High copy wildtype human 1N4R tau expression promotes early pathological tauopathy accompanied by cognitive deficits without progressive neurofibrillary degeneration.

INTRODUCTION: Accumulation of insoluble conformationally altered hyperphosphorylated tau occurs as part of the pathogenic process in Alzheimer's disease (AD) and other tauopathies. In most AD subjects, wild-type (WT) tau aggregates and accumulates in neurofibrillary tangles and dystrophic neurites in the brain; however, in some familial tauopathy disorders, mutations in the gene encoding tau cause disease. RESULTS: We generated a mouse model, Tau4RTg2652, that expresses high levels of normal human tau in neurons resulting in the early stages of tau pathology. In this model, over expression of WT human tau drives pre-tangle pathology in young mice resulting in behavioral deficits. These changes occur at a relatively young age and recapitulate early pre-tangle stages of tau pathology associated with AD and mild cognitive impairment. Several features distinguish the Tau4RTg2652 model of tauopathy from previously described tau transgenic mice. Unlike other mouse models where behavioral and neuropathologic changes are induced by transgenic tau harboring MAPT mutations pathogenic for frontotemporal lobar degeneration (FTLD), the mice described here express the normal tau sequence. CONCLUSIONS: Features of Tau4RTg2652 mice distinguishing them from other established wild type tau overexpressing mice include very early phenotypic manifestations, non-progressive tau pathology, abundant pre-tangle and phosphorylated tau, sparse oligomeric tau species, undetectable fibrillar tau pathology, stability of tau transgene copy number/expression, and normal lifespan. These results suggest that Tau4RTg2652 animals may facilitate studies of tauopathy target engagement where WT tau is driving tauopathy phenotypes.

The tau tubulin kinases TTBK1/2 promote accumulation of pathological TDP-43.

Pathological aggregates of phosphorylated TDP-43 characterize amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD-TDP), two devastating groups of neurodegenerative disease. Kinase hyperactivity may be a consistent feature of ALS and FTLD-TDP, as phosphorylated TDP-43 is not observed in the absence of neurodegeneration. By examining changes in TDP-43 phosphorylation state, we have identified kinases controlling TDP-43 phosphorylation in a C. elegans model of ALS. In this kinome-wide survey, we identified homologs of the tau tubulin kinases 1 and 2 (TTBK1 and TTBK2), which were also identified in a prior screen for kinase modifiers of TDP-43 behavioral phenotypes. Using refined methodology, we demonstrate TTBK1 and TTBK2 directly phosphorylate TDP-43 in vitro and promote TDP-43 phosphorylation in mammalian cultured cells. TTBK1/2 overexpression drives phosphorylation and relocalization of TDP-43 from the nucleus to cytoplasmic inclusions reminiscent of neuropathologic changes in disease states. Furthermore, protein levels of TTBK1 and TTBK2 are increased in frontal cortex of FTLD-TDP patients, and TTBK1 and TTBK2 co-localize with TDP-43 inclusions in ALS spinal cord. These kinases may represent attractive targets for therapeutic intervention for TDP-43 proteinopathies such as ALS and FTLD-TDP.

ADLAPH: A molecular haplotyping method based on allele-discriminating long-range PCR.

We present a method, called Allele-Discriminating Long and Accurate PCR Haplotyping (ADLAPH), for directly determining haplotypes from an extended genomic region. This method uses allele-discriminating primers in long-range PCR to amplify only one of the two chromosome homologues for the region of interest. Haplotypes are then determined from these phase-separated PCR fragments by conventional single nucleotide polymorphism (SNP) genotyping methods. This simple robust procedure makes it practical for high-throughput haplotyping of unrelated individuals, and potentially allows direct observation of haplotype information for up to 40 kb or more. We demonstrate the feasibility of this molecular haplotyping procedure by generating apolipoprotein E (APOE) haplotypes from 100 unrelated subjects.