Absence of nigral degeneration in aged parkin/DJ-1/PINK1 triple knockout mice - PubMed (original) (raw)

Absence of nigral degeneration in aged parkin/DJ-1/PINK1 triple knockout mice

Tohru Kitada et al. J Neurochem. 2009 Nov.

Abstract

Recessively inherited loss-of-function mutations in the parkin, DJ-1, or PINK1 gene are linked to familial cases of early-onset Parkinson's diseases (PD), and heterozygous mutations are associated with increased incidence of late-onset PD. We previously reported that single knockout mice lacking Parkin, DJ-1, or PINK1 exhibited no nigral degeneration, even though evoked dopamine release from nigrostriatal terminals was reduced and striatal synaptic plasticity was impaired. In this study, we tested whether inactivation of all three recessive PD genes, each of which was required for nigral neuron survival in the aging human brain, resulted in nigral degeneration during the lifespan of mice. Surprisingly, we found that triple knockout mice lacking Parkin, DJ-1, and PINK1 have normal morphology and numbers of dopaminergic and noradrenergic neurons in the substantia nigra and locus coeruleus, respectively, at the ages of 3, 16, and 24 months. Interestingly, levels of striatal dopamine in triple knockout mice were normal at 16 months of age but increased at 24 months. These results demonstrate that inactivation of all three recessive PD genes is insufficient to cause significant nigral degeneration within the lifespan of mice, suggesting that these genes may be protective rather than essential for the survival of dopaminergic neurons during the aging process. These findings also support the notion that mammalian Parkin and PINK1 may function in the same genetic pathway as in Drosophila.

PubMed Disclaimer

Figures

Fig. 1

Fig. 1

(a) The mouse parkin gene is located on chromosome 17, whereas the mouse DJ-1 and PINK1 genes are both on chromosome 4, with an allelic distance of 12.5 cM. (b, c) Western blot analysis confirms the absence of Parkin (b) and DJ-1 (c) in TKO brains. The same blots were incubated with an anti-α-tubulin antibody as loading controls. (d) Northern analysis using a probe specific for exon 8 shows the absence of PINK1 transcripts in TKO brains. The same blot was hybridized with a GAPDH cDNA probe as control. WT, wild-type; GAPDH, glyceraldehyde-3-phosphate dehydrogenase.

Fig. 2

Fig. 2

No neurodegeneration in the SNpc and LC of TKO mice. (a–d) Normal immunoreactivity and morphology of SN neurons in TKO mice at the age of 24 months. Scale bars: 100 μm. (e) Similar numbers of TH-immunoreactive neurons are present in the SNpc of TKO mice and wild-type controls at the ages of 3 months (+/+: 12720 ± 992, n = 4; −/−: 11080 ± 740, n = 4; p > 0.05), 16 months (+/+: 11460 ± 1735, n = 4; −/−: 11880 ± 605, n = 4; p > 0.05), and 24 months (+/+: 11008 ± 736, n = 5; −/−: 10440 ± 396, n = 4; p > 0.05). All data are expressed as mean ± SEM. (f–i) Normal immunoreactivity and morphology of TH+ neurons in the LC of TKO mice at the age of 24 months. Scale bars: 100 μm. (j) Similar numbers of TH-immunoreactive neurons are present in the LC of TKO mice and wild-type controls at the ages of 3 months (+/+: 308 ± 16, n = 3; −/−: 298 ± 13, n = 4; p > 0.05), 16 months (+/+: 284 ± 38, n = 3; −/−: 236 ± 17, n = 4; p > 0.05), and 24 months (+/+: 231 ± 21, n = 4; −/−: 265 ± 16, n = 4; p > 0.05). All data are expressed as mean ± SEM.

Fig. 3

Fig. 3

Increased DA in the striatum of TKO mice at 24 months of age. (a and b) Western analysis showed similar levels of TH in TKO mice at the ages of 16 months (+/+: 1.00 ± 0.11, n = 4; −/−: 1.07 ± 0.15, n = 4; p > 0.05) and 24 months (+/+: 1.00 ± 0.19, n = 5; −/−: 1.08 ± 0.12, n = 5; p > 0.05). Each value of the TH protein level is normalized to that of α-tubulin. (c) TH activity assay. DOPA content in the TKO striatum following NSD-1015 treatment at the age of 2–5 months (0.33 ± 0.04 ng/mg, n = 4) was unchanged compared with wild-type controls (0.30 ± 0.07 ng/mg, n = 4; p > 0.05). Each data point represents the mean ± SEM. (d) Levels of striatal DA content are similar in TKO mice and wild-type controls at the age of 16 months (+/+: 18.4 ± 2.0 ng/mg, n = 5; −/−: 18.5 ± 2.3 ng/mg, n = 5; p > 0.05) and increased in TKO mice at 24 months (+/+: 16.3 ± 1.8 ng/mg, n = 5; −/−: 24.6 ± 3.4 ng/mg, n = 4; *p < 0.05). (e) Levels of striatal HVA in TKO mice and wild-type controls at the ages of 16 months (+/+: 1.76 ± 0.28 ng/mg, _n_ = 5; −/−: 1.98 ± 0.18 ng/mg, _n_ = 5; _p_ > 0.05) and 24 months (+/+: 1.65 ± 0.23 ng/mg, n = 5; −/−: 2.67 ± 0.65 ng/mg, n = 4; p > 0.05). (f) Levels of striatal DOPAC in TKO mice and wild-type controls at the ages of 16 months (+/+: 1.53 ± 0.20 ng/mg, n = 5; −/−: 1.42 ± 0.18 ng/mg, n = 5; p > 0.05) and 24 months (+/+: 1.42 ± 0.13 ng/mg, n = 5; −/−: 2.09 ± 0.46 ng/mg, n = 4; p > 0.05). All data are expressed as mean ± SEM.

Similar articles

Cited by

References

    1. Albanese A, Valente EM, Romito LM, Bellacchio E, Elia AE, Dallapiccola B. The PINK1 phenotype can be indistinguishable from idiopathic Parkinson disease. Neurology. 2005;64:1958–1960. - PubMed
    1. Andres-Mateos E, Perier C, Zhang L, et al. DJ-1 gene deletion reveals that DJ-1 is an atypical peroxiredoxin-like peroxidase. Proc. Natl. Acad. Sci. USA. 2007;104:14807–14812. - PMC - PubMed
    1. Arrue A, Ruiz-Ortega JA, Ugedo L, Giralt MT. Short-term effects of 3,4-methylenedioximethamphetamine on noradrenergic activity in locus coeruleus and hippocampus of the rat. Neurosci. Lett. 2003;337:123–126. - PubMed
    1. Beal MF. Mitochondria, oxidative damage, and inflammation in Parkinson's disease. Ann. N Y Acad. Sci. 2003;991:120–131. - PubMed
    1. Bonifati V, Breedveld GJ, Squitieri F, et al. Localization of autosomal recessive early-onset parkinsonism to chromosome 1p36 (PARK7) in an independent dataset. Ann. Neurol. 2002;51:253–256. - PubMed

Publication types

MeSH terms

Substances

Grants and funding

LinkOut - more resources