Species: Rat
Genes: Park2
Modification: Park2: Knock-Out
Disease Relevance: Parkinson's Disease
Strain Name: HsdSage:LE-Park2^em1Sage; formerly LEH-Park2^TM1sage
Genetic Background: Long Evans Hooded
Availability: Available through Inotiv. Cryopreserved as heterozygous embryos. (Previously available through Envigo).

Summary

This knockout (KO) rat model was created at Sage Labs (acquired first by Horizon Discovery, then by Envigo, and most recently by Inotiv) in collaboration with the Michael J. Fox Foundation. It carries a disrupted Park2 (also known as Prkn) gene, which encodes the E3 ligase parkin. Park2 mRNA levels are decreased by about half in the brains of parkin KO rats and the protein is undetectable by western blot. Homozygous rats exhibit  minor behavioral alterations and have no significant degeneration of striatal neurons or loss of dopamine (Dave et al., 2014). However, changes in dopaminergic signaling have been detected at an early age (Gemechu et al., 2018), as were proteomic changes in mitochondria at striatal synapses and in nonsynaptic striatal samples (Stauch et al., 2016, Villeneuve et al., 2018).

Although they appear normal at birth, at 2 months of age, homozygous rats male KO rats exhibit a moderate reduction in stereotypic movements, such as scratching and grooming (Gemechu et al., 2018). A systematic analysis of their behavior at 4, 6, and 8 months of age, did not reveal any other behavioral deficits at any of the ages tested (Dave et al., 2014). Motor functioning, including gait performance on the Rotarod, was intact. Similarly, sensory responses, including orientation to an olfactory stimulus, were normal.

The brains of parkin KO rats are largely intact, although small compensatory changes in dopaminergic transmission occur early on. A non-significant reduction in dopaminergic neurons was observed in the substantia nigra at 8 months of age. There were no differences in striatal dopamine levels at 4, 6, or 8 months compared with wild-type rats. However, the activities of monoamine oxidases (MAOs), which break down dopamine, were reduced in the striata of 2-month-old male KO rats, and the levels of the MAO substrate β-phenylethylamine were increased compared with those of wild-type rats (Gemechu et al., 2018), In addition, levels of trace amine-associated receptor 1, which binds to β-phenylethylamine and regulates dopamine transmission, as well as postsynaptic dopamine D2 receptors, were reduced. Moreover, 2-month-old male KO rats had a weaker response to a low dose of methamphetamine, an indirect agonist of dopamine, than similarly treated wild-type rats (Gemechu et al., 2018). With regard to methamphetamine, parkin KO male rats (about 2 months of age) exhibited a greater place preference for a methamphetamine-paired environment in a place preference test and self-administered methamphetamine to a greater extent than wild-type rats, indicating that KO rats may serve as a model for methamphetamine use disorder (Sharma et al., 2021).

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).

Neurotransmitter release has been assessed by in vivo microdialysis in the striatum of parkin KO rats (Creed et al., 2019). Basal levels of neurotransmitters (dopamine, glutamate, acetylcholine) and dopamine metabolites (3,4-dihydroxyphenylacetic and homovanillic acid) did not differ from wild-type rats at 4, 8, and 12 months of age. However, basal levels of dopamine metabolites decreased with age in parkin KO rats, showing lower levels at 12 months of age than 8 months for both 3,4-dihydroxyphenylacetic and homovanillic acid. As for evoked release, glycine was released to a greater extent in parkin KO rats than wild-type rats following potassium stimulation at 12 months of age, but not at 4 or 8 months of age. Potassium-evoked glycine levels also became greater with age, where 12-month-old parkin KO rats exhibited greater release than 8- or 4-month-old KO rats.

Differences in mitochondrial protein expression also have been reported. Although oxygen consumption rates of striatal synaptic mitochondria of 23-month-old KO rats were similar to those of wild-type rats, trends towards a lower proton leak rate and an increased respiratory control ratio were observed. Moreover, proteomic analysis revealed differentially expressed mitochondrial proteins in the striatal synapses of 3-month-old KO rats compared with those of wild-type animals (Villeneuve et al., 2018). Mitochondrial function has also been examined by assessing the striatal nonsynaptic mitochondrial proteome and by a mitochondrial respiration assay in 3-month-old male parkin KO rats (Stauch et al., 2016). A total of 37 mitochondrial proteins were found to exhibit differential expression in nonsynaptic striatal samples from parkin KO rats compared with DJ-1 and PINK1 KO rats. However, similar to studies in synaptic samples, the oxygen-consumption rate did not differ in nonsynaptic striatal mitochondria of parkin KO rats versus wild-type rats.

There was no increase in α-synuclein protein in the striatum or any other brain region (Dave et al., 2014).

Modification Details

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.

Phenotype Characterization

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References

Paper Citations

1. 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.
2. Gemechu JM, Sharma A, Yu D, Xie Y, Merkel OM, Moszczynska A. Characterization of Dopaminergic System in the Striatum of Young Adult Park2-/- Knockout Rats. Sci Rep. 2018 Jan 24;8(1):1517. PubMed.
3. Stauch KL, Villeneuve LM, Purnell PR, Pandey S, Guda C, Fox HS. SWATH-MS proteome profiling data comparison of DJ-1, Parkin, and PINK1 knockout rat striatal mitochondria. Data Brief. 2016 Dec;9:589-593. Epub 2016 Sep 23 PubMed.
4. Villeneuve LM, Stauch KL, Purnell PS, Fox HS. Proteomic and functional data sets on synaptic mitochondria from rats with genetic ablation of Parkin. Data Brief. 2018 Oct;20:568-572. Epub 2018 Aug 28 PubMed.
5. Sharma A, Harutyunyan A, Schneider BL, Moszczynska A. Parkin regulates drug-taking behavior in rat model of methamphetamine use disorder. Transl Psychiatry. 2021 May 17;11(1):293. PubMed.
6. 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.
7. Creed RB, Menalled L, Casey B, Dave KD, Janssens HB, Veinbergs I, van der Hart M, Rassoulpour A, Goldberg MS. Basal and Evoked Neurotransmitter Levels in Parkin, DJ-1, PINK1 and LRRK2 Knockout Rat Striatum. Neuroscience. 2019 Jun 15;409:169-179. Epub 2019 Apr 25 PubMed.

External Citations

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Further Reading