Homozygous PINK1 C-terminus mutation causing early-onset parkinsonism.
ABSTRACT Two homozygous mutations in the PINK1 gene, encoding a mitochondrial putative protein kinase, recently have been identified in families with PARK6-linked, autosomal recessive early-onset parkinsonism (AREP). Here, we describe a novel homozygous mutation (1573_1574 insTTAG) identified in an AREP patient, which causes a frameshift and truncation at the C-terminus of the PINK1 protein, outside the kinase catalytic domain. The clinical phenotype includes early-onset (28 years) parkinsonism, foot dystonia at onset, good levodopa response, slow progression, early levodopa-induced dyskinesias, and sleep benefit, thereby resembling closely parkin-related disease. These findings confirm that recessive mutations in PINK1 cause early-onset parkinsonism and expand the associated clinical phenotype.
SourceAvailable from: Matthew Betts[Show abstract] [Hide abstract]
ABSTRACT: Parkinson’s disease (PD) is characterised by a progressive loss of dopaminergic neurones from the SNpc, leading to numerous downstream changes in the basal ganglia circuitry. Overactivity of the glutamatergic subthalamonigral pathway may underlie this continual degeneration of the nigrostriatal system. With this in mind, this thesis examined whether selective activation of group III metabotropic glutamate receptor subtypes may offer a novel strategy to halt persistent degeneration in PD. Initial distribution studies revealed mGlu4 and 7 group III mGlu receptor subtypes, demonstrated particularly intense immunoreactivity in the SNpc, suggesting these receptors may be ideally positioned to provide neuroprotective effects. Therefore, the first objective was to confirm this neuroprotective possibility using a broad spectrum agonist, L-AP4. Sub-chronic supranigral L-AP4 treatment mediated functional neuroprotection against a unilateral 6-OHDA lesion of the SN, confirmed by behavioural assessment and post-mortem analyses. Secondly, the pharmacological identity of the group III mGlu receptor mediating this protective effect was examined. To investigate mGlu4 receptors, the novel mGlu4 selective PAM VU0155041, was also shown to provide functional neuroprotection in the 6-OHDA rat model to an almost comparable level reached with L-AP4. Whilst these neuroprotective effects are likely mediated by an inhibition of glutamate to protect from glutamate-mediated excitotoxicity, VU015504 also led to a significant reduction in levels of GFAP and IBA-1 suggesting an additional anti-inflammatory action. Further studies revealed little evidence for co-localisation of mGlu4 receptors with GFAP in the SN suggesting this anti-inflammatory component likely reflects an indirect effect via stimulation of neuronal mGlu4 receptors. Finally, to investigate mGlu7 receptors, the selective allosteric agonist AMN082, was also shown to protect the nigrostriatal tract and demonstrate a degree of preservation of motor function. In contrast, mGlu8 receptor activation using the selective agonist DCPG, failed to protect the nigrostriatal tract or preserve motor behaviour. Collectively, these findings demonstrate that, of the group III mGlu receptors investigated, mGlu4 offers the most potential as a promising target for establishing disease modification in PD.
[Show abstract] [Hide abstract]
ABSTRACT: Parkinson's disease (PD) is the second most common neurodegenerative disorder that is characterized by two major neuropathological hallmarks: the degeneration of dopaminergic neurons in the substantia nigra (SN) and the presence of Lewy bodies in the surviving SN neurons, as well as other regions of the central and peripheral nervous system. Animal models have been invaluable tools for investigating the underlying mechanisms of the pathogenesis of PD and testing new potential symptomatic, neuroprotective and neurorestorative therapies. However, the usefulness of these models is dependent on how precisely they replicate the features of clinical PD with some studies now employing combined gene-environment models to replicate more of the affected pathways. The rotenone model of PD has become of great interest following the seminal paper by the Greenamyre group in 2000 (Betarbet et al., 2000). This paper reported for the first time that systemic rotenone was able to reproduce the two pathological hallmarks of PD as well as certain parkinsonian motor deficits. Since 2000, many research groups have actively used the rotenone model worldwide. This paper will review rotenone models, focusing upon their ability to reproduce the two pathological hallmarks of PD, motor deficits, extranigral pathology and non-motor symptoms. We will also summarize the recent advances in neuroprotective therapies, focusing on those that investigated non-motor symptoms and review rotenone models used in combination with PD genetic models to investigate gene-environment interactions.NeuroToxicology 12/2014; 46:101-116. DOI:10.1016/j.neuro.2014.12.002
10/2006, Degree: Doctoral degree in genetic epidemiology, Supervisor: Professor CM van Duijn