The molecular basis of frontotemporal dementia

Frontotemporal dementia (FTD) is a clinical syndrome with a heterogeneous molecular basis. Familial FTD has been linked to mutations in several genes, including those encoding the microtubule-associated protein tau (MAPT), progranulin (GRN), valosin-containing protein (VCP) and charged multivescicular body protein 2B (CHMP2B). The associated neuropathology is characterised by selective degeneration of the frontal and temporal lobes (frontotemporal lobar degeneration, FTLD), usually with the presence of abnormal intracellular protein accumulations. The current classification of FTLD neuropathology is based on the identity of the predominant protein abnormality, in the belief that this most closely reflects the underlying pathogenic process. Major subgroups include those characterised by the pathological tau, TDP-43, intermediate filaments and a group with cellular inclusions composed of an unidentified ubiquitinated protein. This review will focus on the current understanding of the molecular basis of each of the major FTLD subtypes. It is anticipated that this knowledge will provide the basis of future advances in the diagnosis and treatment of FT

Recent biomarker approaches in the diagnosis of frontotemporal lobar degeneration/Neurochemische Ansätze in der Diagnose der Frontotemporalen Lobärdegeneration

Frontotemporal lobar degeneration (FTLD) is a heterogeneous group of syndromes with different symptoms. Frontotemporal lobar degeneration is mostly used as a clinical umbrella term for different diseases. In some clinical subtypes of the FTLD spectrum, a close correlation with underlying pathology can be found. Neuroimaging techniques, such as magnetic resonance imaging and position emission tomography help to detect neuroanatomical lesions and therefore obtain relevance for in vivo prediction of neurodegeneration. However, there is still a lack of neurochemical biomarkers helping to differentiate between underlying histopathologies. The following review gives an overview about present neurochemical biomarker studies and perspective approaches in the diagnosis of FTL

Transgenic mice expressing mutant forms VCP/p97 recapitulate the full spectrum of IBMPFD including degeneration in muscle, brain and bone

Inclusion body myopathy associated with Paget's disease of bone and frontotemporal dementia (IBMPFD) is a dominantly inherited degenerative disorder caused by mutations in the valosin-containing protein (VCP) gene. VCP (p97 in mouse, TER94 in Drosophila melanogaster and CDC48 in Saccharomyces cerevisiae) is a highly conserved AAA+-ATPase that regulates a wide array of cellular processes. The mechanism of IBMPFD pathogenesis is unknown. Towards elucidating the pathogenic mechanism we have developed and characterized transgenic mice with ubiquitous expression of wild-type and disease-causing versions of human VCP/p97. Here, we report that mice expressing VCP/p97 harboring the mutations R155H or A232E develop pathology that is limited to muscle, brain and bone, recapitulating the spectrum of disease in humans with IBMPFD. The mice exhibit progressive muscle weakness and pathological examination of muscle shows classic characteristics of inclusion body myopathy including rimmed vacuoles and TDP-43 pathology. The mice exhibit abnormalities in behavioral testing and pathological examination of the brain shows widespread TDP-43 pathology. Furthermore, radiological examination of the skeleton reveals that mutant mice develop severe osteopenia accompanied by focal lytic and sclerotic lesions in vertebrae and femur. In vitro studies indicate that mutant VCP causes inappropriate activation of the NF-κB signaling cascade, which could contribute to the mechanism of pathogenesis in multiple tissues including muscle, bone and brai

Forschungsbericht zur Ist-Stands-Analyse im BMBF Verbundvorhaben ChemNet

Der vorliegende Forschungsbericht ist das erste Teilergebnis der wissenschaftlichen Begleitforschung im vom BMBF geförderten Projekt ChemNet. Mit ChemNet soll eine Online-Plattform entwickelt werden die für die Erstausbildung, die berufliche Weiterbildung als auch für die Aufstiegsqualifizierung im Chemiesektor genutzt werden kann – dies sogar im europäischen Kontext. Der Forschungsbericht stellt die Ergebnisse der Ist-Stand-Analyse von u.a. Ausbildungsverhältnissen, Computernutzung und Computerbezogenen Einstellungen von Auszubildenden, Teilnehmern der Aufstiegsqualifizierung, Berufsschullehrern, Ausbildern in der überbetrieblichen Ausbildung sowie betrieblichen Ausbildern dar. Dabei wurden etablierte Instrumente aus dem Inventar zur Computerbildung (INCOBI-R) verwendet. Deutlich konnten dabei die Unterschiede in der Nutzung von Informations- und Kommunikationstechnologien zwischen den Gruppen von Lehrenden und Lernenden herausgearbeitet werden, die sich auch in den Computerbezogenen Einstellungen wiederspiegeln.:Abbildungsverzeichnis IV Tabellenverzeichnis IX 1 Einführung und Ausgangslage 1 2 Ziele und Design der Untersuchung 1 2.1 Problemhintergrund 1 2.2 Zielstellung 2 2.3 Zielgruppen 3 2.4 Theoretischer Hintergrund und Forschungsstand 3 2.4.1 Mediennutzung 3 2.4.2 Lernortkooperation 5 2.5 Forschungsdesign 8 2.5.1 Grundgesamtheit und Zahl der Rückläufe 9 2.5.2 Fragebogenkonstruktion 10 3 Präsentation der Daten 11 3.1 Soziodemografische Daten 12 3.1.1 Daten der Auszubildenden 12 3.1.2 Daten der Berufsschullehrer 15 3.1.3 Daten der Ausbilder der überbetrieblichen Bildungsstätte 17 3.1.4 Daten der betrieblichen Ausbilder 18 3.1.5 Daten der Teilnehmer der Aufstiegsqualifizierung zum Industriemeister 20 3.2 Berufliche Situation im Betrieb 22 3.2.1 Auszubildende 22 3.2.2 Betriebliche Ausbilder 27 3.2.3 Teilnehmer der Aufstiegsqualifizierung 29 3.3 Ausbildungssituation an ÜBS und Berufsschule 33 3.4 Einschätzung des Ausbildungsstandes 34 3.4.1 Selbsteinschätzung der Auszubildenden 34 3.4.2 Fremdeinschätzung durch Berufsschullehrer und (über-)betriebliche Ausbilder 36 3.4.3 Selbsteinschätzung der Teilnehmer der Aufstiegsqualifizierung 43 3.5 Kommunikation 46 3.5.1 Fachlicher Austausch 46 3.5.2 Kommunikationswege/-mittel 49 3.5.3 Einschätzung der Kommunikation 58 3.6 Mediennutzung 66 3.6.1 Computernutzung 66 3.6.2 Internetnutzung 79 3.6.3 Sicherheit im Umgang mit Computern und Computeranwendungen 91 3.6.4 Computerbezogene Einstellungen 97 4 Weiterführende Analyse der Daten 107 4.1 Mittelwertdarstellungen von Alter, Ausbildertätigkeit und Computernutzung in Jahren 107 4.2 Vergleich der Gruppenvarianzen – einfaktorielle ANOVA 108 5 Zusammenfassung und weitere Arbeitsschritte 110 5.1 Zusammenfassung 110 5.2 Weitere Arbeitsschritte 112 6 Quellen 11

Autophagy generates citrullinated peptides in human synoviocytes: a possible trigger for anti-citrullinated peptide antibodies

OBJECTIVES: Autophagy may represent a functional processing event that creates a substrate for autoreactivity. In particular, autophagy may play a role in the pathogenesis of RA, since autophagy is a key cellular event involved in the generation of citrullinated peptides, with consequent breakage of tolerance. Thus, in RA, autophagy may be the common feature in several situations (including smoking, joint injury and infection) that may drive the adaptive responses to citrullinated self-proteins. The aim of this study was the analysis, in vitro, of the role of autophagy in the generation of citrullinated peptides and, in vivo, of the relationship between autophagy and the production of anti-CCP antibodies (Abs). METHODS: For autophagy induction, fibroblast-like synoviocytes, primary fibroblasts and monocytes were stimulated with tunicamycin or rapamycin. Peptidyl arginine deiminase activity was tested by enzyme-linked immunosorbent assay, and protein citrullination was evaluated by western blotting. The main citrullinated RA candidate antigens, vimentin, α-enolase and filaggrin, were demonstrated by immunoprecipitation. The relationship between autophagy and anti-CCP Abs was analysed in 30 early-active RA patients. RESULTS: Our results demonstrated in vitro a role for autophagy in the citrullination process. Cells treated with tunicamycin or rapamycin showed peptidyl arginine deiminase 4 activation, with consequent protein citrullination. Immunoblotting and immunoprecipitation experiments, using specific Abs, identified the main citrullinated proteins: vimentin, α-enolase and filaggrin. In vivo, a significant association between levels of autophagy and anti-CCP Abs was observed in treatment-naïve early-active RA patients. CONCLUSION: These findings support the view that the processing of proteins in autophagy generates citrullinated peptides recognized by the immune system in RA

A new subtype of frontotemporal lobar degeneration with FUS pathology

Frontotemporal dementia (FTD) is a clinical syndrome with a heterogeneous molecular basis. The neuropathology associated with most FTD is characterized by abnormal cellular aggregates of either transactive response DNA-binding protein with Mr 43 kDa (TDP-43) or tau protein. However, we recently described a subgroup of FTD patients, representing around 10%, with an unusual clinical phenotype and pathology characterized by frontotemporal lobar degeneration with neuronal inclusions composed of an unidentified ubiquitinated protein (atypical FTLD-U; aFTLD-U). All cases were sporadic and had early-onset FTD with severe progressive behavioural and personality changes in the absence of aphasia or significant motor features. Mutations in the fused in sarcoma (FUS) gene have recently been identified as a cause of familial amyotrophic lateral sclerosis, with these cases reported to have abnormal cellular accumulations of FUS protein. Because of the recognized clinical, genetic and pathological overlap between FTD and amyotrophic lateral sclerosis, we investigated whether FUS might also be the pathological protein in aFTLD-U. In all our aFTLD-U cases (n = 15), FUS immunohistochemistry labelled all the neuronal inclusions and also demonstrated previously unrecognized glial pathology. Immunoblot analysis of protein extracted from post-mortem aFTLD-U brain tissue demonstrated increased levels of insoluble FUS. No mutations in the FUS gene were identified in any of our patients. These findings suggest that FUS is the pathological protein in a significant subgroup of sporadic FTD and reinforce the concept that FTD and amyotrophic lateral sclerosis are closely related condition

Neuropathological background of phenotypical variability in frontotemporal dementia

Frontotemporal lobar degeneration (FTLD) is the umbrella term encompassing a heterogeneous group of pathological disorders. With recent discoveries, the FTLDs have been show to classify nicely into three main groups based on the major protein deposited in the brain: FTLD-tau, FTLD-TDP and FTLD-FUS. These pathological groups, and their specific pathologies, underlie a number of well-defined clinical syndromes, including three frontotemporal dementia (FTD) variants [behavioral variant frontotemporal dementia (bvFTD), progressive non-fluent aphasia, and semantic dementia (SD)], progressive supranuclear palsy syndrome (PSPS) and corticobasal syndrome (CBS). Understanding the neuropathological background of the phenotypic variability in FTD, PSPS and CBS requires large clinicopathological studies. We review current knowledge on the relationship between the FTLD pathologies and clinical syndromes, and pool data from a number of large clinicopathological studies that collectively provide data on 544 cases. Strong relationships were identified as follows: FTD with motor neuron disease and FTLD-TDP; SD and FTLD-TDP; PSPS and FTLD-tau; and CBS and FTLD-tau. However, the relationship between some of these clinical diagnoses and specific pathologies is not so clear cut. In addition, the clinical diagnosis of bvFTD does not have a strong relationship to any FTLD subtype or specific pathology and therefore remains a diagnostic challenge. Some evidence suggests improved clinicopathological association of bvFTD by further refining clinical characteristics. Unlike FTLD-tau and FTLD-TDP, FTLD-FUS has been less well characterized, with only 69 cases reported. However, there appears to be some associations between clinical phenotypes and FTLD-FUS pathologies. Clinical diagnosis is therefore promising in predicting molecular pathology

Phosphorylation of S409/410 of TDP-43 is a consistent feature in all sporadic and familial forms of TDP-43 proteinopathies

Accumulation of hyperphosphorylated, ubiquitinated and N-terminally truncated TAR DNA-binding protein (TDP-43) is the pathological hallmark lesion in most familial and sporadic forms of FTLD-U and ALS, which can be subsumed as TDP-43 proteinopathies. In order to get more insight into the role of abnormal phosphorylation in the disease process, the identification of specific phosphorylation sites and the generation of phosphorylation-specific antibodies are mandatory. Here, we developed and characterized novel rat monoclonal antibodies (1D3 and 7A9) raised against phosphorylated S409/410 of TDP-43. These antibodies were used to study the presence of S409/410 phosphorylation by immunohistochemistry and biochemical analysis in a large series of 64 FTLD-U cases with or without motor neuron disease including familial cases with mutations in progranulin (n=5), valosin-containing protein (n=4) and linkage to chromosome 9p (n=4), 18 ALS cases as well as other neurodegenerative diseases with concomitant TDP-43 pathology (n=5). Our data demonstrate that phosphorylation of S409/410 of TDP-43 is a highly consistent feature in pathologic inclusions in the whole spectrum of sporadic and familial forms of TDP-43 proteinopathies. Physiological nuclear TDP-43 was not detectable with these mAbs by immunohistochemistry and by immunoblot analyses. While the accumulation of phosphorylated C-terminal fragments was a robust finding in the cortical brain regions of FTLD-U and ALS, usually being much more abundant than the phosphorylated full-length TDP-43 band, spinal cord samples revealed a predominance of full-length TDP-43 over C-terminal fragments. This argues for a distinct TDP-43 species composition in inclusions in cortical versus spinal cord cells. Overall, these mAbs are powerful tools for the highly specific detection of disease-associated abnormal TDP-43 species and will be extremely useful for the neuropathological routine diagnostics of TDP-43 proteinopathies and for the investigation of emerging cellular and animal models for TDP-43 proteinopathie

Transportin 1 accumulates specifically with FET proteins but no other transportin cargos in FTLD-FUS and is absent in FUS inclusions in ALS with FUS mutations

Accumulation of the DNA/RNA binding protein fused in sarcoma (FUS) as inclusions in neurons and glia is the pathological hallmark of amyotrophic lateral sclerosis patients with mutations in FUS (ALS-FUS) as well as in several subtypes of frontotemporal lobar degeneration (FTLD-FUS), which are not associated with FUS mutations. Despite some overlap in the phenotype and neuropathology of FTLD-FUS and ALS-FUS, significant differences of potential pathomechanistic relevance were recently identified in the protein composition of inclusions in these conditions. While ALS-FUS showed only accumulation of FUS, inclusions in FTLD-FUS revealed co-accumulation of all members of the FET protein family, that include FUS, Ewing's sarcoma (EWS) and TATA-binding protein-associated factor 15 (TAF15) suggesting a more complex disturbance of transportin-mediated nuclear import of proteins in FTLD-FUS compared to ALS-FUS. To gain more insight into the mechanisms of inclusion body formation, we investigated the role of Transportin 1 (Trn1) as well as 13 additional cargo proteins of Transportin in the spectrum of FUS-opathies by immunohistochemistry and biochemically. FUS-positive inclusions in six ALS-FUS cases including four different mutations did not label for Trn1. In sharp contrast, the FET-positive pathology in all FTLD-FUS subtypes was also strongly labeled for Trn1 and often associated with a reduction in the normal nuclear staining of Trn1 in inclusion bearing cells, while no biochemical changes of Trn1 were detectable in FTLD-FUS. Notably, despite the dramatic changes in the subcellular distribution of Trn1 in FTLD-FUS, alterations of its cargo proteins were restricted to FET proteins and no changes in the normal physiological staining of 13 additional Trn1 targets, such as hnRNPA1, PAPBN1 and Sam68, were observed in FTLD-FUS. These data imply a specific dysfunction in the interaction between Trn1 and FET proteins in the inclusion body formation in FTLD-FUS. Moreover, the absence of Trn1 in ALS-FUS provides further evidence that ALS-FUS and FTLD-FUS have different underlying pathomechanism