Genes: PRKN (parkin)
Modification: PRKN (parkin): Knock-Out
Disease Relevance: Parkinson's Disease
Strain Name: LEH-Park2TM1sage
Genetic Background: Long Evans Hooded
Availability: Available through Horizon Discovery (formerly Sage Labs); TGRL4760; Live.
This knockout rat model was created at Sage Labs (now Horizon) in collaboration with the Michael J. Fox Foundation. It carries a disrupted Park2 gene, which encodes the E3 ligase parkin. Homozygous rats exhibit normal behavior and have no significant degeneration of striatal neurons or loss of dopamine (Dave et al., 2014).
The rat Park2 gene was disrupted using zinc finger nuclease (ZFN) technology, in which targeted ZFN RNA was injected into fertilized eggs. The ZFNs were engineered to bind to a recognition site sequence in exon 4 of Park2 and cleave the DNA. When the resulting double strand break was repaired by non-homologous end joining, a deletion of five base pairs was created in the founder rat. This deletion led to a frame shift and the creation of a premature stop codon. Parkin mRNA levels were decreased by about half in the brains of Parkin KO rats. The protein was undetectable by western blot.
Homozygous rats appeared normal at birth. Their behavior was assessed systematically at four, six, and eight months of age. The Parkin KO rats did not have behavioral deficits at any of the ages tested. Motor functioning, including gait performance on the Rotarod, was intact.
The brains of Parkin KO rats are largely intact. A small, non-significant reduction in dopaminergic neurons was observed in the substantia nigra at eight months of age. There were no differences in striatal dopamine levels at four, six, or eight months compared to wild-type rats. There was no increase in α-synuclein protein in the striatum or any other brain region.
Levels of the protein tyrosine phosphatase STEP61 are elevated in the striatum of 12-month-old Parkin KO rats compared with wild-type controls. There was no such change in the cortex (Kurup et al., 2015).
The rat Park2 gene was disrupted using zinc finger nuclease (ZFN) technology. The targeted ZFN created a DNA strand break in exon 4 of Park2. Repair of this break created a deletion of five base pairs, leading to a frame shift and the creation of a premature stop codon.
When visualized, these models will distributed over a 18 month timeline demarcated at the following intervals: 1mo, 3mo, 6mo, 9mo, 12mo, 15mo, 18mo+.
- Neuronal Loss
- Dopamine Deficiency
- α-synuclein Inclusions
- Motor Impairment
- Mitochondrial Abnormalities
- Cognitive Dysfunction
There were no differences in striatal dopamine levels at 4, 6, or 8 months compared to wild-type rats.
There was no increase in α-synuclein protein in the striatum or any other brain region assessed.
A small, non-significant reduction in dopaminergic neurons was observed in the substantia nigra at eight months of age.
Parkin KO rats did not have behavioral deficits at any of the ages tested (4, 6, 8 months). Motor functioning, including gait performance on the Rotarod, was intact.
- Dave KD, De Silva S, Sheth NP, Ramboz S, Beck MJ, Quang C, Switzer RC 3rd, Ahmad SO, Sunkin SM, Walker D, Cui X, Fisher DA, McCoy AM, Gamber K, Ding X, Goldberg MS, Benkovic SA, Haupt M, Baptista MA, Fiske BK, Sherer TB, Frasier MA. Phenotypic characterization of recessive gene knockout rat models of Parkinson's disease. Neurobiol Dis. 2014 Oct;70:190-203. Epub 2014 Jun 24 PubMed.
- Kurup PK, Xu J, Videira RA, Ononenyi C, Baltazar G, Lombroso PJ, Nairn AC. STEP61 is a substrate of the E3 ligase parkin and is upregulated in Parkinson's disease. Proc Natl Acad Sci U S A. 2015 Jan 27;112(4):1202-7. Epub 2015 Jan 12 PubMed.
No Available Further Reading