ABSTRACT
Recessively inherited loss-of-function mutations in the PTEN-induced putative kinase 1(Pink1), DJ-1 (Park7) and Parkin (Park2) genes are linked to familial cases of early-onset Parkinson's disease (PD). As part of its strategy to provide more tools for the research community, The Michael J. Fox Foundation for Parkinson's Research (MJFF) funded the generation of novel rat models with targeted disruption ofPink1, DJ-1 or Parkin genes and determined if the loss of these proteins would result in a progressive PD-like phenotype. Pathological, neurochemical and behavioral outcome measures were collected at 4, 6 and 8months of age in homozygous KO rats and compared to wild-type (WT) rats. Both Pink1 and DJ-1 KO rats showed progressive nigral neurodegeneration with about 50% dopaminergic cell loss observed at 8 months of age. ThePink1 KO and DJ-1 KO rats also showed a two to three fold increase in striatal dopamine and serotonin content at 8 months of age. Both Pink1 KO and DJ-1 KO rats exhibited significant motor deficits starting at 4months of age. However, Parkin KO rats displayed normal behaviors with no neurochemical or pathological changes. These results demonstrate that inactivation of the Pink1 or DJ-1 genes in the rat produces progressive neurodegeneration and early behavioral deficits, suggesting that these recessive genes may be essential for the survival of dopaminergic neurons in the substantia nigra (SN). These MJFF-generated novel rat models will assist the research community to elucidate the mechanisms by which these recessive genes produce PD pathology and potentially aid in therapeutic development.
Subject(s)
Microtubule-Associated Proteins/deficiency , Parkinsonian Disorders/physiopathology , Phenotype , Protein Kinases/deficiency , Ubiquitin-Protein Ligases/deficiency , Aging , Animals , Animals, Genetically Modified , Brain/pathology , Brain/physiopathology , Dopamine/metabolism , Dopaminergic Neurons/pathology , Dopaminergic Neurons/physiology , Gene Knockout Techniques , Genes, Recessive , Male , Microtubule-Associated Proteins/genetics , Motor Activity/physiology , Parkinsonian Disorders/genetics , Parkinsonian Disorders/pathology , Protein Deglycase DJ-1 , Protein Kinases/genetics , Rats, Long-Evans , Serotonin/metabolism , Ubiquitin-Protein Ligases/geneticsABSTRACT
CONTEXT: Assessing the amount of globotriaosylceramide inclusions in renal peritubular capillaries by a semiquantitative approach is a standard and useful measure of therapeutic efficacy in Fabry disease, achievable by light microscopy analysis. OBJECTIVE: To describe a novel virtual microscopy quantitative method to measure globotriaosylceramide inclusions (Barisoni Lipid Inclusion Scoring System [BLISS]) in renal biopsies from patients with Fabry disease. DESIGN: Plastic embedded 1-µm-thick sections from kidney biopsies from 17 patients enrolled in a Fabry disease clinical trial were evaluated using a standard semiquantitative methodology and BLISS to compare sensitivity. We also tested intrareader and interreader variability of BLISS and compared results from conventional light microscopy analysis with a virtual microscopy-based methodology. Peritubular capillaries were first annotated on digital images of whole slides by 1 pathologist and then scored for globotriaosylceramide inclusions by 2 additional pathologists. RESULTS: We demonstrated that (1) quantitative analysis by BLISS results in detection of small amount of globotriaosylceramide inclusions even when by semiquantitative analysis the score is 0, (2) application of BLISS combined with conventional light microscopy results in low intrareader and interreader variability, and (3) BLISS combined with virtual microscopy results in significant reduction of intrareader and interreader variability compared with BLISS-light microscopy. CONCLUSIONS: BLISS is a simpler and more sensitive scoring system compared to the semiquantitative approach. The virtual microscopy-based methodology increases accuracy and reproducibility; moreover, it provides a permanent record of retrievable data with full transparency in clinical trials.
