TDP-43 aggregation inside micronuclei reveals a potential mechanism for protein inclusion formation in ALS.

Amyotrophic lateral sclerosis (ALS) is a devastating progressive neurodegenerative disease with no known etiology. The formation of pathological protein inclusions, including RNA-binding proteins such as TDP-43 and rho guanine nucleotide exchange factor (RGNEF) are a hallmark of ALS. Despite intensive research, the mechanisms behind protein aggregate formation in ALS remains unclear.

Tau protein phosphorylation at Thr initiates fibril formation via accessibility of the N-terminal phosphatase-activating domain.

One of the neuropathological hallmarks of the tauopathies is the formation of neuronal cytoplasmic inclusions and fibrils of microtubule-associated tau protein (tau). The phosphorylation of Thr of tau (pThr tau) appears to be sufficient for fibril formation in vitro and in vivo, but the mechanism by which this initiates fibril formation is unknown. Using transient transfections of tau mutants into HEK293T cells, we determined that the phosphorylation of Thr leads to exposure of the tau N-terminal phosphatase-activating domain (PAD).

Synergistic toxicity in an in vivo model of neurodegeneration through the co-expression of human TDP-43 and tau protein.

Although it has been suggested that the co-expression of multiple pathological proteins associated with neurodegeneration may act synergistically to induce more widespread neuropathology, experimental evidence of this is sparse. We have previously shown that the expression of ThrAsp-tau (tau) using somatic gene transfer with a stereotaxically-injected recombinant adeno-associated virus (rAAV9) vector induces tau pathology in rat hippocampus. In this study, we have examined whether the co-expression of human tau with mutant human TDP-43 (TDP-43) will act synergistically.

Neurofilament Immunohistochemistry Followed by Luxol Fast Blue, for Staining Axons and Myelin in the Same Paraffin Section of Spinal Cord.

Many disorders of the central nervous system are characterized by both axonal pathology and demyelination. In assessing this concurrent pathology, techniques for staining axons or myelin are frequently used separately. Here we report the development of a combined immunohistochemical and tinctorial staining technique in which we have modified the Luxol fast blue myelin stain to be used in conjunction with a diaminobenzidine-based immunohistochemical stain for high molecular weight neurofilament (SMI-31).

Somatic Gene Transfer Using a Recombinant Adenoviral Vector (rAAV9) Encoding Pseudophosphorylated Human Thr175 Tau in Adult Rat Hippocampus Induces Tau Pathology.

Aberrant phosphorylation of the microtubule associated protein tau (tau) is associated with multiple neurodegenerative diseases where it is a contributes to neurotoxicity. We have observed that phosphorylation at Thr175 tau (pThr175 tau) exerts toxicity when expressed as a pseudophosphorylated tau construct (Thr175Asp) in vitro. To determine whether pThr175 tau can induce tau pathology in vivo with an accompanying clinical phenotype, we used a recombinant adenoviral expression vector (rAAV9) to express a GFP-tagged Thr175Asp tau protein construct in adult female Sprague-Dawley rat hippocampus.

Phosphorylation of Threonine 175 Tau in the Induction of Tau Pathology in Amyotrophic Lateral Sclerosis-Frontotemporal Spectrum Disorder (ALS-FTSD). A Review.

Approximately 50-60% of all patients with amyotrophic lateral sclerosis (ALS) will develop a deficit of frontotemporal function, ranging from frontotemporal dementia (FTD) to one or more deficits of neuropsychological, speech or language function which are collectively known as the frontotemporal spectrum disorders of ALS (ALS-FTSD). While the neuropathology underlying these disorders is most consistent with a widespread alteration in the metabolism of transactive response DNA-binding protein 43 (TDP-43), in both ALS with cognitive impairment (ALSci) and ALS with FTD (ALS-FTD; also known as MND-FTD) there is evidence for alterations in the metabolism of the microtubule associated protein tau. This alteration in tau metabolism is characterized by pathological phosphorylation at residue Thr (pThr tau) which is associated with activation of GSK3β (pTyrGSK3β), phosphorylation of Thrtau, and the formation of cytoplasmic inclusions with increased rates of cell death.

TDP-43 regulates the alternative splicing of hnRNP A1 to yield an aggregation-prone variant in amyotrophic lateral sclerosis.

See Fratta and Isaacs (doi:10.1093/brain/awy091) for a scientific commentary on this article.The RNA binding proteins TDP-43 (encoded by TARDBP) and hnRNP A1 (HNRNPA1) are each mutated in certain amyotrophic lateral sclerosis cases and are often mislocalized in cytoplasmic aggregates within motor neurons of affected patients.

Pathologic Thr tau phosphorylation in CTE and CTE with ALS.

Objective: To investigate whether chronic traumatic encephalopathy (CTE) and CTE with amyotrophic lateral sclerosis (CTE-ALS) exhibit features previously observed in other tauopathies of pathologic phosphorylation of microtubule-associated protein tau at Thr (pThr tau) and Thr (pThr tau), and glycogen synthase kinase-3β (GSK3β) activation, and whether these pathologic features are a consequence of traumatic brain injury (TBI).

Methods: Tau isoform expression was assayed by western blot in 6 stage III CTE cases. We also used immunohistochemistry to analyze 5 cases each of CTE, CTE-ALS, and 5 controls for expression of activated GSK3β, pThr tau, pThr tau, and oligomerized tau within spinal cord tissue and hippocampus.

Threonine, a novel pathological phosphorylation site on tau protein linked to multiple tauopathies.

Microtubule associated protein tau (tau) deposition is associated with a spectrum of neurodegenerative diseases collectively termed tauopathies. We have previously shown that amyotrophic lateral sclerosis (ALS) with cognitive impairment (ALSci) is associated with tau phosphorylation at Thr and that this leads to activation of GSK3β which then induces phosphorylation at tau Thr. This latter step leads to dissociation of tau from microtubules and pathological tau fibril formation.

Thr175-phosphorylated tau induces pathologic fibril formation via GSK3β-mediated phosphorylation of Thr231 in vitro.

We have previously shown that amyotrophic lateral sclerosis with cognitive impairment can be characterized by pathologic inclusions of microtubule-associated protein tau (tau) phosphorylated at Thr(175) (pThr(175)) in association with GSK3β activation. We have now examined whether pThr(175) induces GSK3β activation and whether this leads to pathologic fibril formation through Thr(231) phosphorylation. Seventy-two hours after transfection of Neuro2A cells with pseudophosphorylated green fluorescent protein-tagged 2N4R tau (Thr(175)Asp), phosphorylated kinase glycogen synthase kinase 3 beta (active GSK3β) levels were significantly increased as was pathologic fibril formation and cell death.

Prevalence of bruxism in children with episodic migraine--a case-control study with polysomnography.

Background: Parents of children with migraine have described a higher prevalence of sleep bruxism and other sleep disturbances in their children. The objective of this study was to use polysomnography to investigate the prevalence of bruxism during sleep in children with episodic migraine relative to controls.

Findings: Controls and patients were matched by sex, age, years of formal education, presence of snoring, arousals per hour, and respiratory events per hour.

Mortality associated with periodic limb movements during sleep in amyotrophic lateral sclerosis patients.

Objective: To describe the prevalence and severity of periodic limb movements during sleep in amyotrophic lateral sclerosis patients and to explore this fact as a predictor of severity of the condition with respect to mortality.

Methods: In this case-control study, questionnaire and polysomnographic data were analyzed from 35 amyotrophic lateral sclerosis patients. Controls were matched by age, genre, and body mass index.