Naslov
Pathological tau proteins in agryrophilic grain disease

Autori
Šimić, Goran

Izvornik
Lancet Neurology (1473-3099) 1 (2002), 5; 276-276, CC entry week 40/2002 Clinical medicine / Neurology

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, osvrt, znanstveni

Ključne riječi
argyrophilic grain disease; tau protein; electrophoresis; tauopathy; cerebrospinal fluid; corticobasal degeneration; progressive supranuclear palsy

Sažetak
Argyrophilic grain disease (AGD) is a cause of adult-onset progressive dementia (also called Braak's dementia) that is characterised by spindle-shape argyrophilic grains (ArGs) found within neuronal processes. ArGs are mainly found in the CA1 subfield of the Ammon's horn, entorhinal and transentorhinal cortices, the amygdala and the hypothalamic lateral tuberal nuclei. In addition, tau-positive oligodendrocytes ('coiled bodies') are seen in the white matter and deep cortical layers. In a study of 2661 non-selected brains at autopsy, AGD was found in 5% of individuals aged between 51 and 96 years. The finding that 6% of individuals from the same population had fully-developed Alzheimer's disease supports the view that AGD is an underestimated cause of dementia in old patients. The clinical features of AGD depend on the quantity and anatomical distribution of argyrophilic grains. Recent studies have highlighted memoy disturbance and personality change characterised by emotional imbalance with aggression or ill temper as symptoms of the disease. Although it is known that ArGs contain hyperphosphorylated tau, the isoform composition of the grains has not been clarified. This is presumably because grains have not been isolated to homogeneity and biochemical analysis is confounded by concomitant Alzheimer's neurofibrillary pathology. The results have shown both biochemically and immunocytochemically that ArGs are composed of hyperphosphorylated tau enriched in 4R tau (tau proteins bind microtubules via highly-conserved repetitive domains R1-R4 that regulate the rate of microtubule polymerisation and are encoded by exons 9 to 12 ; alternative splicing of exon 10 give rise to tau isoforms with 3R (without exon 10) and 4R (with exon 10)). AGD can be therefore considered as a sporadic 4R tauopathy, sharing a common genetic risk factor with progressive supranuclear palsy (PSP) and cortico-basal degeneration (CBD) (increased H1 haplotype?). Since about 20% of patients with PSP, and 40% of patients with CBD, have AGD and 'grain-like' lesions in PSP and CBD are not restricted to limbic lobe and hypothalamus, 4R tauopathies may represent a disease spectrum. The medial temporal lobe tauopathy seen in AGD is intermediate between a diffuse cortical and subcortical tauopathy of CBD and the more restricted basal ganglia and brainstem tauopathy of PSP. It is hoped that more accurate biological analysis of cerebrospinal fluid in the future will help to discriminate between tau protein types present in physiological conditions and tau released during the progression of a particular neurodegenerative disease.

Izvorni jezik
Engleski

Znanstvena područja
Kliničke medicinske znanosti

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