Patient-derived frontotemporal lobar degeneration brain extracts induce formation and spreading of TDP-43 pathology in vivo.

The stereotypical distribution of TAR DNA-binding 43 protein (TDP-43) aggregates in frontotemporal lobar degeneration (FTLD-TDP) suggests that pathological TDP-43 spreads throughout the brain via cell-to-cell transmission and correlates with disease progression, but no in vivo experimental data support this hypothesis. We first develop a doxycycline-inducible cell line expressing GFP-tagged cytoplasmic TDP-43 protein (iGFP-NLSm) as a cell-based system to screen and identify seeding activity of human brain-derived pathological TDP-43 isolated from sporadic FTLD-TDP and familial cases with Granulin (FTLD-TDP-GRN) or C9orf72 repeat expansion mutations (FTLD-TDP-C9+). We demonstrate that intracerebral injections of biologically active pathogenic FTLD-TDP seeds into transgenic mice expressing cytoplasmic human TDP-43 (lines CamKIIa-hTDP-43, rNLS8, and CamKIIa-208) and non-transgenic mice led to the induction of de-novo TDP-43 pathology.

Neuron loss and degeneration in the progression of TDP-43 in frontotemporal lobar degeneration.

Frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP) is associated with the accumulation of pathological neuronal and glial intracytoplasmic inclusions as well as accompanying neuron loss. We explored if cortical neurons detected by NeuN decreased with increasing TDP-43 inclusion pathology in the postmortem brains of 63 patients with sporadic and familial FTLD-TDP. Semi-automated quantitative algorithms to quantify histology in tissue sections stained with antibodies specific for pathological or phosphorylated TDP-43 (pTDP-43) and NeuN were developed and validated in affected (cerebral cortex) and minimally affected (cerebellar cortex) brain regions of FTLD-TDP cases.

Expansion of the classification of FTLD-TDP: distinct pathology associated with rapidly progressive frontotemporal degeneration.

Frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP) can typically be categorized into one of four distinct histopathologic patterns of TDP-43 pathology, types A to D. The strength of this histopathologic classification lies in the association between FTLD-TDP subtypes and various clinical and genetic features of disease. Seven cases of FTLD-TDP were identified here which were difficult to classify based on existing pathologic criteria.

Tauopathy with hippocampal 4-repeat tau immunoreactive spherical inclusions: a report of three cases.

Tauopathies are a major group of neurodegenerative proteinopathies characterized by the accumulation of abnormal and hyperphosphorylated tau proteins in the brain. Tau pathology is characterized as 3R (repeat) or 4R predominant or mixed 3R and 4R type. Here we report three cases lacking mutations in the microtubule associated protein tau (MAPT) gene with unusual tau pathology.

Progression of motor neuron disease is accelerated and the ability to recover is compromised with advanced age in rNLS8 mice.

In order to treat progressive paralysis in ALS patients, it is critical to develop a mouse that closely models human ALS in both pathology and also in the timing of these events. We have recently generated new TDP-43 bigenic mice (called rNLS8) with doxycycline (Dox)-suppressible expression of human TDP-43 (hTDP-43) harboring a defective nuclear localization signal (hTDP-43∆NLS) under the control of the NEFH promoter. Our previous studies characterized the pathology and disease course in young rNLS8 mice following induction of neuronal hTDP-43ΔNLS.

Selective Motor Neuron Resistance and Recovery in a New Inducible Mouse Model of TDP-43 Proteinopathy.

Unlabelled: Motor neurons (MNs) are the neuronal class that is principally affected in amyotrophic lateral sclerosis (ALS), but it is widely known that individual motor pools do not succumb to degeneration simultaneously. Because >90% of ALS patients have an accumulation of cytoplasmic TDP-43 aggregates in postmortem brain and spinal cord (SC), it has been suggested that these inclusions in a given population may trigger its death. We investigated seven MN pools in our new inducible rNLS8 transgenic (Tg) mouse model of TDP-43 proteinopathy and found striking differences in MN responses to TDP-43 pathology.

Transcriptomic Changes Due to Cytoplasmic TDP-43 Expression Reveal Dysregulation of Histone Transcripts and Nuclear Chromatin.

TAR DNA-binding protein 43 (TDP-43) is normally a nuclear RNA-binding protein that exhibits a range of functions including regulation of alternative splicing, RNA trafficking, and RNA stability. However, in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP), TDP-43 is abnormally phosphorylated, ubiquitinated, and cleaved, and is mislocalized to the cytoplasm where it forms distinctive aggregates. We previously developed a mouse model expressing human TDP-43 with a mutation in its nuclear localization signal (ΔNLS-hTDP-43) so that the protein preferentially localizes to the cytoplasm.

An insoluble frontotemporal lobar degeneration-associated TDP-43 C-terminal fragment causes neurodegeneration and hippocampus pathology in transgenic mice.

Frontotemporal dementia (FTD) causes progressive personality, behavior and/or language disturbances and represents the second most common form of dementia under the age of 65. Over half of all FTD cases are classified pathologically as frontotemporal lobar degeneration (FTLD) with TAR DNA-binding protein of 43 kDa (TDP-43) pathology (FTLD-TDP). In FTLD-TDP brains, TDP-43 is phosphorylated, C-terminally cleaved, lost from the nucleus and accumulates in the cytoplasm and processes of neurons and glia.

Functional recovery in new mouse models of ALS/FTLD after clearance of pathological cytoplasmic TDP-43.

Accumulation of phosphorylated cytoplasmic TDP-43 inclusions accompanied by loss of normal nuclear TDP-43 in neurons and glia of the brain and spinal cord are the molecular hallmarks of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD-TDP). However, the role of cytoplasmic TDP-43 in the pathogenesis of these neurodegenerative TDP-43 proteinopathies remains unclear, due in part to a lack of valid mouse models. We therefore generated new mice with doxycycline (Dox)-suppressible expression of human TDP-43 (hTDP-43) harboring a defective nuclear localization signal (∆NLS) under the control of the neurofilament heavy chain promoter.

Drosha inclusions are new components of dipeptide-repeat protein aggregates in FTLD-TDP and ALS C9orf72 expansion cases.

Frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) are 2 neurodegenerative disorders that share clinical, genetic, and neuropathologic features. The presence of abnormal expansions of GGGGCC repeats (G4C2 repeats) in a noncoding region of the Chromosome 9 open reading frame 72 (C9orf72) gene is the major genetic cause of both FTLD and ALS. Transcribed G4C2 repeats can form nuclear RNA foci and recruit RNA-binding proteins, thereby inhibiting their normal function.

Novel monoclonal antibodies to normal and pathologically altered human TDP-43 proteins.

The RNA/DNA-binding protein, TDP-43, is the key component of ubiquitinated inclusions characteristic of amyotrophic lateral sclerosis (ALS) and the majority of frontotemporal lobar degeneration (FTLD-TDP) referred to collectively as TDP-43 proteinopathies. To further elucidate mechanisms of pathological TDP-43 processing and identify TDP-43 epitopes that could be useful as potential biomarkers of TDP-43 proteinopathies, we developed a panel of novel monoclonal antibodies (MAbs) directed at regions extending across the length of TDP-43. Here, we confirm previous observations that there is no or minimal accumulation of TDP-43 N-terminal domains in neocortical inclusions in human TDP-43 proteinopathy tissues and we identify a subset of these MAbs that are specific for human versus mouse TDP-43.

Distinct α-synuclein strains differentially promote tau inclusions in neurons.

Many neurodegenerative diseases are characterized by the accumulation of insoluble protein aggregates, including neurofibrillary tangles comprised of tau in Alzheimer's disease and Lewy bodies composed of α-synuclein in Parkinson's disease. Moreover, different pathological proteins frequently codeposit in disease brains. To test whether aggregated α-synuclein can directly cross-seed tau fibrillization, we administered preformed α-synuclein fibrils assembled from recombinant protein to primary neurons and transgenic mice.

Stages of pTDP-43 pathology in amyotrophic lateral sclerosis.

Objective: To see whether the distribution patterns of phosphorylated 43kDa TAR DNA-binding protein (pTDP-43) intraneuronal inclusions in amyotrophic lateral sclerosis (ALS) permit recognition of neuropathological stages.

Methods: pTDP-43 immunohistochemistry was performed on 70 μm sections from ALS autopsy cases (N = 76) classified by clinical phenotype and genetic background.

Results: ALS cases with the lowest burden of pTDP-43 pathology were characterized by lesions in the agranular motor cortex, brainstem motor nuclei of cranial nerves V, VII, and X-XII, and spinal cord α-motoneurons (stage 1).

TDP-43 skeins show properties of amyloid in a subset of ALS cases.

Aggregation of TDP-43 proteins to form intracellular inclusions is the primary pathology in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) with TDP-43 inclusions (FTLD-TDP). Histologically, in the cerebral cortex and limbic regions of affected ALS and FTLD-TDP patients, these pathologies occur as a variety of cytoplasmic, neuritic and intranuclear TDP-43 inclusions. In the spinal cord and lower brainstem of ALS patients, the lesions form cytoplasmic dashes or complex filamentous and spherical profiles in addition to skein-like inclusions (SLI).

TMEM106B, the risk gene for frontotemporal dementia, is regulated by the microRNA-132/212 cluster and affects progranulin pathways.

Frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP) is a fatal neurodegenerative disease with no available treatments. Mutations in the progranulin gene (GRN) causing impaired production or secretion of progranulin are a common Mendelian cause of FTLD-TDP; additionally, common variants at chromosome 7p21 in the uncharacterized gene TMEM106B were recently linked by genome-wide association to FTLD-TDP with and without GRN mutations. Here we show that TMEM106B is neuronally expressed in postmortem human brain tissue, and that expression levels are increased in FTLD-TDP brain.

Pattern of ubiquilin pathology in ALS and FTLD indicates presence of C9ORF72 hexanucleotide expansion.

C9ORF72-hexanucleotide repeat expansions and ubiquilin-2 (UBQLN2) mutations are recently identified genetic markers in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). We investigate the relationship between C9ORF72 expansions and the clinical phenotype and neuropathology of ALS and FTLD. Genetic analysis and immunohistochemistry (IHC) were performed on autopsy-confirmed ALS (N = 75), FTLD-TDP (N = 30), AD (N = 14), and controls (N = 11).

The acetylation of tau inhibits its function and promotes pathological tau aggregation.

The microtubule associated protein tau promotes neuronal survival through binding and stabilization of MTs. Phosphorylation regulates tau-microtubule interactions and hyperphosphorylation contributes to the aberrant formation of insoluble tau aggregates in Alzheimer's disease (AD) and related tauopathies. However, other pathogenic post-translational tau modifications have not been well characterized.

Motor neuron disease clinically limited to the lower motor neuron is a diffuse TDP-43 proteinopathy.

Motor neuron disease (MND) may present as an isolated lower motor neuron (LMN) disorder. Although the significance of pathological 43 kDa transactive responsive sequence DNA binding protein (TDP-43) for amyotrophic lateral sclerosis (ALS) was appreciated only recently, the topographical distribution of TDP-43 pathology in MND clinically isolated to the LMN versus normal controls (COs) is only incompletely described. Therefore, we performed longitudinal clinical evaluation and retrospective chart review of autopsied patients diagnosed with isolated LMN disease.

Dysregulation of the ALS-associated gene TDP-43 leads to neuronal death and degeneration in mice.

Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are characterized by cytoplasmic protein aggregates in the brain and spinal cord that include TAR-DNA binding protein 43 (TDP-43). TDP-43 is normally localized in the nucleus with roles in the regulation of gene expression, and pathological cytoplasmic aggregates are associated with depletion of nuclear protein. Here, we generated transgenic mice expressing human TDP-43 with a defective nuclear localization signal in the forebrain (hTDP-43-ΔNLS), and compared them with mice expressing WT hTDP-43 (hTDP-43-WT) to determine the effects of mislocalized cytoplasmic TDP-43 on neuronal viability.

Pathological 43-kDa transactivation response DNA-binding protein in older adults with and without severe mental illness.

Background: Major psychiatric diseases such as schizophrenia and mood disorders have not been linked to a specific pathology, but their clinical features overlap with some aspects of the behavioral variant of frontotemporal lobar degeneration. Although the significance of pathological 43-kDa (transactivation response) DNA-binding protein (TDP-43) for frontotemporal lobar degeneration was appreciated only recently, the prevalence of TDP-43 pathology in patients with severe mental illness vs controls has not been systematically addressed.

Objective: To examine patients with chronic psychiatric diseases, mainly schizophrenia, for evidence of neurodegenerative TDP-43 pathology in comparison with controls.

Global analysis of gene activity during Arabidopsis seed development and identification of seed-specific transcription factors.

Most of the transcription factors (TFs) responsible for controlling seed development are not yet known. To identify TF genes expressed at specific stages of seed development, including those unique to seeds, we used Affymetrix GeneChips to profile Arabidopsis genes active in seeds from fertilization through maturation and at other times of the plant life cycle. Seed gene sets were compared with those expressed in prefertilization ovules, germinating seedlings, and leaves, roots, stems, and floral buds of the mature plant.

Amyotrophic lateral sclerosis, frontotemporal dementia and beyond: the TDP-43 diseases.

Ever since the significance of pathological 43-kDa transactivating responsive sequence DNA-binding protein (TDP-43) for human disease has been recognized in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin positive inclusions (FTLD-U), a number of publications have emerged reporting on this pathology in a variety of neurodegenerative diseases. Given the heterogeneous and, in part, conflicting nature of the recent findings, we here review pathological TDP-43 and its relationship to human disease with a special focus on ALS and FTLD-U. To this end, we propose a classification scheme in which pathological TDP-43 is the major disease defining pathology in one group, or is present in addition to other neurodegenerative hallmark pathologies in a second category.

Clinical and pathological continuum of multisystem TDP-43 proteinopathies.

Objective: To determine the extent of transactivation response DNA-binding protein with a molecular weight of 43 kDa (TDP-43) pathology in the central nervous system of patients with clinically and autopsy-confirmed diagnoses of frontotemporal lobar degeneration with and without motor neuron disease and amyotrophic lateral sclerosis with and without cognitive impairment.

Design: Performance of immunohistochemical whole-central nervous system scans for evidence of pathological TDP-43 and retrospective clinical medical record review.

Setting: An academic medical center.

Expression of TDP-43 C-terminal Fragments in Vitro Recapitulates Pathological Features of TDP-43 Proteinopathies.

The disease protein in frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U) and amyotrophic lateral sclerosis (ALS) was identified recently as the TDP-43 (TAR DNA-binding protein 43), thereby providing a molecular link between these two disorders. In FTLD-U and ALS, TDP-43 is redistributed from its normal nuclear localization to form cytoplasmic insoluble aggregates. Moreover, pathological TDP-43 is abnormally ubiquitinated, hyperphosphorylated, and N-terminally cleaved to generate C-terminal fragments (CTFs).