Van Swieten Research Articles

Abstract 3212: Aggravated Intraventricular Hemorrhage and White Matter Lesions: A Nationwide Cohort of Intracerebral Hemorrhage Patients

Background. Intraventricular hemorrhage (IVH) secondary to intracerebral hemorrhage (ICH) is an important indicator of poor outcome. Location and size of hematoma have been known to associate with IVH, but other clinical and neuroimaging predictors are yet to be discovered. Among them, white matter lesion (WML), which reflects accumulation of chronic sublethal ischemic injuries and periventricular edema, may signify vulnerability of individual brain, hence being associated with development and aggravation of IVH. Methods. A total of 1,604 ICH patients were collected through 33 stroke centers in South Korea with nationwide coverage. We excluded 199 subjects whose computed tomography (CT) scans were taken more than 48 hours after symptom onset, 89 subjects whose images were of poor quality, 42 subjects who had primary IVH without ICH and 12 subjects who were misclassified. Finally, 1,262 acute ICH patients were included in our analysis dataset. Clinical, laboratory, and imaging information was collected during admission. Experienced stroke neurologists independently reviewed CT scans of included patients for rating WML (van Swieten method) and IVH scores, with good inter-rater agreements. IVH score is a recently proposed semi-quantitative and validated method for estimating volume of IVH. Functional outcomes included Glasgow coma scale score and mortality status at the end of 2006. Results. Among the 1,262 ICH patients, 343 subjects (27.2%) were found to have IVH. Patients with IVH are older and had higher level of blood glucose and ICH volume. The proportion of subjects with extensive WML was significantly higher in patients with IVH then those without IVH (33.8% vs. 16.3%; P <0.01). The association between WML and IVH remained significant after controlling for relevant covariates (OR 1.43 and 95% CI 1.02 - 2.02 for mild WML; OR 2.66 and 95% CI 1.83 - 3.87 for extensive WML; compared to no WML). Estimated mean of IVH score of extensive WML group was also significantly higher than that of no WML group (estimated mean ± standard error; 11.5 ± 0.5 vs 9.4 ± 0.5; P =0.01 from analysis of covariance with Tukey’s post-hoc multiple comparison). For outcomes after ICH, presence of IVH was associated with increased odds of having surgical management (OR 3.48 and 95% CI 2.54 - 4.76), lower Glasgow coma scale score (OR 1.90 and 95% CI 1.46 - 2.48), and higher risk of long-term mortality (HR 1.30 and 95% CI 1.03 - 1.64). Conclusion. From this study, we documented that WML was associated with development and increased volume IVH in acute ICH patients. WML would be considered in diagnosis and management of ICH patients with IVH.

Age over 80 years is not associated with increased hemorrhagic transformation after stroke thrombolysis

Thrombolysis trials have recruited few patients aged ⩾80years, which has led to uncertainty about the likely risk-to-benefit profile in the elderly. Leukoaraiosis (LA) has been associated with hemorrhagic transformation (HT) and increases with advanced age. We tested whether there were any independent associations between age, LA and HT. Consecutive patients treated with intravenous (IV) tissue plasminogen activator (tPA) were identified from a prospective database. LA on baseline CT scans was assessed by two independent raters using the modified Van Swieten Score (mVSS) (maximum score 8, severe >4). HT was assessed on routine 24hour to 48hour CT /MRI scans using the European Cooperative Acute Stroke Study criteria for hemorrhagic infarct (HI) or parenchymal hematoma (PH) and judged symptomatic by the treating neurologist as per Safe Implementation of Thrombolysis in Stroke criteria. There were 206 patients treated with IV tPA (mean age: 71.0years; range: 24–92years), of whom 65/206 (32%) were aged ⩾80years. Overall, HT occurred in 41/206 patients (20%), HI in 31, PH1 in four (one symptomatic) and PH2 in six (three symptomatic). Age was not associated with HT (any HT: odds ratio [OR]=1.01; 95% confidence interval [CI]=0.5–2.08; p=0.99; PH: OR=0.53; 95% CI=0.12–2.3; p=0.51). There was one patient with PH1 and one patient with PH2 in 65 patients ⩾80years, both asymptomatic. LA was present in 112/208 (54%), and severe in 16.5%. LA increased with age (p<0.001) but was not associated with PH (any LA: OR=0.83; 95% CI=0.25–2.8; p=0.99; severe LA: OR=0.54, 95% CI=0.09–3.5; p=0.99). Age ⩾80years or LA did not increase the risk of HT (including PH) after thrombolysis, although LA increased with age. Neither factor should exclude otherwise eligible patients from tPA treatment.

Gout and kidney during XVII and XIX centuries

The authors briefly describe the history of gout, mainly focusing their attention on the renal involvement. They report some works and theories on gout of great ancient physicians, such as Paracelsus, Sydenham, Boerhaave, Van Swieten and Morgagni.

Characterization of Prefibrillar Tau Oligomers in Vitro and in Alzheimer Disease

Neurofibrillary tangles, composed of insoluble aggregates of the microtubule-associated protein Tau, are a pathological hallmark of Alzheimer disease (AD) and other tauopathies. However, recent evidence indicates that neuronal dysfunction precedes the formation of these insoluble fibrillar deposits, suggesting that earlier prefibrillar Tau aggregates may be neurotoxic. To determine the composition of these aggregates, we have employed a photochemical cross-linking technique to examine intermolecular interactions of full-length Tau in vitro. Using this method, we demonstrate that dimerization is an early event in the Tau aggregation process and that these dimers self-associate to form larger oligomeric aggregates. Moreover, using these stabilized Tau aggregates as immunogens, we generated a monoclonal antibody that selectively recognizes Tau dimers and higher order oligomeric aggregates but shows little reactivity to Tau filaments in vitro. Immunostaining indicates that these dimers/oligomers are markedly elevated in AD, appearing in early pathological inclusions such as neuropil threads and pretangle neurons as well as colocalizing with other early markers of Tau pathogenesis. Taken as a whole, the work presented herein demonstrates the existence of alternative Tau aggregates that precede formation of fibrillar Tau pathologies and raises the possibility that these hierarchical oligomeric forms of Tau may contribute to neurodegeneration.

Mutant HFE H63D Protein Is Associated with Prolonged Endoplasmic Reticulum Stress and Increased Neuronal Vulnerability

A specific polymorphism in the hemochromatosis (HFE) gene, H63D, is over-represented in neurodegenerative disorders such as amyotrophic lateral sclerosis and Alzheimer disease. Mutations of HFE are best known as being associated with cellular iron overload, but the mechanism by which HFE H63D might increase the risk of neuron degeneration is unclear. Here, using an inducible expression cell model developed from a human neuronal cell line SH-SY5Y, we reported that the presence of the HFE H63D protein activated the unfolded protein response (UPR). This response was followed by a persistent endoplasmic reticulum (ER) stress, as the signals of UPR sensors attenuated and followed by up-regulation of caspase-3 cleavage and activity. Our in vitro findings were recapitulated in a transgenic mouse model carrying Hfe H67D, the mouse equivalent of the human H63D mutation. In this model, UPR activation was detected in the lumbar spinal cord at 6 months then declined at 12 months in association with increased caspase-3 cleavage. Moreover, upon the prolonged ER stress, the number of cells expressing HFE H63D in early apoptosis was increased moderately. Cell proliferation was decreased without increased cell death. Additionally, despite increased iron level in cells carrying HFE H63D, it appeared that ER stress was not responsive to the change of cellular iron status. Overall, our studies indicate that the HFE H63D mutant protein is associated with prolonged ER stress and chronically increased neuronal vulnerability.

Schizophrenia-Like Alcoholic Dementia or Dementia Praecox

Back to table of contents Previous article Next article LettersFull AccessSchizophrenia-Like Alcoholic Dementia or Dementia PraecoxLuís Fonseca, M.D., and Joaquim Duarte, M.D.Luís FonsecaSearch for more papers by this author, M.D., and Joaquim DuarteSearch for more papers by this author, M.D.Published Online:1 Jan 2011AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail To the Editor: A clear distinction between schizophrenia and some clusters of dementia is sometimes difficult to establish in clinical practice.Case ReportA 38-year-old man with a history of alcohol dependence (alcohol consumption started at the age of 6 years) was admitted to our unit for generalized tremor; sweating; agitation; auditory, visual, and kinesthetic hallucinations; thought-broadcasting; and persecutory delusion. He was medicated with diazepam, 20 mg, and thiamine, 200 mg. Agitation and the vegetative symptoms gradually subsided within 48 hours. Lab work showed no significant changes, and EEG and ECG were normal. A brain MRI showed generalized cortical atrophy. Seven days after the admission, we prescribed olanzapine 10 mg because the psychotic symptoms had persisted. There was a gradual improvement, and, 26 days after admission, the patient was discharged home asymptomatic. Two months later he was admitted to a medical unit for a grand mal seizure after a 48-hour period of abstinence. After medical stabilization, psychiatric evaluation elicited the same previous psychotic symptoms. Olanzapine, 10 mg, was again prescribed, with symptomatic improvement. A neuropsychological study, requested during follow-up because of his cognitive impairment, revealed a severe frontotemporal cognitive defect.During the year before the admission, the patient presented with auditory and kinesthetic hallucinations, thought-broadcasting, and persecutory delusions. Also, he had continued drinking large amounts of alcohol daily during this period.DiscussionAlcohol has not been identified as a possible etiological factor for schizophrenia. Also, the high comorbidity between alcohol abuse and schizophrenia remains obscure.1 Alcoholic dementia is controversial. Long-term alcohol abuse appears to elicit its onset later in life through a mechanism of continuous brain insult.2,3Beginning his alcohol consumption at the age of 6, cognitive deterioration, and generalized cortical atrophy shown in the brain MRI suggest an alcoholic dementia.4 However, maintenance of typical positive schizophrenia symptoms beyond delirium tremens as with alcohol abstinence fulfills DSM-IV diagnostic criteria for schizophrenia. Also, the same neuropsychological deficits encountered in our patient are described in early-onset frontotemporal dementia presenting as schizophrenia-like psychosis in young people.5The difficulty in clearly distinguishing schizophrenia from some dementias may be because, as Kraepelin stated in the 19th century, schizophrenia is itself a form of early dementia. His concept of dementia praecox6,7 is supported nowadays by the knowledge acquired from several neuropsychological and neuroimaging tests that a progressive cognitive deterioration occurs in schizophrenic patients. Our case also supports this phenomenological concept of dementia praecox, independently of the associated etiological mechanisms.Psychiatry and Mental Health Department, Braga Hospital, Portugal1. Green AI , Drake RE , Brunette MF, et al.: Schizophrenia and co-occurring substance use disorder. Am J Psychiatry 2007; 164:402–408Crossref, Medline, Google Scholar2. Ruitenberg A , van Swieten JC , Witteman JC, et al.: Alcohol consumption and the risk of dementia: the Rotterdam study. Lancet 2002; 359:281–286Crossref, Medline, Google Scholar3. Kosten T , Ziedonis D: Substance abuse and schizophrenia: editors' introduction. Schizophr Bull 1997; 23:181–186Crossref, Medline, Google Scholar4. Moriyama Y , Mimura M , Kato M, et al.: Primary alcoholic dementia and alcohol-related dementia. Psychogeriatrics 2006; 6:114–118Crossref, Google Scholar5. Velakoulis D , Walterfang M , Mocellin R: Frontotemporal dementia presenting as schizophrenia-like psychosis in young people: clinicopathological series and review of cases. The British Journal of Psychiatry (2009) 194:298–305Crossref, Medline, Google Scholar6. Emil Kraepelin: A Demência Precoce: 1a parte. Climepsi Editores, 2004Google Scholar7. Emil Kraepelin: A Demência Precoce: 2a parte, parafrenias. Climepsi Editores, 2004Google Scholar FiguresReferencesCited byDetailsCited ByNone Volume 23Issue 1 Winter 2011Pages E11-E11 Metrics PDF download History Published online 1 January 2011 Published in print 1 January 2011

Accelerated Human Mutant Tau Aggregation by Knocking Out Murine Tau in a Transgenic Mouse Model

Many models of human tauopathies have been generated in mice by expression of a human mutant tau with maintained expression of mouse endogenous tau. Because murine tau might interfere with the toxic effects of human mutant tau, we generated a model in which a pathogenic human tau protein is expressed in the absence of wild-type tau protein, with the aim of facilitating the study of the pathogenic role of the mutant tau and to reproduce more faithfully a human tauopathy. The Tg30 line is a tau transgenic mouse model overexpressing human 1N4R double-mutant tau (P301S and G272V) that develops Alzheimer's disease-like neurofibrillary tangles in an age-dependent manner. By crossing Tg30 mice with mice invalidated for their endogenous tau gene, we obtained Tg30xtau(-/-) mice that express only exogenous human double-mutant 1N4R tau. Although Tg30xtau(-/-) mice express less tau protein compared with Tg30, they exhibit signs of decreased survival, increased proportion of sarkosyl-insoluble tau in the brain and in the spinal cord, increased number of Gallyas-positive neurofibrillary tangles in the hippocampus, increased number of inclusions in the spinal cord, and a more severe motor phenotype. Deletion of murine tau accelerated tau aggregation during aging of this mutant tau transgenic model, suggesting that murine tau could interfere with the development of tau pathology in transgenic models of human tauopathies.

Leukoaraiosis Predicts Poor Outcome after Spontaneous Supratentorial Intracerebral Hemorrhage

Background and Aims: Leukoaraiosis (LA) is associated with aging and vascular risk factors, and is a risk factor of intracerebral hemorrhage (ICH) after treatment with warfarin or thrombolytic treatment for ischemic stroke. In this study, we sought to examine whether LA is a predictor of outcome after spontaneous ICH. Methods: We retrospectively analyzed 238 consecutive patients with spontaneous supratentorial ICH identified by a database search. Patients were divided into two groups according to neurological outcome at 90 days: patients with good outcomes (Glasgow Outcome Scale ≧4) and patients with poor outcomes. Demographic features, ICH characteristics, and LA severity as assessed by van Swieten score on brain CT were compared between the two groups. Results: Overall, 105 (44.1%) of the patients analyzed had poor outcomes. In univariate analysis, LA severity, ICH volume on initial brain CT, initial Glasgow Coma Scale (GCS), presence of intraventricular hemorrhage (IVH), old age, surgical treatment, and higher admission serum glucose level were associated with poor outcome. Multiple logistic regression analysis showed that severity of LA, initial GCS score, hematoma volume, presence of IVH, and surgical treatment were independent predictors of poor outcome. Conclusion: LA is an independent predictor of poor neurological outcome in patients with spontaneous supratentorial ICH.

Playing with Art: Musical Arrangements as Educational Tools in van Swieten's Vienna

Art played a significant part in the educational ideal promoted by German intellectuals in the late eighteenth century. Gottfried van Swieten, President of the Court Commission for Education in Vienna and librettist for The Creation, was instrumental in developing and promoting the role of art in the moral education of the individual. His encouragement of active engagement with art sheds new light on the common practice of arranging musical "classics"—in particular large-scale vocal works—for smaller instrumental forces around 1800. Van Swieten's writings suggest that such arrangements may be understood not merely as entertaining trifles but as the product of the sociopolitical mores of the Enlightenment. Inviting the direct, interactive experience of art, the arrangement of Joseph Haydn's Creation for string quintet was particularly suited to the moral and social education of the individual. Grounded at least in part in archaic compositional practices, it demonstrated an artwork's adaptability to different circumstances of performance and to the different levels of education of its performers. Moreover, the act of playing the arrangement, one to a part, allowed for the honing of an individual's inner sociable sentiment through collaboration with fellow performers.

Austrian pharmacy in the 18 and 19th century.

This overview reflects the extensive changes in the health care system which had significant effects on the apothecary’s profession and education. In the 18th century Maria Theresia assigned Gerard van Swieten to modernize the medical curriculum and to work out reforms for health care. The resulting sanitary bill released in 1770 and amended in 1773 became effective for the whole empire and influenced greatly the apothecary’s profession. The Viennese Medical Faculty continued to be the supervisory body for the apothecaries, a situation which prolonged the conflicts between the faculty and the apothecaries. The financial and social distress prevalent in the 19th century also affected the apothecary business and led to a crisis of the profession. Furthermore, the apothecaries’ missing influence over the sanitary authorities delayed the release of a badly needed new apothecary bill until 1906. The introduction of a specific pharmaceutical curriculum at the university in 1853 was a great step forward to improve the pharmaceutical education. Nevertheless, the secondary school exam was not compulsory for the studies until 1920 and, therefore, the graduates were not on a par with other university graduates before that date. Women, except nuns, were not allowed to work as pharmacists until 1900.

Rapamycin Rescues TDP-43 Mislocalization and the Associated Low Molecular Mass Neurofilament Instability

TDP-43 is a nuclear protein involved in exon skipping and alternative splicing. Recently, TDP-43 has been identified as the pathological signature protein in frontotemporal lobar degeneration with ubiquitin-positive inclusions and in amyotrophic lateral sclerosis. In addition, TDP-43-positive inclusions are present in Parkinson disease, dementia with Lewy bodies, and 30% of Alzheimer disease cases. Pathological TDP-43 is redistributed from the nucleus to the cytoplasm, where it accumulates. An approximately 25-kDa C-terminal fragment of TDP-43 accumulates in affected brain regions, suggesting that it may be involved in the disease pathogenesis. Here, we show that overexpression of the 25-kDa C-terminal fragment is sufficient to cause the mislocalization and cytoplasmic accumulation of endogenous full-length TDP-43 in two different cell lines, thus recapitulating a key biochemical characteristic of TDP-43 proteinopathies. We also found that TDP-43 mislocalization is associated with a reduction in the low molecular mass neurofilament mRNA levels. Notably, we show that the autophagic system plays a role in TDP-43 metabolism. Specifically, we found that autophagy inhibition increases the accumulation of the C-terminal fragments of TDP-43, whereas inhibition of mTOR, a key protein kinase involved in autophagy regulation, reduces the 25-kDa C-terminal fragment accumulation and restores TDP-43 localization. Our results suggest that autophagy induction may be a valid therapeutic target for TDP-43 proteinopathies.

Effect of Pin1 or Microtubule Binding on Dephosphorylation of FTDP-17 Mutant Tau

Neurodegenerative tauopathies, including Alzheimer disease, are characterized by abnormal hyperphosphorylation of the microtubule-associated protein Tau. One group of tauopathies, known as frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17), is directly associated with mutations of the gene tau. However, it is unknown why mutant Tau is highly phosphorylated in the patient brain. In contrast to in vivo high phosphorylation, FTDP-17 Tau is phosphorylated less than wild-type Tau in vitro. Because phosphorylation is a balance between kinase and phosphatase activities, we investigated dephosphorylation of mutant Tau proteins, P301L and R406W. Tau phosphorylated by Cdk5-p25 was dephosphorylated by protein phosphatases in rat brain extracts. Compared with wild-type Tau, R406W was dephosphorylated faster and P301L slower. The two-dimensional phosphopeptide map analysis suggested that faster dephosphorylation of R406W was due to a lack of phosphorylation at Ser-404, which is relatively resistant to dephosphorylation. We studied the effect of the peptidyl-prolyl isomerase Pin1 or microtubule binding on dephosphorylation of wild-type Tau, P301L, and R406W in vitro. Pin1 catalyzes the cis/trans isomerization of phospho-Ser/Thr-Pro sequences in a subset of proteins. Dephosphorylation of wild-type Tau was reduced in brain extracts of Pin1-knockout mice, and this reduction was not observed with P301L and R406W. On the other hand, binding to microtubules almost abolished dephosphorylation of wild-type and mutant Tau proteins. These results demonstrate that mutation of Tau and its association with microtubules may change the conformation of Tau, thereby suppressing dephosphorylation and potentially contributing to the etiology of tauopathies.

Headaches in antiquity and during the early scientific era

This paper presents the evolution of ideas on headache symptoms from antiquity through the 19th century. A thorough study of texts, medical books and reports along with a review of the available literature in PubMed was undertaken: observations on headaches date back nearly 4,000 years to the ritual texts of Mesopotamia. Nicolaes Tulp, Thomas Willis and Gerhard van Swieten also made important contributions on various forms of headaches in the 17th and 18th centuries. Edward Liveing and William Gowers made the major contributions to the field in the late 19th century. Overall, observations on headaches span a timeline of nearly 9,000 years. The work of the physicians during the 18th and 19th century, however, set the basis for scientific research.

Proepithelin Regulates Prostate Cancer Cell Biology by Promoting Cell Growth, Migration, and Anchorage-Independent Growth

The growth factor proepithelin has recently emerged as an important regulator of transformation in several physiological and pathological systems. In this study, we determined the biological roles of proepithelin in prostate cancer cells using purified human recombinant proepithelin as well as proepithelin-depletion strategies. Proepithelin promoted the migration of androgen-dependent and -independent human prostate cancer cells; androgen-independent DU145 cells were the more responsive. In these cells, proepithelin additionally stimulated wound closure, invasion, and promotion of cell growth in vitro. These effects required the activation of both the Akt and mitogen-activated protein kinase pathways. We have analyzed proepithelin expression levels in different available prostate cancer microarray studies using the Oncomine database and found a statistically significant increase in proepithelin mRNA expression levels in prostate cancers compared with nonneoplastic controls. Notably, depletion of endogenous proepithelin by siRNA and antisense strategies impaired the ability of DU145 cells to grow and migrate after serum withdrawal and inhibited anchorage-independent growth. Our results provide the first evidence for a role of proepithelin in stimulating the migration, invasion, proliferation, and anchorage-independent growth of prostate cancer cells. This study supports the hypothesis that proepithelin may play a critical role as an autocrine growth factor in the establishment and initial progression of prostate cancer. Furthermore, proepithelin may prove to be a useful clinical marker for the diagnosis of prostate tumors.

Importance of Leukoaraiosis on CT for Tissue Plasminogen Activator Decision Making: Evaluation of the NINDS rt-PA Stroke Study

Background: Leukoaraiosis is associated with microhemorrhages on T₂*-weighted magnetic resonance imaging of the brain. Such hemorrhages have been postulated to be responsible for symptomatic intracerebral hemorrhage (ICH) after thrombolytic treatment. We examined the relationship between small-vessel ischemic disease and symptomatic ICH within the NINDS rt-PA Stroke Study. Methods: Baseline CT scans from the NINDS rt-PA Stroke Study were re-evaluated retrospectively by blinded expert CT readers using the van Swieten Score (vSS) for leukoaraiosis. The scale examined the severity of white-matter changes on 3 serial CT slices and graded separately for the 2 distinct regionsanterior and posterior to the central sulcus: 0 = no lesion, 1 = partlyinvolving the white matter, and 2 = extending up to the cortex. Results: 603 CT scans were interpreted. The risk of symptomatic ICH increased with higher vSS in both the placebo and treatment groups. The absolute risk of symptomatic hemorrhage was 7.9% in the rt-PA-treated cohort among patients with severe white-matter disease (vSS = 3–4) versus 2.9% receiving placebo. Among severe leukoaraiosis patients (vSS = 3–4), no differential treatment effect was seen with rt-PA patients achieving better outcomes than placebo, modified Rankin score 0–1 in 31.6% of rt-PA-treated versus 14.7% of placebo-treated patients. Conclusion: The results from the present study do not support the concept that leukoaraiosis present on baseline noncontrast CT scanning is critical to thrombolysis decision making in the first 3 h from symptom onset. No clear leukoaraiosis threshold was identified below which no benefit or harm could be seen from intravenous rt-PA therapy.

DJ-1 Decreases Bax Expression through Repressing p53 Transcriptional Activity

DJ-1, originally identified as an oncogene product, is a protein with various functions in cellular transformation, oxidative stress response, and transcriptional regulation. Although previous studies suggest that DJ-1 is cytoprotective, the mechanism by which DJ-1 exerts its survival functions remains largely unknown. Here we show that DJ-1 exerts its cytoprotection through inhibiting p53-Bax-caspase pathway. DJ-1 interacts with p53 in vitro and in vivo. Overexpression of DJ-1 decreases the expression of Bax and inhibits caspase activation, whereas knockdown of DJ-1 increases Bax protein levels and accelerates caspase-3 activation and cell death induced by UV exposure. Our data provide evidence that the protective effects of DJ-1 on apoptosis are associated with its ability of decreasing Bax level through inhibiting p53 transcriptional activity.

Gerardi van Swieten: descriptions of episodic cluster headache

In 1745, Gerhard van Swieten published, in Latin, a five volume commentary on the writings of Boerhaave1 that influenced medical practice throughout Europe. It contains the following account, considered by...

Fibrillogenic Nuclei Composed of P301L Mutant Tau Induce Elongation of P301L Tau but Not Wild-type Tau

Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), an autosomal, dominantly inherited neurodegenerative disorder caused by tau gene mutations, is neuropathologically characterized by intraneuronal filamentous inclusions of hyperphosphorylated tau protein. Biochemical and immunocytochemical analyses have shown that only mutant tau is deposited in patients harboring P301L missense mutation, whereas both wild-type and mutant tau are deposited in patients harboring R406W mutation (Miyasaka, T., Morishima-Kawashima, M., Ravid, R., Kamphorst, W., Nagashima, K., and Ihara, Y. (2001) J. Neuropathol. Exp. Neurol. 60, 872- 884 and Miyasaka, T., Morishima-Kawashima, M., Ravid, R., Heutink, P., van Swieten, J. C., Nagashima, K., and Ihara, Y. (2001) Am. J. Pathol. 158, 373-379). Here we have tested the nucleation ability of monomeric tau and the seeding ability of fibrillogenic nuclei obtained from bacterially expressed human tau. P301L mutant tau showed a higher nucleation ability than wild-type tau, whereas R406W mutant tau shows similar ability to wild-type tau. Surprisingly, fibrillogenic nuclei composed of P301L mutant tau enhanced the assembly of P301L mutant tau into filaments but did not promote filament formation from wild-type tau. In contrast, nuclei composed of R406W mutant tau supported filament formation from both wild-type tau and R406W mutant tau, as did nuclei composed of wild-type tau. Proteolytic analyses indicated that the substructure of nuclei composed of P301L mutant tau was different from that of nuclei composed of wild-type or R406W mutant tau. Thus, the interaction between fibrillogenic nuclei and monomeric protein appears to play an important role in the mechanism of tau filament assembly.

N-Azidoacetylmannosamine-mediated chemical tagging of gangliosides

Peracetylated N-alpha-azidoacetylmannosamine (Ac(4)ManNAz) is metabolized by cells to CMP-azidosialic acid. It has been demonstrated previously that in this way azidosialic acid-containing glycoproteins are formed that can be labeled on the cell surface by a modified Staudinger ligation. Here, we first demonstrate that the same procedure also results in the formation of azidosialic acid-containing gangliosides. Deoxymannojirimycin, an inhibitor of N-glycan processing in proteins, decreases the total cell surface labeling in Jurkat cells by approximately 25%. Inhibition of ganglioside biosynthesis with N-[5-(adamantan-1-yl-methoxy)-pentyl]1-deoxynojirimycin reduces cell surface labeling by approximately 75%. In conclusion, exposure of cells to Ac(4)ManNAz allows in vivo chemical tagging of gangliosides.

Structural Determinants of the C-terminal Helix-Kink-Helix Motif Essential for Protein Stability and Survival Promoting Activity of DJ-1

Mutations in the PARK7 gene encoding DJ-1 cause autosomal recessive Parkinson disease. The most deleterious point mutation is the L166P substitution, which resides in a structure motif comprising two alpha-helices (G and H) separated by a kink. Here we subjected the C-terminal helix-kink-helix motif to systematic site-directed mutagenesis, introducing helix-incompatible proline residues as well as conservative substitutions into the helical interface. Furthermore, we generated deletion mutants lacking the H-helix, the kink, and the entire C terminus. When transfected into neural and nonneural cell lines, steady-state levels of G-helix breaking and kink deletion mutants were dramatically lower than wild-type DJ-1. The effects of H-helix breakers were comparably smaller, and the non-helix breaking mutants only slightly destabilized DJ-1. The decreased steady-state levels were due to accelerated protein degradation involving in part the proteasome. G-helix breaking DJ-1 mutations abolished dimer formation. These structural perturbations had functional consequences on the cytoprotective activities of DJ-1. The destabilizing mutations conferred reduced cytoprotection against H(2)O(2) in transiently retransfected DJ-1 knock-out mouse embryonic fibroblasts. The loss of survival promoting activity of the DJ-1 mutants with destabilizing C-terminal mutations correlated with impaired anti-apoptotic signaling. We found that wild-type, but not mutant DJ-1 facilitated the Akt pathway and simultaneously blocked the apoptosis signal-regulating kinase 1, with which DJ-1 interacted in a redox-dependent manner. Thus, the G-helix and kink are critical determinants of the C-terminal helix-kink-helix motif, which is absolutely required for stability and the regulation of survival-promoting redox signaling of the Parkinson disease-associated protein DJ-1.