA level in the parental PC12 cells. Expression of dominant-negative Ras protein and an inhibitor of mitogen-activated protein kinase kinase inhibited the effects of NGF on alpha3 mRNA level. CPTcAMP down-regulated the alpha3 mRNA level in all three PC12 cell lines. An inhibitor of protein kinase A inhibited the CPTcAMP-induced down-regulation of alpha3 mRNA. The alpha3 mRNA down-regulation required prolonged treatment with CPTcAMP even after cAMP response element binding protein phosphorylation was decreased. Membrane depolarization with high K+ had no effect on the alpha3 mRNA level in PC12h cells. Based on these results, we propose that at least two unknown effectors regulate alpha3 mRNA levels in PC12 cells.