Here, we report that, in the absence of other components, TDP-43 spontaneously forms aggregates bearing remarkable ultrastructural similarities to TDP-43 deposits in degenerating neurons of ALS and FTLD-U patients [corrected] .
Advances in genetics and pathology have supported the idea of a continuum between frontotemporal dementia (FTD) and motor neurone disease (MND), which is strengthened by the discovery of the trans-activating responsive (Tar) sequence DNA binding protein (TDP-43) as a key component in the underlying pathology of FTD, FTD-MND and sporadic and familial MND patients.
These findings reveal an essential role for TDP-43 in dendritic structural integrity, supporting the notion that loss of normal TDP-43 function in diseased neurons may compromise neuronal connectivity before neuronal cell loss in FTD and ALS.
Of the 100, 34 have died, with pathological confirmation in 24; 18 had frontotemporal lobar degeneration with ubiquitin-positive inclusions (13 of 13 confirmed TAR DNA binding protein-43 positive), and 3 had classic tau-positive Pick bodies and 3 had Alzheimer's pathology.
We describe novel transactivation response DNA-binding protein of 43 kd (TDP-43)-positive structures in the brains of patients with frontotemporal lobar degeneration with ubiquitin-positive inclusions and familial Lewy body disease.
TDP-43 proteinopathy (amyotrophic lateral sclerosis and frontotemporal lobar degeneration with ubiquitin-positive inclusions) is a newly categorized group of neurodegenerative disorders characterized by abnormal accumulation and mislocalization of nuclear TDP-43 protein in the neuronal cytoplasm.
Four hundred thirty-four patients with FTD, including primary progressive aphasia, semantic dementia, FTD/amyotrophic lateral sclerosis (ALS), FTD/motor neuron disease, corticobasal syndrome/corticobasal degeneration, progressive supranuclear palsy, Pick disease, dementia lacking distinctive histopathology, and pathologically confirmed cases of frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U); and 111 non-FTD cases (controls) in which TDP-43 deposits were a prominent neuropathological feature, including subjects with ALS, Guam ALS and/or parkinsonism dementia complex, Guam dementia, Alzheimer disease, multiple system atrophy, and argyrophilic grain disease.
Pathology showed typical PD-type Lewy body disease (LBD) in most patients, whereas in others there was 'pure' nigral degeneration (one with TDP-43-positive inclusions), diffuse LBD, or tau-, alpha-synuclein- or ubiquitin-positive pathology reminiscent of progressive supranuclear gaze palsy, multisystem atrophy, and frontotemporal dementia with ubiquitin-positive inclusions.
Since the identification of phosphorylated and truncated transactive response DNA-binding protein 43 (TDP-43) as a primary component of ubiquitinated inclusions in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin-positive inclusions, and the discovery that mutations in the TDP-43 gene cause ALS, much effort has been directed towards establishing how TDP-43 contributes to the development of neurodegeneration.
In this Review, we summarize the current evidence regarding the normal function of TDP-43 and the TDP-43 pathology observed in FTLD-TDP, ALS, and other neurodegenerative diseases wherein TDP-43 pathology co-occurs with other disease-specific lesions (for example, with amyloid plaques and neurofibrillary tangles in Alzheimer disease).
TDP-43 positive inclusions are also a feature of amyotrophic lateral sclerosis pathology, corroborating the observation of overlapping clinical features between the two conditions and reaffirming the FTD-ALS disease spectrum.
Transactivation response DNA-binding protein 43 (TDP-43) is a principal component of ubiquitinated inclusions in frontotemporal lobar degeneration with ubiquitin-positive inclusions and in amyotrophic lateral sclerosis (ALS).
The seminal discoveries of accumulation of TDP-43 in most cases of ALS and the most frequent form of FTD, frontotemporal lobar degeneration with ubiquitinated inclusions, followed by identification of FUS as the novel pathological protein in a small subset of patients with ALS and various FTD subtypes provide clear evidence that these disorders are related.