Isolated RING2 domain of parkin is sufficient for E2-dependent E3 ligase activity.

The E3 ubiquitin ligase activity of the parkin protein is implicated in playing a protective role against neurodegenerative disorders including Parkinson's, Huntington's, and Alzheimer's diseases. Parkin has four zinc-containing domains: RING0, RING1, IBR (in-between ring), and RING2. Mutational analysis of full-length parkin suggests that the C-terminal RING2 domain contains the catalytic core.

Parkin, A Top Level Manager in the Cell's Sanitation Department.

Parkin belongs to a class of multiple RING domain proteins designated as RBR (RING, in between RING, RING) proteins. In this review we examine what is known regarding the structure/function relationship of the Parkin protein. Parkin contains three RING domains plus a ubiquitin-like domain and an in-between-RING (IBR) domain.

Assessing the toxicity of tau aggregation.

Abnormally phosphorylated and aggregated tau protein is the primary component of pathological structures that are closely associated with neurodegeneration in Alzheimer's disease, Pick disease, corticobasal degeneration, progressive supranuclear palsy and many other neurodegenerative tauopathies, leading to the hypothesis that these structures are toxic mediators of disease progression. Results from animal models designed to test this hypothesis have yielded evidence that can suggest either a pathogenic, beneficial, or incidental role for tau aggregation. This review summarizes the differences in construction of recent model systems and assay methods that examine tau pathology and toxicity.

Pre-assembled tau filaments phosphorylated by GSK-3b form large tangle-like structures.

Hyperphosphorylated tau protein is a major component of neurofibrillary tangles, a prominent intracellular hallmark of Alzheimer's disease. Both hyperphosphorylated tau and neurofibrillary tangles have been shown to correlate with dementia in Alzheimer's disease, but the relationship between hyperphosphorylation and tangle formation is not clear. Using a cell-free in vitro model system, in which tau polymerization is induced by arachidonic acid, we show that GSK-3beta phosphorylation of pre-assembled tau filaments makes those filaments prone to coalesce into large neurofibrillary tangle-like structures.

A complex mechanism for inducer mediated tau polymerization.

The accumulation of polymers of the microtubule associated protein tau is correlative with increased neurodegeneration in Alzheimer's disease and other related tauopathies. In vitro models have been developed in order to investigate molecular mechanisms that regulate the polymerization of tau. Arachidonic acid and heparin have been proposed to induce tau polymerization via a ligand dependent nucleation-elongation mechanism.

Tau phosphorylation by GSK-3beta promotes tangle-like filament morphology.

Background: Neurofibrillary tangles (NFTs) are intraneuronal aggregates associated with several neurodegenerative diseases including Alzheimer's disease. These abnormal accumulations are primarily comprised of fibrils of the microtubule-associated protein tau. During the progression of NFT formation, disperse and non-interacting tau fibrils become stable aggregates of tightly packed and intertwined filaments.

A one-carbon modification of protein lysine associated with elevated oxidative stress in human substantia nigra.

We describe for the first time a naturally occurring lysine modification that is converted to methyllysine by reduction with sodium borohydride. This modification is approximately 1.7 times as abundant in soluble proteins from human substantia nigra pars compacta as in proteins from other brain regions, possibly as a result of elevated oxidative stress in the nigra.

Pseudo-phosphorylation of tau at Ser202 and Thr205 affects tau filament formation.

The microtubule-associated protein tau aggregates into insoluble filaments in numerous neurodegenerative diseases, most common of which is Alzheimer's disease. Tau aggregation in Alzheimer's disease appears to follow a continuum from soluble monomer to an end point of insoluble extracellular tangles with a strong correlation between the amount of fibrillar tau and dementia. The phosphorylation of amino acids S202 and T205 in the tau molecule is recognized by the phosphorylation-specific monoclonal antibody, AT8, and has been observed by a number of researchers to be an early step in the progression of monomer to filaments.

Development of autosomal recessive polycystic kidney disease in BALB/c-cpk/cpk mice.

Autosomal recessive polycystic kidney disease (ARPKD) is a rare but devastating inherited disease in humans. Various strains of mice that are homozygous for the cpk gene display renal pathology similar to that seen in human ARPKD. The PKD progresses to renal insufficiency, azotemia, and ultimately a uremic death by approximately 3 wk of age.