Proteomic analysis of parkin knockout mice: alterations in energy metabolism, protein handling and synaptic function

Abstract

Parkin knockout (KO) mice show behavioural and biochemical changes that reproduce some of the presymptomatic aspects of Parkinson's disease, in the absence of neuronal degeneration. To provide insight into the pathogenic mechanisms underlying the preclinical stages of parkin-related parkinsonism, we searched for possible changes in the brain proteome of parkin KO mice by means of fluorescence two-dimensional difference gel electrophoresis and mass spectrometry. We identified 87 proteins that differed in abundance between wild-type and parkin KO mice by at least 45%. A high proportion of these proteins were related to energy metabolism. The levels of several proteins involved in detoxification, stress-related chaperones and components of the ubiquitin-proteasome pathway were also altered. These differences might reflect adaptive mechanisms aimed at compensating for the presence of reactive oxygen species and the accumulation of damaged proteins in parkin KO mice. Furthermore, the up-regulation of several members of the membrane-associated guanylate kinase family of synaptic scaffold proteins and several septins, including the Parkin substrate cell division control related protein 1 (CDCRel-1), may contribute to the abnormalities in neurotransmitter release previously observed in parkin KO mice. This study provides clues into possible compensatory mechanisms that protect dopaminergic neurones from death in parkin KO mice and may help us understand the preclinical deficits observed in parkinrelated parkinsonism. Keywords: knockout mice, parkin, proteomic, two-dimensional fluorescence difference gel electrophoresis. In 1998, the parkin gene was shown to be responsible for a distinct clinical and genetic entity in Japan, defined as autosomal recessive juvenile parkinsonism (Kitada et al. 1998). A series of parkin exon rearrangements and point mutations have since been identified in almost 50% of patients with familial autosomal recessive early-onset parkinsonism from different populations, and in 15% of non-familial cases (Lücking et al. 2000;Lohmann et al. 2003 Abbreviations used: AcCN, acetonitrile; CDCRel-1, cell division control related protein 1; 2D DIGE, two-dimensional difference gel electrophoresis; DTT, dithiothreitol; GTP2, glutathione S-transferase P2; IPG, immobilized pH gradient; KO, knockout; MAGUK, membraneassociated guanylate kinase; MALDI-TOF, matrix-assisted laser desorption/ionization-time of flight; MS, mass spectrometry; NSF, N-ethylmaleimide sensitive fusion protein; OTUB1, OTU-domain uba1-binding protein; PD, Parkinson's disease; PINK1, PTEN-induced kinase 1; UCH-L1, ubiquitin carboxyterminal hydrolase L1; WT, wild type.

The ubiquitin E3 ligase parkin regulates the proapoptotic function of Bax

“…On the other hand, mitochondrial depolarization may induce changes in parkin folding (i.e., unique access to the UBL domain, phosphorylation by PINK1) that promote its mitochondrial translocation and facilitate the observed docking of the proteasome adjacent to parkin-decorated mitochondria during mitophagy (28). The hypothesis that a specific conformation or pool of Bax is recognized by parkin is supported by the observation that the cytosolic levels of Bax were not robustly affected by parkin expression and that proteomic screens of whole tissue failed to identify changes in Bax levels in parkin KO brain (29,30). Conversely, it may also indicate that not all of the parkin-ubiquitinated Bax is destined for degradation, as some studies suggest that parkin can facilitate K63 ubiquitin linkages (31), which may alter protein trafficking and not induce degradation.…”

Parkin-mediated Monoubiquitination of the PDZ Protein PICK1 Regulates the Activity of Acid-sensing Ion Channels

“…The ensuing accumulation of parkin substrates is believed, in turn, to induce the cellular toxicity and dopamine neuron loss seen in PD. Although numerous parkin substrates have been identified (Zhang et al, 2000;Chung et al, 2001;Imai et al, 2001;Corti et al, 2003;Staropoli et al, 2003), there is still controversy as to which of these accumulate in the brains of parkin knockout (KO) mice (Goldberg et al, 2003;Itier et al, 2003;Von Coelln et al, 2004;Ko et al, 2005;Perez and Palmiter, 2005;Periquet et al, 2005) and as to their respective roles in the pathogenesis of PD (Cookson, 2005;Moore et al, 2005).…”

“…The ensuing accumulation of parkin substrates is believed, in turn, to induce the cellular toxicity and dopamine neuron loss seen in PD. Although numerous parkin substrates have been identified (Zhang et al, 2000;Chung et al, 2001;Imai et al, 2001;Corti et al, 2003;Staropoli et al, 2003), there is still controversy as to which of these accumulate in the brains of parkin knockout (KO) mice (Goldberg et al, 2003;Itier et al, 2003;Von Coelln et al, 2004;Ko et al, 2005;Perez and Palmiter, 2005;Periquet et al, 2005) and as to their respective roles in the pathogenesis of PD (Cookson, 2005;Moore et al, 2005).In addition to its traditional role, Ub can serve as a reversible posttranslational modification that regulates the function of tagged proteins without necessarily leading to their destruction by the proteasome (Hicke and Dunn, 2003;Mukhopadhyay and Riezman, 2007). Depending on the length and architecture of the Ub chain, ubiquitination has been implicated in a variety of cellular functions as diverse as signal transduction, transcription, and membrane trafficking (Mukhopadhyay and Riezman, 2007).…”

Modèles animaux des maladies neuro-dégénératives

“…Les souris invalidées pour le gène de la parkine n'ont pas de phénotype clinique, mais des perturbations de l'expression de protéines impliquées dans le métabolisme énergétique, le fonctionnement synaptique et la voie de dégradation ubiquitine-protéasome [44]. Plusieurs souris invalidées pour le gène de la frataxine ont été produites par une technique de ciblage génique conditionnel.…”